Airody Vasudeva Adhikari

Verified email at gmail.com

Professor, Yenepoya Research Centre, Yenepoya University
Yenepoya deemed to be University



                               

http://researchid.co/vasudevaadhikari

Dr. A. Vasudeva Adhikari, at present, is working as Professor at Yenepoya Research Centre, Yenepoya deemed to be University, Mangalore. Earlier to this, he was serving as Professor - HAG in the Chemistry Department of National Institute of Technology Karnataka, Surathakal, from 1989, with 12 years of previous teaching experience at various institutes. He earned his masters (1976) from Mysore University) and a doctorate degree (1987) from Karnatak University, Dharwad, and he started carrying out his independent research from 1989 at NITK. He has made significant research contributions to Organic Chemistry/Material Science, seeking to utilize the newly synthesized organic small/macromolecules for different applications like Organic Electronics, Medicinal Fields, and Nonlinear Optics. He has published more than 140 peer-reviewed journal articles with about 3000 citations (h-index 31, and i10: 72) and more than 80 paper-presentations at various national and international conferences held in India and abroad. To his credit, he has one book chapter, six research projects, and memberships in many chemistry-related associations. He has successfully guided more than 20 Ph.D.s, 25 M.Sc., several B.Tech./M.Tech. projects during his 31 years of service at NITK. He has good experience in industry-institute interactions and consultancy activities gaining social, economic, and academic benefits.

EDUCATION

M.Sc. (Organic Chemistry, Mysore University), Ph.D. (Organic Chemistry Karnatak University)

RESEARCH INTERESTS

Synthetic Organic Chemistry: Molecular design of new organic molecules; Developing synthetic routes; Synthesis of new molecular entities with possible applications in Medicinal, Organic Electronics, and NLO fields; Retrosynthesis, Conducting polymers, Nanochemistry, Natural Products, Biofuels and Computational Studies (Broad Area: Chemical Biology)

FUTURE PROJECTS

Molecular design and synthesis of new indole-based hybrid molecules as potential anti-cancer agents

New indole-based hybrid heterocyclic scaffolds will be identified as anticancer agents based on Schrodinger’s software. These molecules with varied structural modifications will be synthesized, well-characterized, and evaluated for in vivo and in vitro anticancer properties to establish structure-property relationships. Thus, the lead molecule will be identified.


Applications Invited

Synthesis of new poly(pyrrole)-based nanocomposites for biosensing applications

New poly(pyrrole)s will be synthesized electrochemically and their nano-composites will be prepared and characterized. Their bio-sensing applications will be investigated and new devices will be fabricated as an analyzing tool.


Applications Invited

Applications of NMR Spectroscopy as an Important Tool for Metabolomics Research

NMR-based studies on metabolites in combination with LCMS tool: Characterization of various metabolites in biosamples.


Applications Invited
131

Scopus Publications

Scopus Publications

  • Synthesis, characterization and electroluminescence studies of cyanopyridine-based π-conjugative polymers carrying benzo[: C] [1,2,5]thiadiazole and naphtho[1,2- c:5,6- c ′]bis([1,2,5]thiadiazole) units
    Naveenchandra Pilicode, Praveen Naik, Madhukara Acharya, and Airody Vasudeva Adhikari

    New Journal of Chemistry, ISSN: 11440546, eISSN: 13699261, Pages: 10796-10805, Published: 14 July 2020 Royal Society of Chemistry (RSC)
    Four new cyanopyridine based polymers, i.e.TDPy1-4 were designed, synthesized and well-characterized. The detailed studies reveal that the polymers own all the prerequisites required for the PLED application as active green light emitters.

  • Solvent selection for highly reproducible carbon-based mixed-cation hybrid lead halide perovskite solar cells via adduct approach
    Kavya S. Keremane, Sateesh Prathapani, Lew Jia Haur, Damodaran Bahulayan, Airody Vasudeva Adhikari, Anish Priyadarshi, and Subodh G. Mhaisalkar

    Solar Energy, ISSN: 0038092X, Volume: 199, Pages: 761-771, Published: 15 March 2020 Elsevier BV
    Abstract The major problem identified in carbon-based mixed cation perovskite solar cells (PSCs) is the selection of a suitable solvent for single-step solution-processed perovskite deposition in order to promote their scalable production. Herein we report a detailed study on the selection of appropriate solvent for the one-step deposition of cesium-formamidinium lead iodide (Cs0.1FA0.9PbI3) perovskite via Lewis acid-base adduct approach for fully printable mesoporous PSCs with mesoporous TiO2/ZrO2/C architecture. Highly reproducible Cs0.1FA0.9PbI3 solar cells were fabricated via adducts of PbI2 with eco-friendly dimethyl sulfoxide (DMSO). The best cells fabricated with the above approach yielded a photoconversion efficiency (PCE) of 12.33% for a small area device (active area: 0.09 cm2) and 10.1% for a large area device (active area 0.7cm2). The average power conversion efficiency for 62 PSCs was found to be 10.5% under an AM 1.5G illumination. Finally, the mixed cation perovskite in carbon architecture using the Lewis acid-base adduct approach is remarkably stable, with less than 1% change from the initial PCE after 1800h of storage under dark ambient conditions (25 °C, 60–70% RH).

  • New cyanopyridine based conjugated polymers carrying auxiliary electron donors: From molecular design to blue emissive PLEDs
    Naveenchandra Pilicode, Praveen Naik, K.M. Nimith, Madhukara Acharya, M.N. Satyanarayan, and Airody Vasudeva Adhikari

    Dyes and Pigments, ISSN: 01437208, eISSN: 18733743, Volume: 174, Published: March 2020 Elsevier BV
    Abstract Three new D-A (Donor-Acceptor) configured conjugated polymers, i.e. PPy1-3, centered on strong electron accepting cyanopyridine scaffold carrying varied auxiliary donors, viz. phenylene (PPy1), biphenyl (PPy2), and fluorene (PPy3) were designed and synthesized as blue emitters for PLEDs. The new polymers were subjected to spectral, thermal, photophysical and electrochemical characterization. Also, computational studies (DFT) were performed on the repeating units of polymer using Turbomole 7.2 V software package at the B3LYP/TZVP hybrid levels. Further, their weight average molecular masses were found to be 38.8 kDa, 38.9 kDa and 57.7 kDa, respectively as determined by GPC technique. Furthermore, the new polymers PPy1-3, were shown to be stable thermally up to 308–374 °C. Evidently, they exhibited good photophysical behavior with their optical energy band gaps of 2.53–2.64 eV. Finally, the polymers PPy1-3 were employed as an active emissive layer in standard ITO/PEDOT:PSS/Polymer/Al configured PLEDs. Interestingly, at 12 V all the newly fabricated devices exhibit a stable blue characteristic electroluminescence with low threshold voltages of 3.40–5.20 V, confirming an efficient injection of electrons in the diodes. From the results, it is clear that, the polymers PPy1-3, can be considered as prospective blue light emitters for PLED application.

  • Nicotinonitrile centered luminescent polymeric materials: Structural, optical, electrochemical, and theoretical investigations
    Naveenchandra Pilicode, Praveen Naik, and Airody Vasudeva Adhikari

    Polymer Engineering and Science, ISSN: 00323888, eISSN: 15482634, Published: 2020 Wiley

  • Simple thiophene based organic dyes as active photosensitizers for dssc application: From molecular design to structure property relationship
    Kavya S. Keremane, , Praveen Naik, Airody Vasudeva Adhikari, , and

    Journal of Nano- and Electronic Physics, ISSN: 20776772, eISSN: 23064277, Published: 2020 Sumy State University

  • New cyanopyridine-based π-conjugative poly(azomethine)s: Synthesis, characterization and electroluminescence studies
    Naveenchandra Pilicode, Praveen Naik, K. M. Nimith, Madhukara Acharya, M. N. Satyanarayan, and Airody Vasudeva Adhikari

    Polymers for Advanced Technologies, ISSN: 10427147, eISSN: 10991581, Published: 2020 Wiley

  • Asymmetric Dual Anchoring Sensitizers/Cosensitizers for Dye Sensitized Solar Cell Application: An Insight into Various Fundamental Processes inside the Cell
    Rajalakshmi Kesavan, Fathy Attia, Rui Su, P. Anees, Ahmed El-Shafei, and Airody Vasudeva Adhikari

    Journal of Physical Chemistry C, ISSN: 19327447, eISSN: 19327455, Volume: 123, Pages: 24383-24395, Published: 10 October 2019 American Chemical Society (ACS)
    To study the various fundamental processes occurring inside the dye sensitized solar cell (DSSC), we have fabricated devices employing newly synthesized diphenylamine-based organic dyes with A-D-π-A configuration, carrying four different anchoring groups, namely, cyanoacetic acid (DDC), rhodanine acetic acid (DDR), 4-hydrazinylbenzoic acid (DDH), and barbituric acid (DDB), as effective sensitizers/cosensitizers. In the present work, all the bianchoring dyes were subjected to photophysical, electrochemical, thermodynamic, photoelectrochemical, and theoretical studies. All of them displayed characteristic λabs and λemi in the range of 415–480 and 570–680 nm, respectively. Their optical and electrochemical band gaps were calculated to be in the order of 2.1 to 2.3 eV. The calculated driving forces for electron injection (ΔGinj), recombination (ΔGinj), and regeneration (ΔGreg) processes were found to be negative, showing the feasibility of these processes, while their DFT studies clearly indicated the directi...

  • Self-assembly of taper- and wedge-shaped maleimide derivatives: Synthesis and structure-property relationship
    D.R. Vinayakumara, Sandeep Kumar, S. Krishna Prasad, and Airody Vasudeva Adhikari

    Journal of Molecular Liquids, ISSN: 01677322, Volume: 284, Pages: 765-772, Published: 15 June 2019 Elsevier BV
    Abstract Herein, we describe design and synthesis of five new amphiphilic systems, viz. 10b-c and 11a-c composed of maleimide at the focal point and alkoxy phenyl ring at the periphery. Their self-assembling behaviour was examined systematically by varying the length of hydrophobic part and aromatic core segment. Evidently, on increasing the aromatic core length, maleimide based amphiphiles relatively emerge as two distinct molecular structures, i.e. wedge- and tapered-shaped. The mesomorphic studies of the two series reveal that, tapered-shaped maleimide derivatives assemble into a smectic A phase with an interesting phasmidic arrangement, whereas the wedge-shaped molecules exclusively form a prospective supramolecular hexagonal columnar mesophase through the intermolecular hydrogen-bonding via maleimide head group. These self-assembled materials could demonstrate high-sensitivity towards various external stimuli.

  • New blue light emitting cyanopyridine based conjugated polymers: From molecular engineering to PLED applications
    Naveenchandra Pilicode, Nimith K. M, Madhukara Acharya, Praveen Naik, Satyanarayan M. N, and Airody Vasudeva Adhikari

    Journal of Photochemistry and Photobiology A: Chemistry, ISSN: 10106030, Volume: 378, Pages: 38-45, Published: 1 June 2019 Elsevier BV
    Abstract In this work, we report the design of three new cyanopyridine scaffold based polymers, viz. TPy1-3 as potential blue light emitters for PLED applications. The new polymer design comprise, a cyanopyridine core as an electron accepting entity, thiophene as an electron donating unit with different auxiliary donors, viz. phenylene (TPy1), biphenyl (TPy2), and fluorene (TPy3), and have been synthesized, following standard synthetic protocols including Suzuki-cross coupling polymerization reaction. Further, in order to assess all the prerequisites to act as an active emitter, the polymers TPy1-3, were subjected to structural, thermal, linear optical, electrochemical and computational studies. The results revealed that, all the polymers were thermally stable up to 300 ⁰C and their estimated optical band-gaps were found to be 2.59–2.80 eV. Finally, new polymer light emitting diode (PLED) were fabricated by employing the polymers TPy1-3, as active emissive material with a configuration of ITO/PEDOT: PSS/Polymer/Al. Interestingly, all the fabricated devices, exhibited an intense blue electroluminescence at 12 V with low threshold voltages of 4.2–4.8 V, signifying an effective injection of electron in the device.

  • Reduction of nitro compounds carrying electron withdrawing groups: A convenient approach without metal catalyst
    K.A. Vishnumurthy and A.V. Adhikari

    Chemical Data Collections, eISSN: 24058300, Published: April 2019 Elsevier BV
    Abstract In this communication we report a convenient reduction technique for conversion of electron deficient aromatic nitro compounds to corresponding amino derivatives using hydrazine hydrate without any metal catalyst. The reduction process is carried out in different solvents under heating condition and microwave irradiation. In this method three novel substituted amines were synthesized from their respective nitro compounds with quantitative yield. Interestingly, the reduction process went smoothly without formation of any side product. The reaction is highly selective to nitro compounds without affecting ester functionality. Further it has been observed that the nature of substituent attached to nitro compound has a major role in reduction rate. As electron withdrawing nature increases the reduction takes place faster. Also it has been observed that the reaction is even faster in microwave irradiation without using of any organic solvent. The probable mechanism of reduction of nitro compound has been highlighted.

  • Highly fluorescent materials derived from ortho-vanillin: Structural, photophysical electrochemical and theoretical studies
    Sachin Poojary, Madhukara Acharya, Abdul Ajees Abdul Salam, Dhananjaya Kekuda, Upendra Nayek, S. Madan Kumar, Airody Vasudeva Adhikari, and Dhanya Sunil

    Journal of Molecular Liquids, ISSN: 01677322, Volume: 275, Pages: 792-806, Published: 1 February 2019 Elsevier BV
    Abstract Small-molecule organic fluorophores are highly in demand attributed to their extensive prospective in material and biomedical applications. Particularly, luminescent π-conjugated organic molecules that possess an efficient solid-state emission are excellent candidates for optoelectronic devices. Focusing on high demand of organic fluorophores, we herein report the synthesis of three organic fluorescent materials derived from o‑vanillin, viz. an ester (F1), an azine (F2) and an azo dye (F3). Interestingly, F2 exhibited very intense luminescence in its aggregate phase due to the restriction in intra-molecular rotation (RIR), as demonstrated by solution thickening studies. Further, its Single Crystal X-ray Crystallography (SCXRD) study suggested the existence of various intra and inter molecular interactions and gave evidences for locked intra-molecular rotations of the benzene rings in the rigid conformation of the molecule. The bathochromic shift in fluorescence from solution to solid phase was confirmed by its thin-film emission spectrum, which evidences the formation of J-aggregates. The observed RIR, development of J-aggregates and high conjugation in F2 impart an excellent fluorescence in its aggregated state. Thin films of both F2 and F3 on ITO plates exhibited a bathochromic shift with a deep orange to red photoluminescence on UV excitation. Furthermore, the morphological characterization revealed the presence of clear dense grains in case of F2 and F3, while the DSC analysis indicated phase transitions of all the derivatives. As seen from dielectric measurement studies, the azo dye F3 exhibited the highest dielectric constant among the three derivatives. The electronic and photophysical data based on Density Functional Theory (DFT) and Time Dependent-DFT (TD-DFT) calculations are in agreement with the experimental results. All the above data clearly advocate that, the synthesized fluorophoric o‑vanillin derivatives are excellent candidates for electro-optical devices.

  • Supramolecular columnar self-assembly of wedge-shaped rhodanine based dyes: Synthesis and optoelectronic properties
    D.R. Vinayakumara, Sandeep Kumar, and Airody Vasudeva Adhikari

    Journal of Molecular Liquids, ISSN: 01677322, Volume: 274, Pages: 215-222, Published: 15 January 2019 Elsevier BV
    Abstract The development of small π-conjugated functional organic molecules capable of forming supramolecular columnar self-assembly, is a rapidly growing area of material research. In this context, the present work describes the design and synthesis of a new series of wedge-shaped rhodanine derivatives with D-A configuration, viz. RA1–RA5. Their LC properties were studied by employing DSC, POM and XRD techniques. The mesophase behavior was investigated as a function of chain length, density and position of alkoxy terminals to understand structure-property relationship. Interestingly, the longer chain analog, i.e. RA3 demonstrated H-bonded disc-like macrocyclic structures, causing an imperative columnar hexagonal phase at ambient temperature. Further, their photophysical and electrochemical properties were evaluated. They showed a good dye property attributing to effective intramolecular interactions, as confirmed by experimental and theoretical studies. Conclusively, RA3 has been considered to be a potential candidate for its application in organic electronics.

  • New cyanopyridone-based unsymmetrical dyads: The effect of donor strength on their optoelectronic properties
    D. R. Vinayakumara, Rajalakshmi Kesavan, Sandeep Kumar, and Airody Vasudeva Adhikari

    Photochemical and Photobiological Sciences, ISSN: 1474905X, eISSN: 14749092, Pages: 2052-2060, Published: 2019 Royal Society of Chemistry (RSC)
    Here, we deliberated the effect of donor strength on the electro-optical properties of D–A–D′ configured new cyanopyridone dyads by means of detailed experimental and theoretical studies.

  • Columnar self-assembly of novel benzylidenehydrazones and their difluoroboron complexes: Structure-property correlations
    D. R. Vinayakumara, K. Swamynathan, Sandeep Kumar, and Airody Vasudeva Adhikari

    New Journal of Chemistry, ISSN: 11440546, eISSN: 13699261, Pages: 7099-7108, Published: 2019 Royal Society of Chemistry (RSC)
    A series of prospective columnar liquid crystalline materials derived from novel organoboron complexes has been developed by virtue of their application in organic electronic devices.

  • Simple diphenylamine based D-π-A type sensitizers/co-sensitizers for DSSCs: A comprehensive study on the impact of anchoring groups
    Rajalakshmi Kesavan, Islam M. Abdellah, Surya Prakash Singh, Ahmed El-Shafei, and Airody Vasudeva Adhikari

    Physical Chemistry Chemical Physics, ISSN: 14639076, Pages: 10603-10613, Published: 2019 Royal Society of Chemistry (RSC)
    Three new diphenylamine based metal-free dyes were designed and developed as efficient sensitizers as well as co-sensitizers along with N3 in DSSCs. Their detailed photophysical, electrochemical, theoretical and photovoltaic properties have been explored.

  • New fluorescent columnar mesogens derived from phenanthrene-cyanopyridone hybrids for OLED applications
    D. R. Vinayakumara, Hidayath Ulla, Sandeep Kumar, M. N. Satyanarayan, and Airody Vasudeva Adhikari

    Materials Chemistry Frontiers, eISSN: 20521537, Pages: 2297-2306, Published: December 2018 Royal Society of Chemistry (RSC)
    We report the design, synthesis, and self-assembly of a novel series of pseudodiscoid dyads comprising electron-rich dialkoxyphenanthrene and trialkoxyphenyl rings appended to an electron-deficient cyanopyridone core.

  • An Efficient Aniline-Based Co-Sensitizer for High Performance N3-Sensitized Solar Cells
    Praveen Naik, Islam M. Abdellah, M. Abdel‐Shakour, Madhukara Acharaya, Naveenchandra Pilicode, Ahmed El‐Shafei, and Airody Vasudeva Adhikari

    ChemistrySelect, eISSN: 23656549, Pages: 12297-12302, Published: 23 November 2018 Wiley

  • Improvement in performance of N3 sensitized DSSCs with structurally simple aniline based organic co-sensitizers
    Praveen Naik, Islam M. Abdellah, M. Abdel-Shakour, Rui Su, Kavya S. Keremane, Ahmed El-Shafei, and Airody Vasudeva Adhikari

    Solar Energy, ISSN: 0038092X, Volume: 174, Pages: 999-1007, Published: 1 November 2018 Elsevier BV
    Abstract In this work, we report comprehensive photovoltaic investigation of four structurally simple D-A configured organic dyes, A1-4 as active co-sensitizers in DSSCs sensitized with well-known Ru (II) based N3 dye. These effective co-sensitizers (A1-4) comprise N,N-dimethylaniline ring as donor scaffold linked with electron withdrawing functionalities, viz. barbituric acid (A1), N,N-dimethyl barbituric acid (A2), thiobarbituric acid (A3), and N,N-diethyl thiobarbituric acid (A4) as acceptor/anchoring units. In the present study, for the first time we have demonstrated the profound role of various simple organic molecules carrying different heterocyclic anchoring units on the photovoltaic parameters of the N3 sensitized devices. Also, the effect of concentration of sensitizer/co-sensitizers on the device performance characteristics has been investigated in depth. From the results, it is evident that, the device fabricated using co-sensitizer A2 carrying N,N-dimethyl barbituric acid along with sensitizer N3 in all concentrations outperformed when compared to N3 alone or other co-sensitizers. Interestingly, the best photovoltaic performance was obtained for the co-sensitized device fabricated using 0.3 mM co-sensitizer A2 along with 0.2 mM of N3 sensitizer. It displayed PCE of 7.02% with JSC of 15.27 mA·cm−2, VOC of 0.671 V and FF of 68.47%. Thus, the observed results have thrown new light upon the device optimization to yield DSSCs with improved performance by the selection of matchable co-sensitizers at appropriate concentrations.

  • New cyanopyridine based conjugative polymers as blue emitters: Synthesis, photophysical, theoretical and electroluminescence studies
    Naveenchandra Pilicode, Nimith K M, Satyanarayan M N, and Airody Vasudeva Adhikari

    Journal of Photochemistry and Photobiology A: Chemistry, ISSN: 10106030, Volume: 364, Pages: 6-15, Published: 1 September 2018 Elsevier BV
    Abstract Herein, we report the design of three new blue light emitting conjugated polymers (Th-Py-1, Th-Py-2 and Th-Py-3), carrying cyanopyridine ring as a strong electron accepting unit and thiophene as well as phenylene vinylene scaffolds with different substituents, as electron donating moieties. The newly designed monomers/polymers were synthesized using well-known synthetic protocols such as cyclocondensation, O-alkylation, Suzuki cross coupling, Wittig and Knoevenagel reactions. They were well-characterized by spectral, thermal, photophysical, electrochemical and gel permeation chromatography (GPC) techniques. Further, they were subjected to theoretical studies using DFT simulations, performed at B3LYP/TZVP level using Turbomole 7.2 V software package. The new polymers were tested in PLED devices (ITO/PEDOT: PSS/Polymer/Al) as emissive materials. Optical studies revealed that, all the polymers displayed light absorption in the range of 377–397 nm and blue light emission in the order of 432–482 nm, respectively. Further, their band-gaps were calculated to be in the order of 2.55–2.64 eV using both optical and electrochemical data. Furthermore, the TGA study indicated that, they possess good thermal stability with onset decomposition temperature, greater than 300 ⁰C under nitrogen atmosphere. Interestingly, use of these polymers in new PLEDs as emissive layers, has shown improved performance when compared to previously reported polymers in similar type of devices. They show blue light emission with a low threshold voltage of 3.5–3.9 V, affirming an efficient electron injection in the diodes.

  • Highly efficient carbazole based co-sensitizers carrying electron deficient barbituric acid for NCSU-10 sensitized DSSCs
    Praveen Naik, Kavya S. Keremane, Mohamed R. Elmorsy, Rui Su, Ahmed El-Shafei, and Airody Vasudeva Adhikari

    Solar Energy, ISSN: 0038092X, Volume: 169, Pages: 386-391, Published: 15 July 2018 Elsevier BV
    Abstract Herein, we report a comparative study of four interesting metal-free carbazole based organic dyes with different structural configurations, carrying electron deficient barbituric acid (C1-4), as effective co-sensitizers in DSSCs sensitized with NCSU-10 dye. The new entities comprise different structural architectures, viz. D-A (C1), D-π-A (C2), D-D-π-A (C3) and D-A-π-A (C4) configurations with same accepting/anchoring moiety. They consist of carbazole as donor scaffold linked to barbituric acid as an acceptor/anchoring unit via different π-spacers. This paper describes the study of all the four co-sensitizers with regard to their structural, photophysical, electrochemical, theoretical and photovoltaic investigations. Also, it includes their structure-performance correlation study in detail. The devices co-sensitized with C1-4 displayed the superior photovoltaic performance when compared to NCSU-10 alone. The results ameliorate the role of efficient co-sensitizers to yield DSSC with improved performance.

  • New carbazole based dyes as effective co-sensitizers for DSSCs sensitized with ruthenium (II) complex (NCSU-10)
    Praveen Naik, Rui Su, Mohamed R. Elmorsy, Ahmed El-Shafei, and Airody Vasudeva Adhikari

    Journal of Energy Chemistry, ISSN: 20954956, Pages: 351-360, Published: 1 March 2018 Elsevier BV
    Abstract Herein, we report the design and synthesis of three new D–A type metal-free carbazole based dyes ( S 1–3 ) as effective co-sensitizers for dye-sensitized solar cell (DSSC) sensitized with Ru(II) complex ( NCSU-10 ). In this new design, the electron rich carbazole unit was attached to three different electron withdrawing/anchoring species, viz. 4-amino benzoic acid, sulfanilic acid and barbituric acid. The dyes were characterized by spectral, photophysical and electrochemical analysis. Their optical and electrochemical parameters along with molecular geometries, optimized from DFT have been employed to apprehend the effect of the structures of these co-sensitizers on the photovoltaic performances. Further, S 1–3 dyes were co-sensitized along with a well-known NCSU-10 dye in order to broaden the spectral response of the co-sensitized devices and hence improve the efficiency. The photovoltaic performance studies indicated that, the device fabricated using S 1 dye as co-sensitizer with 0.2 mM of NCSU-10 exhibited improved PCE of 9.55% with J SC of 22.85 mA cm −2 , V OC of 0.672 V and FF of 62.2%, whereas the DSSC fabricated with dye NCSU-10 (0.2 mM) alone displayed PCE of 8.25% with J SC of 20.41 mA cm −2 , V OC of 0.667 V and FF of 60.6%. Furthermore, electronic excitations simulated using time-dependent DFT, were in good agreement with the experimentally obtained results of the co-sensitizers, indicating that the exchange-correlation function and basis set utilized for predicting the spectra of the co-sensitizers are quite appropriate for the calculations. In conclusion, the results showed the potential of simple organic co-sensitizers in the development of efficient DSSCs.

  • Investigation of new carbazole based metal-free dyes as active photo-sensitizers/co-sensitizers for DSSCs
    Praveen Naik, Rui Su, Mohamed R. Elmorsy, Ahmed El-Shafei, and Airody Vasudeva Adhikari

    Dyes and Pigments, ISSN: 01437208, eISSN: 18733743, Volume: 149, Pages: 177-187, Published: February 2018 Elsevier BV
    Abstract Herein, we report the molecular design, synthesis and characterization of three new D-D-π-A configured metal-free chromophores D 1-3 for their application in DSSCs as sensitizers as well as co-sensitizers. The new entities comprise carbazole as donor scaffold, 4-methoxyphenyl group as auxiliary donor and three different units, viz. cyanoacetic acid, 2, 4-thiazolidinedione and barbituric acid as acceptor/anchoring groups. Their photochemical, electrochemical and theoretical studies were carried out in order to assess their feasibility as active sensitizers. Further, D 1-3 were exploited as co-sensitizers along with NCSU-10 dye. Their photoelectrochemical performances and charge transport properties in fabricated DSSCs were studied. The results revealed that D 1 sensitizer displayed the highest PCE of 2.20% among the three dyes. D 3 when co-sensitized with NCSU-10 displayed an improved PCE of 8.32% ( J SC  = 19.25 mA.cm −2 , V OC  = 0.680 V, FF  = 63.7%) while NCSU-10 alone exhibited PCE of 8.25% ( J SC  = 20.41 mA.cm −2 , V OC  = 0.667 V, FF  = 60.6%).

  • Molecular Engineering of a New Organic Chromophore with D-π-A Architecture for Dye-Sensitized Solar Cells
    Materials Today: Proceedings, eISSN: 22147853, Pages: 21498-21504, Published: 2018

  • Optoelectronic exploration of novel non-symmetrical star-shaped discotic liquid crystals based on cyanopyridine
    D. R. Vinayakumara, K. Swamynathan, Sandeep Kumar, and Airody Vasudeva Adhikari

    New Journal of Chemistry, ISSN: 11440546, eISSN: 13699261, Pages: 16999-17008, Published: 2018 Royal Society of Chemistry (RSC)
    Novel unsymmetrical star-shaped cyanopyridines were shown to possess an ordered hexagonal columnar assembly at room temperature. Their inherent intramolecular charge transport properties cause a technologically important intense blue light emission in the aggregated state.

  • Enhancing photovoltaic performance of DSSCs sensitized with Ru-II complexes by D-π-A configured carbazole based co-sensitizers
    Praveen Naik, Mohamed R. Elmorsy, Rui Su, Ahmed El-Shafei, and Airody Vasudeva Adhikari

    New Journal of Chemistry, ISSN: 11440546, eISSN: 13699261, Pages: 9443-9448, Published: 2018 Royal Society of Chemistry (RSC)
    Simple D–π–A architectured carbazole based dyes, P1–4, were employed as co-sensitizers in DSSCs sensitized with Ru-II complexes, viz.NCSU-10 and N3. The results revealed that, the NCSU-10 sensitized devices displayed improved photovoltaic performance when co-sensitized with P1 and P3.

  • New di-anchoring A-π-D-π-A configured organic chromophores for DSSC application: Sensitization and co-sensitization studies
    Praveen Naik, Rui Su, Mohamed R. Elmorsy, Ahmed El-Shafei, and Airody Vasudeva Adhikari

    Photochemical and Photobiological Sciences, ISSN: 1474905X, eISSN: 14749092, Pages: 302-314, Published: 2018 Royal Society of Chemistry (RSC)
    Three new metal-free carbazole based di-anchored dyes with A–π-D–π-A architecture (E1–3) were successfully designed, synthesized and characterized as potential photosensitizers. E1 displayed the highest photovoltaic performance, while E1–3 showed good VOC values when co-sensitized.

  • Synthesis, Characterization and Performance Studies of a New Metal-Free Organic Sensitizer for DSSC application
    Praveen Naik, Dickson D. Babu, Rui Su, Ahmed El-Shafei, and A. Vasudeva Adhikari

    Materials Today: Proceedings, eISSN: 22147853, Pages: 3150-3157, Published: 2018 Elsevier BV
    Abstract In this present work we report, design, synthesis and performance studies of a new metal-free organic dye (N, N’-PABA) based on N,N-dimethyl-4-vinyl aniline carrying 4-amino benzoic acid as acceptor, as sensitizers for sensitizing photoanode (TiO2). In the sensitizers, N,N-dimethylaniline ring acts as anelectron donorwhile para amino benzoic acid function as electron acceptor/anchoring units. It was synthesized via condensation reaction starting from simple 4-(N,N-dimethyl amino)benzaldehyde and their structures were confirmed using spectral techniques like FTIR, 1HNMR, 13CNMR, MS and elemental analysis. Further, it was subjected to electrochemical and optical characterization in order to evaluate their band gap and absorption/emission behavior. Further, DFT studies were performed using turbo mole V6.6 software package to evaluate their optimized geometry and FMO levels. Finally, DSSC devices were fabricated using this dye under simulated solar radiation AM1.5G and result revealed that it shows a conversion efficiency of 1%.

  • Hydrogen bond-driven columnar self-assembly of electroluminescent D-A-D configured cyanopyridones
    D. R. Vinayakumara, Hidayath Ulla, Sandeep Kumar, Anup Pandith, M. N. Satyanarayan, D. S. Shankar Rao, S. Krishna Prasad, and Airody Vasudeva Adhikari

    Journal of Materials Chemistry C, ISSN: 20507534, eISSN: 20507526, Pages: 7385-7399, Published: 2018 Royal Society of Chemistry (RSC)
    Flying bird-shaped cyanopyridone-based mesogens were designed and synthesized; their optoelectronic properties were studied in detail.

  • Improved photovoltaic performances of Ru (II) complex sensitized DSSCs by co-sensitization of carbazole based chromophores
    Praveen Naik, Rui Su, Ahmed El-Shafei, and Airody Vasudeva Adhikari

    Inorganic Chemistry Communications, ISSN: 13877003, Pages: 241-245, Published: December 2017 Elsevier BV
    Abstract Herein, we report photovoltaic performance studies of three carbazole based dyes (N1–3) derived from (Z)-3-(9-hexyl-9H-carbazol-3-yl)-2-(thiophen-2-yl)acrylonitrile scaffold as effective co-sensitizers in Ru (II) complex, i.e. NCSU-10 sensitized DSSCs. From the results it is evident that, the device fabricated using co-sensitizer N3 with 0.2 mM of NCSU-10 exhibited improved photon conversion efficiency (PCE) of 8.73% with JSC of 19.87 mA·cm− 2, VOC of 0.655 V and FF of 67.0%, while N1 displayed PCE of 8.29% with JSC of 19.75 mA·cm− 2, VOC of 0.671 V and FF of 62.6%, whereas NCSU-10 (0.2 mM) alone displayed PCE of 8.25% with JSC of 20.41 mA·cm− 2, VOC of 0.667 V and FF of 60.6%. However, their EIS studies confirm that, N1, showing higher VOC is efficient in suppressing the undesired charge recombination in DSSCs through enhanced surface coverage on TiO2 and thereby resulting in longer electron lifetime than that of NCSU-10 dye alone. Here, the higher PCE of N3 can be attributed to its improved light harvesting efficiency, which is due to the presence of highly electron withdrawing barbituric acid in its structure. Conclusively, the results showcase the potential of simple carbazole based dyes as co-sensitizers in improving efficiency of DSSCs.

  • Structurally simple D–A-type organic sensitizers for dye-sensitized solar cells: effect of anchoring moieties on the cell performance
    Praveen Naik, Rui Su, Dickson D. Babu, Ahmed El-Shafei, and Airody Vasudeva Adhikari

    Journal of the Iranian Chemical Society, ISSN: 1735207X, eISSN: 17352428, Pages: 2457-2466, Published: 1 November 2017 Springer Science and Business Media LLC
    In this work, we report synthesis and device fabrication studies of four metal-free D–A-type dyes (A1–A4) based on structurally simple N,N-dimethyl-4-vinyl aniline carrying four different acceptor/anchoring groups, as sensitizers for sensitizing photoanode (TiO2). In the sensitizers, N,N-dimethylaniline ring acts as an electron donor, while barbituric acid, N,N-dimethyl barbituric acid, thiobarbituric acid and N,N-diethyl thiobarbituric acid function as electron acceptor/anchoring units. They were synthesized in good yield via Knoevenagel protocol in neutral condition without any catalyst. Further, they were subjected to structural, electrochemical and optical characterization in order to evaluate their structure, band gap and absorption/emission behavior. The studies reveal that all the four dyes have thermodynamic feasibility of electron injection as well as electron recombination; their optical band gaps were found to be in the range of 2.35–2.56 eV. High-quality crystals of A2 and A4 were grown by slow evaporation technique using its solution with 1:1 pet ether (60–80 °C)/ethyl acetate solvent mixture at room temperature. Their SC-XRD studies disclose that the crystals are in the triclinic system with space group P-1. Further, DFT studies were performed using Turbomole V7.1 software package to evaluate their optimized geometry and HOMO and LUMO levels. Finally, DSSC device fabricated with the dye A1 showed relatively good efficiency when compared to other dyes mainly due to the effective binding of barbituric acid on the surface of TiO2 through NH or OH functional group.Graphical Abstract

  • Blue emitting 1,8-naphthalimides with electron transport properties for organic light emitting diode applications
    Hidayath Ulla, M. Raveendra Kiran, B. Garudachari, T.N. Ahipa, Kartick Tarafder, Airody Vasudeva Adhikari, G. Umesh, and M.N. Satyanarayan

    Journal of Molecular Structure, ISSN: 00222860, Volume: 1143, Pages: 344-354, Published: 5 September 2017 Elsevier BV
    Abstract In this article, the synthesis, characterization and use of two novel naphthalimides as electron-transporting emitter materials for organic light emitting diode (OLED) applications are reported. The molecules were obtained by substituting electron donating chloro-phenoxy group at the C-4 position. A detailed optical, thermal, electrochemical and related properties were systematically studied. Furthermore, theoretical calculations (DFT) were performed to get a better understanding of the electronic structures. The synthesized molecules were used as electron transporters and emitters in OLEDs with three different device configurations. The devices with the molecules showed blue emission with efficiencies of 1.89 cdA -1 , 0.98 lmW −1 , 0.71% at 100 cdm -2 . The phosphorescent devices with naphthalimides as electron transport materials displayed better performance in comparison to the device without any electron transporting material and were analogous with the device using standard electron transporting material, Alq 3 . The results demonstrate that the naphthalimides could play a significant part in the progress of OLEDs.

  • Molecular design and theoretical investigation of new metal-free heteroaromatic dyes with D-π-A architecture as photosensitizers for DSSC application
    Praveen Naik, Rui Su, Mohamed R. Elmorsy, Dickson D. Babu, Ahmed El-Shafei, and Airody Vasudeva Adhikari

    Journal of Photochemistry and Photobiology A: Chemistry, ISSN: 10106030, Volume: 345, Pages: 63-73, Published: 1 August 2017 Elsevier BV
    Abstract Herein, we report design, synthesis and photovoltaic performance of four new metal-free heteroaromatic dyes ( P 1-4 ) with D-π-A architecture carrying electron donating carbazole core connected to four different electron withdrawing/anchoring groups, viz. cyanoacetic acid, rhodanine-3-acetic acid, barbituric acid and thiobarbituric acid and phenylene ring as a π-spacer. The newly designed P 1-4 were synthesized from carbazole derivative using Suzuki cross coupling approach followed by Knoevenagel condensation reaction. Their structures were confirmed by FTIR, NMR, Mass spectral and elemental analyses. The dyes were subjected to optical and electrochemical studies in order to investigate their absorption/emission behavior as well as HOMO/LUMO energies. The UV–vis spectral studies reveal that the P 1-4 showed λ max at 412, 439, 458 and 489 nm, respectively. Their optical band-gap is in the range of 2.17 to 2.61 eV and fluorescence quantum yield is in the order of 44–70%. From energy level diagram, it is clear that all the dyes possess good thermodynamic feasibility for electron injection into CB edge of TiO 2 as well as their regeneration from electrolyte system. The photovoltaic performance studies indicate that among the tested dyes, P 1 anchored with cyanoacetic acid displayed the highest IPCE (32%), resulting in improved PCE (1.94%), J SC (4.68 mA cm −2 ), V OC (0.588 V) and FF (70.3%) values, when compared to other dyes. Finally, DFT studies were performed using Turbomole 7.1 V software to investigate their electron cloud delocalization in HOMO/LUMO levels and theoretical absorption spectral data. The results reveal that the dye P 1 showed effective charge separation in its FMO levels, which has reflected in its ICT behavior and hence P 1 displayed the improved photovoltaic performance.

  • Synthesis and photovoltaic performance of a novel asymmetric dual-channel co-sensitizer for dye-sensitized solar cell beyond 10% efficiency
    Dickson D. Babu, Rui Su, Praveen Naik, Ahmed El-Shafei, and Airody Vasudeva Adhikari

    Dyes and Pigments, ISSN: 01437208, eISSN: 18733743, Volume: 141, Pages: 112-120, Published: 1 June 2017 Elsevier BV
    Abstract In this paper, we report the design and synthesis of a new bi-anchoring indole based co-sensitizer DBA-8 with A-π-D-A (acceptor-π bridge-donor-acceptor) architecture, carrying indole moiety as a donor and barbituric acid as acceptor/anchoring groups. Its photo-physical and electrochemical properties along with molecular geometries, calculated from Density Functional Theory (DFT) are employed to comprehend the effect of co-sensitizer structure on photovoltaic characteristics of DSSCs. The abovementioned organic dye ( DBA-8 ) was employed as a co-sensitizer along with well-known ruthenium based sensitizer NCSU-10 in order to broaden the spectral responses of the co-sensitized DSSC. In the present work, for the first time we are demonstrating the profound role of a dual-anchoring co-sensitizer that can play in ameliorating the overall performance of a solar cell. The photovoltaic studies indicated that, the co-sensitizer DBA-8 succeeded in increasing the light harvesting ability in the device significantly. Notably, the device co-sensitized using 0.2 mM DBA-8 along with ruthenium based chromophore NCSU-10 , showed a maximum efficiency of 10.68% ( J sc  = 25.14 mAcm −2 , V oc  = 0.695 V, ff  = 61.2%). Further, the good agreement between the theoretically and experimentally obtained λ max data vindicate that, the energy functional and basis set employed in this study can be successfully utilized for predicting the absorption spectra of new photosensitizers, with great precision before synthesis. Furthermore, all these findings showcase the vast potential of bi-anchoring molecules in improving the overall performance of the dye-sensitized solar cells.

  • Exploring the application of new carbazole based dyes as effective p-type photosensitizers in dye-sensitized solar cells
    Praveen Naik, Aurélien Planchat, Yann Pellegrin, Fabrice Odobel, and Airody Vasudeva Adhikari

    Solar Energy, ISSN: 0038092X, Volume: 157, Pages: 1064-1073, Published: 2017 Elsevier BV
    Abstract Herein, we report the design and the synthesis of three new D-A type metal-free carbazole based dyes (C1–3) as effective photosensitizers for p-type DSSCs. In this new design, the electron rich carboxy substituted carbazole unit has been attached to three different electron withdrawing species, viz. N,N-dimethyl barbituric acid, N,N-diethyl thiobarbituric acid and N-ethyl rhodanine. They were well-characterized by spectral, photophysical and electrochemical analyses. Further, their optical and electrochemical parameters along with molecular geometries, optimized from DFT have been employed to apprehend the effect of structures of C1–3 on their photovoltaic performances. Further, the photovoltaic performance of C1–3 was determined along with the standard dye P1 and their PCE values were found to be in the order of P1 (0.047%) > C2 (0.040%) > C1 (0.016%) > C3 (0.001%). Interestingly, the NiO based p-type DSSC fabricated with C2 carrying electron withdrawing N,N-diethyl thiobarbituric acid displayed VOC as 59 ± 4 mV and FF as 29 ± 1%, which are higher than that of benchmark reference P1. This is attributed to the highest light harvesting ability, the greatest regeneration driving force and the lowest interfacial charge recombination of C2 among the tested dyes. Conclusively, the results showcase the potential of carbazole based D-A type sensitizers in the development of efficient p-type DSSCs.

  • New carbazole based metal-free organic dyes with D-Π-A-Π-A architecture for DSSCs: Synthesis, theoretical and cell performance studies
    Praveen Naik, Mohamed R. Elmorsy, Rui Su, Dickson D. Babu, Ahmed El-Shafei, and Airody Vasudeva Adhikari

    Solar Energy, ISSN: 0038092X, Volume: 153, Pages: 600-610, Published: 2017 Elsevier BV
    Abstract Herein we report the design, synthesis and photovoltaic performance studies of three new D-π-A-π-A architectured organic chromophores (N1-3) derived from (Z)-3-(9-hexyl-9H-carbazol-3-yl)-2-(thiophen-2-yl) acrylonitrile scaffold. In the new design, the electron rich carbazole unit is connected to three different electron withdrawing/anchoring species, viz. cyano acetic acid, rhodanine-3-acetic acid and barbituric acid via cyano vinyl thiophene as π-spacer. Newly synthesized dyes were characterized by spectral, photophysical and electrochemical analyses. Their optical band-gap, GSOP and ESOP values, as calculated from the optical and CV studies were found to be in the range of 2.12–2.21, −5.52 to −5.43 and −5.40 to −3.25 eV respectively. The DFT and TD-DFT studies were performed using Turbomole 7.1V software and the results indicated the existence of proper charge separation between HOMO and LUMO levels of the dyes. Also, the results revealed good matching of theoretically generated optical spectral data with the experimental values. Finally, DSSC devices were fabricated using these three dyes and the dye N1 containing cyanoacetic acid as an acceptor unit showed better photo conversion efficiency (η) of 3.55% than the other two dyes. It’s JSC, VOC, and IPCE parameters were shown to be 9.06 mA cm−2, 0.577 V and 48%, respectively. The obtained EIS data and electron lifetimes of N1–3 sensitized devices are well in accordance with experimental photovoltaic parameters.

  • Highly efficient panchromatic dye-sensitized solar cells: Synergistic interaction of ruthenium sensitizer with novel co-sensitizers carrying different acceptor units
    Dickson D. Babu, Dalia Elsherbiny, Hammad Cheema, Ahmed El-Shafei, and Airody Vasudeva Adhikari

    Dyes and Pigments, ISSN: 01437208, eISSN: 18733743, Volume: 132, Pages: 316-328, Published: 1 September 2016 Elsevier BV
    Abstract Herein, we report the molecular design, synthesis and photovoltaic performance studies of three new organic co-sensitizers, N1-3 carrying indole and thiophene units linked to different acceptors/anchoring groups, as co-adsorbents for dye sensitized solar cells. We present the role of anchoring/acceptor units on co-sensitization properties N1-3. Their photo-physical and electrochemical results along with molecular geometry, obtained from Density Functional Theory are utilized to rationalize the influence of co-sensitizer structures on photovoltaic properties for DSSCs. We have shown that, the co-sensitization effect is profoundly dependent upon the anchoring/acceptor unit in the co-adsorbents. Among them, N3 containing 4-aminobenzoic acid shows promising co-sensitization results and exhibits an enhanced efficiency of 9.26%, when co-sensitized with a ruthenium dye, HD-14. Further, the study highlights the importance of molecular matching between the sensitizer and co-sensitizer in enhancing the efficiency. Furthermore, vertical electronic excitations are calculated using time dependent density functional theory studies.

  • Green Synthesis of Silver and Gold Nanoparticles Using Root Bark Extract of Mammea suriga: Characterization, Process Optimization, and Their Antibacterial Activity
    Mahesha M. Poojary, Paolo Passamonti, and Airody Vasudeva Adhikari

    BioNanoScience, ISSN: 21911630, eISSN: 21911649, Pages: 110-120, Published: 1 June 2016 Springer Science and Business Media LLC
    The present study reports the green synthesis of silver and gold nanoparticles (NPs) from their respective precursors AgNO3 and HAuCl4, using root bark extract of Mammea suriga. Further, it describes the influence of various reaction parameters, such as pH, temperature, precursor concentration, and volume of the extract, on the morphology and size of the newly synthesized NPs. The biosynthesized NPs were characterized using UV–Vis spectroscopy, SEM, EDX, XRD, and FTIR. The formation of Ag and Au NPs was confirmed by their UV–Vis spectra. Ag NPs were efficiently synthesized at pH 10, with precursor concentration of 1 mM of AgNO3 and a reaction temperature of 80 °C, while Au NPs were successfully obtained at pH 8, with precursor concentration of either 1 or 3 mM HAuCl4, and the reaction was maintained at room temperature. The SEM study revealed that the particle size decreases with an increase in the extract volume used in the reaction. The XRD analysis confirmed the formation of metallic Ag and Au NPs having an average size of 50 and 22 nm, respectively. Further, the FTIR spectral data established the role of various functional groups of biomolecules involved in bioreduction as well as capping of NPs. The in vitro antibacterial screening results indicated that the NPs are potential antibacterial agents. Conclusively, the overall study showed that the root bark extract of M. suriga is an excellent eco-friendly and non-toxic source for the synthesis of biologically active Ag and Au NPs at optimal conditions.

  • From Molecular Design to Co-sensitization; High performance indole based photosensitizers for dye-sensitized solar cells
    Dickson D. Babu, Rui Su, Ahmed El-Shafei, and Airody Vasudeva Adhikari

    Electrochimica Acta, ISSN: 00134686, Volume: 198, Pages: 10-21, Published: 20 April 2016 Elsevier BV
    Herein, we report the molecular design and synthesis of two novel organic co-adsorbers DBA-1((Z)-2-cyano-3-(5-(4-(cyclohexa-1,5-dien-3-ynyl(phenyl)amino)phenyl)-1-hexyl-1H-indol-3-yl)acrylic acid) and (DBA-2) 5-((5-(4-(diphenylamino)phenyl)-1-hexyl-1H-indol-3-yl)methylene)pyrimidine-2,4,6(1H,3H,5H)-trione with D-D-A (donor-donor-acceptor) architecture. We have combined the strong electron donating triphenylamine group with indole moiety attached to different acceptors/anchoring groups, as co-adsorbers for dye-sensitized solar cells and we present for the first time, the role of anchoring/acceptor unit on their co-adsorption properties. In this study, cyanoacetic acid and barbituric acid are employed as anchoring groups in the co-sensitizers DBA-1 and DBA-2, respectively. Their electrochemical and photo-physical properties along with molecular geometries, obtained from Density Functional Theory (DFT) are employed to vindicate the effect of co-sensitizer structures on photovoltaic properties of DSSCs. We have demonstrated that the co-sensitization effect is profoundly dependent upon the anchoring/acceptor unit in the co-adsorber molecule. Devices co-sensitized using DBA-1 and DBA-2 along with HD-2 (Ru-complex of 4, 4'-bis-(1,4-benzodioxan-5-yl-vinyl)-[2,2']bipyridine), displayed higher power conversion efficiencies (PCEs) than the device sensitized using only HD-2. In the present work, ruthenium based sensitizer, HD-2, has been chosen due to its better solar-to-power conversion efficiency and impressively higher photocurrent densities than that of standard N719. Among them, co-adsorber DBA-2, containing barbituric acid as the acceptor/anchoring group displays promising photovoltaic results and exhibited an enhanced efficiency of 8.06%. Further, good agreement between the calculated and experimental results showcase the precision of the energy functional and basis set utilized in this study. All these findings provide a deeper insight and better understanding into the intricacies involved in the design of superior co-sensitizers for development of highly efficient DSSCs.

  • “Dental Cements Based on Acid Degradable Glasses/Ion Leachable Glasses” – A Review
    P. Nagaraja Upadhya, Kishore Ginjupalli, K. K. Srinivasan, A. V. Adhikari, and L. N. Satapathy

    Transactions of the Indian Ceramic Society, ISSN: 0371750X, eISSN: 21655456, Pages: 83-91, Published: 2 April 2016 Informa UK Limited
    ABSTRACT Glass ionomer cement (GIC) is one of the most versatile cements used in dentistry. It came into existence in the late 1960s mainly to overcome the drawbacks of its predecessor material ‘dental silicate cements’. Since then, it has undergone several improvisations and modifications to meet the requirements of various dental applications. The GIC consists of basic glass powder and acidic polyacids, which sets by an acid-base reaction between the components. The glass component of GIC plays a major role in the clinical performance of the material. It provides the source of ions for the cement formation, controls the strength, imparts translucency and provides a therapeutic benefit by releasing fluoride. Glass structure-reactivity-processing are the three main aspects to be considered when designing the glass compositions for cement formation. From the conventional calcium fluoroaluminosilicate glass to the current aluminium free glasses, GIC has received significant attention in the recent past to further extend its applications in various fields. The purpose of this article is to provide relevant discussion on the scientific development of the GIC from the glass science and technology point of view. GRAPHICAL ABSTRACT

  • Molecular engineering and theoretical investigation of metal-free organic Chromophores for dye-sensitized solar cells
    DicksonD. Babu and A. Vasudeva Adhikari

    Advanced Science Letters, ISSN: 19366612, eISSN: 19367317, Pages: 36-39, Published: January 2016 American Scientific Publishers

  • New indole based co-sensitizers for dye sensitized solar cells exceeding 10% efficiency
    Dickson D. Babu, Rui Su, Ahmed El-Shafei, and Airody Vasudeva Adhikari

    RSC Advances, eISSN: 20462069, Pages: 30205-30216, Published: 2016 Royal Society of Chemistry (RSC)
    In this work, we report the molecular engineering and synthesis of three novel indole co-sensitizers DBA-3, DBA-4 and DBA-5 with D–D–A (donor–donor–acceptor) architecture.

  • Photo tuning of thiophene-2,5-dicarbohydrazide derivatives for their photoalignment ability-molecular modelling studies
    Gurumurthy Hegde, A. A. Murausky, A. A. Murauski, I. N. Kukhta, A. V. Adhikari, and L. Komitov

    RSC Advances, eISSN: 20462069, Pages: 79800-79806, Published: 4 September 2015 Royal Society of Chemistry (RSC)
    Simple way of tuning the photo alinging layers.

  • Molecular Engineering and Theoretical Investigation of Novel Metal-Free Organic Chromophores for Dye-Sensitized Solar Cells
    Dickson D. Babu, Hammad Cheema, Dalia Elsherbiny, Ahmed El-Shafei, and Airody Vasudeva Adhikari

    Electrochimica Acta, ISSN: 00134686, Volume: 176, Pages: 868-879, Published: 1 August 2015 Elsevier BV
    Abstract In this work we report design and synthesis of three new metal free D-D–A–π–A type dyes ( E 1-3 ) with different acceptor/anchoring groups, as effective sensitizers for nanocrystalline titanium dioxide based dye sensitized solar cells. All the three dyes carry electron donating methoxy group as an auxiliary and indole as a principal donor, cyanovinylene as an auxiliary acceptor and thiophene as a π-spacer. Whereas, cyanoacetic acid, rhodanine-3-acetic acid and 4-aminobenzoic acid perform as acceptor/anchoring moieties, respectively in the dyes E 1-3 . Though the dye containing 4-aminobenzoic acid unit ( E 3 ) exhibits comparatively lower λ max , it shows the highest power conversion efficiency arising from the higher electron life time and good light-harvesting capability. The DFT studies reveal a better charge separation between the HOMO and LUMO levels of E 3 , further substantiating the experimental results. Among the three dyes, E 3 shows the best photovoltaic performance with short-circuit current density (J sc ) of 9.35 mA cm −2 , open-circuit voltage (V oc ) of 620 mV and fill factor (FF) of 0.71, corresponding to an overall conversion efficiency of 4.12% under standard global AM 1.5G.

  • Extraction, characterization and biological studies of phytochemicals from Mammea suriga
    Mahesha M. Poojary, Kanivebagilu A. Vishnumurthy, and Airody Vasudeva Adhikari

    Journal of Pharmaceutical Analysis, ISSN: 20951779, Pages: 182-189, Published: 1 June 2015 Elsevier BV
    The present work involves extraction of phytochemicals from the root bark of a well-known Indian traditional medicinal plant, viz. Mammea suriga, with various solvents and evaluation of their in vitro antimicrobial and antioxidant activities using standard methods. The phytochemical analysis indicates the presence of some interesting secondary metabolites like flavonoids, cardiac glycosides, alkaloids, saponins and tannins in the extracts. Also, the solvent extracts displayed promising antimicrobial activity against Staphylococcus aureus, Bacillus subtilis and Cryptococcus neoformans with inhibition zone in a range of 20–33 mm. Further, results of their antioxidant screening revealed that aqueous extract (with IC50 values of 111.51±1.03 and 31.05±0.92 μg/mL in total reducing power assay and DPHH radical scavenging assay, respectively) and ethanolic extract (with IC50 values of 128.00±1.01 and 33.25±0.89 μg/mL in total reducing power assay and DPHH radical scavenging assay, respectively) were better antioxidants than standard ascorbic acid. Interestingly, FT-IR analysis of each extract established the presence of various biologically active functional groups in it.

  • New D-π-A type indole based chromogens for DSSC: Design, synthesis and performance studies
    Dickson D. Babu, Saritha Reddy Gachumale, Sambandam Anandan, and Airody Vasudeva Adhikari

    Dyes and Pigments, ISSN: 01437208, Volume: 112, Pages: 183-191, Published: January 2015 Elsevier BV
    Abstract Three new Donor-π-Acceptor type dyes D 1–3 carrying 3-(1-hexyl-1 H -indol-3-yl)-2-(thiophen-2-yl)acrylonitrile as backbone with three different acceptor units were designed and synthesized as promising sensitizers for solar cell application. The new dyes were characterized using various spectral and elemental analyses. Their optical and electrochemical properties were investigated using spectrophotometry and cyclic voltammetry respectively, while their photovoltaic performance was evaluated by a device fabrication study. The devices were subjected to electrochemical impedance spectroscopy to gain an insight into the interfacial charge transfer and recombination process while in use. Further, density functional theory study was carried out to investigate their Frontier Molecular Orbital energy states. The study reveals that the dye carrying 4-aminobenzoic acid as an acceptor showed the highest photovoltaic efficiency among the three dyes. This can be attributed to the longer electron lifetime and lower recombination rates. Additionally, a Single crystal X-ray diffraction study confirmed the structure of a key intermediate.

  • New cyanopyridone based luminescent liquid crystalline materials: Synthesis and characterization
    Ahipa T. N. and Airody Vasudeva Adhikari

    Photochemical and Photobiological Sciences, ISSN: 1474905X, eISSN: 14749092, Pages: 1496-1508, Published: 1 November 2014 Royal Society of Chemistry (RSC)
    A series of new luminescent mesogens carrying cyanopyridone, triazole, and polar groups were successfully synthesized. Also, their liquid crystalline and photophysical properties were investigated.

  • 2-Methoxypyridine derivatives: Synthesis, liquid crystalline and photo-physical properties
    Ahipa T. N. and Airody Vasudeva Adhikari

    New Journal of Chemistry, ISSN: 11440546, eISSN: 13699261, Pages: 5018-5029, Published: 1 October 2014 Royal Society of Chemistry (RSC)
    Design and synthesis of fourteen new bent shaped luminescent mesogens carrying a pyridine core with various polar substituents are reported.

  • New 4-(2-(4-alkoxyphenyl)-6-methoxypyridin-4-yl)benzonitriles: Synthesis, liquid crystalline behavior and photo physical properties
    T. N. Ahipa, Vijith Kumar, D. S. Shankar Rao, Subbarao Krishna Prasad, and Airody Vasudeva Adhikari

    CrystEngComm, eISSN: 14668033, Pages: 5573-5582, Published: 7 July 2014 Royal Society of Chemistry (RSC)
    A new series of luminescent 4-(2-(4-alkoxyphenyl)-6-methoxypyridin-4-yl)benzonitriles containing three ring systems, with bent-core structures was synthesized as potential mesogens and characterized by spectral techniques.

  • New luminescent 2-methoxy-6-(4-methoxy-phenyl)-4-p-tolyl-nicotinonitrile: Synthesis, crystal structure, DFT and photophysical studies
    T.N. Ahipa, Pooja R. Kamath, Vijith Kumar, and Airody Vasudeva Adhikari

    Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, ISSN: 13861425, Volume: 124, Pages: 230-236, Published: 24 April 2014 Elsevier BV
    In the current communication, we report the synthesis, spectroscopic, crystal structure, DFT and photophysical studies of a new nicotinonitrile derivative, viz. 2-methoxy-6-(4-methoxy-phenyl)-4-p-tolyl-nicotinonitrile (2) as a potential blue light emitting material. The compound 2 was synthesized in good yield via a simple route. The acquired spectral and elemental analysis data were in consistent with the chemical structure of 2. The single crystal study further confirms its three dimensional structure, molecular shape, and nature of short contacts. Its DFT calculations reveal that compound 2 possesses a non-planar structure and its theoretical IR spectral data are found to be in accordance with experimental values. In addition, its UV-visible and fluorescence spectral measurements prove that the compound exhibits good absorption and fluorescence properties. Also, it shows positive solvatochromic effect when the solvent polarity was varied from non-polar to polar.

  • Trihydrazone functionalized cyanopyridine discoids: Synthesis, mesogenic and optical properties
    T.N. Ahipa and Airody Vasudeva Adhikari

    Tetrahedron Letters, ISSN: 00404039, eISSN: 18733581, Pages: 495-500, Published: 8 January 2014 Elsevier BV
    Abstract A new series of trihydrazone functionalized cyanopyridine derivatives ( CPTH-D m ) carrying 3,4-dialkoxyphenyl groups was designed and synthesized successfully as discotic columnar liquid crystals. These new discoid mesogens display hexagonal columnar phase with a wide mesophase range from ambient temperature to 110 °C and the observed columnar assembly is due to the presence of intermolecular hydrogen bonds and π–π interactions in them. Their optical studies reveal that the compounds are good blue light emitters and hence they are potential candidates for OLED device fabrication.

  • New columnar liquid crystal materials based on luminescent 2-methoxy-3-cyanopyridines
    T. N. Ahipa, Vijith Kumar, and Airody Vasudeva Adhikari

    Structural Chemistry, ISSN: 10400400, Pages: 1165-1174, Published: August 2014 Springer Science and Business Media LLC
    Abstract A new series of donor–acceptor–donor (D–A–D) type luminescent mesogens carrying 2-methoxy-3-cyanopyridine as a central core linked with variable alkoxy chain lengths (m = 6 and 8) as terminal substituents was synthesized and characterized using spectral methods. The newly synthesized molecules were subjected to single-crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), differential scanning calorimetric (DSC), polarizing optical microscopy (POM), and fluorescence emission studies in order to ascertain their mesogenic and photophysical properties. The SCXRD data on 4a and 4b reveal that the presence of short intermolecular contacts, viz. C–H···N, C–H···O, C–H···π, and π···π interactions, is responsible for their crystal packing. The measured torsion angle values indicate that molecules possess distorted non-planar structure. The DSC, POM, and PXRD studies confirm that all the molecules show thermotropic liquid crystalline behaviour and exhibit rectangular columnar phase. Further, their UV–visible and fluorescence spectral studies reveal that the target molecules are luminescent displaying a strong absorption band in the range of 335–340 nm and a blue fluorescence emission band in the range of 395–425 nm (both in solution and film state) with good fluorescence quantum yields (10–49 %).

  • New 6-bromoimidazo[1,2-A]pyridine-2-carbohydrazide derivatives: Synthesis and anticonvulsant studies
    Shrikanth Ulloora, Ramakrishna Shabaraya, and Airody Vasudeva Adhikari

    Medicinal Chemistry Research, ISSN: 10542523, eISSN: 15548120, Pages: 3019-3028, Published: June 2014 Springer Science and Business Media LLC
    In the present work, we report the facile synthesis and anticonvulsant study of new imidazo[1,2-a]pyridines carrying biologically active hydrazone functionality (3a–3e) and suitably substituted 1,2,4-triazole moieties (4, 5a–5d, 6, and 7a–7d). The newly synthesized intermediates and final compounds were characterized by various spectral techniques such as FTIR, 1H NMR, 13C NMR, and mass spectral and elemental analysis studies. The in vivo anticonvulsant study of the target compounds were carried out following maximal electroshock seizure and subcutaneous pentylene tetrazole methods, while their toxicity study was performed following rotarod method by taking 20, 40, and 100 mg/kg dose levels. Most of the new compounds displayed remarkable anticonvulsant properties at these doses. Particularly, compounds 3b and 4 carrying hydrogen bond donor groups, viz. hydroxyl and amine moieties respectively, exhibited complete protection against seizure and their results are comparable to that of standard drug diazepam. Further, the motor impairment study revealed that all the compounds are nontoxic upto 100 mg/kg.

  • Synthesis and antiepileptic studies of new imidazo[1,2-a]pyridine derivatives
    Shrikanth Ulloora, Airody Vasudeva Adhikari, and Ramakrishna Shabaraya

    Chinese Chemical Letters, ISSN: 10018417, Pages: 853-856, Published: September 2013 Elsevier BV
    Abstract In this manuscript, we report the synthesis of newly designed imidazo[1,2-a]pyridines carrying active pharmacophores as potential anticonvulsant agents. Newly synthesized target compounds were characterized by FTIR, 1 H NMR, 13 C NMR, and mass spectroscopy followed by elemental analysis studies. Preliminary anticonvulsant screening study of target compounds was carried out following MES and scPTZ methods. Compounds 6e and 6f , possessing electron rich aryl substituent at position-2 and tolyl substituted oxazolone moiety at the position-3 of imidazo[1,2-a]pyridine ring, exhibited activity comparable to standard drug diazepam and emerged as lead compounds. New compounds displayed enhanced activity in scPTZ method, indicating their ability to raise the seizure threshold. Their neurotoxicity study by Rotarod test showed that they are nontoxic at all tested doses.

  • Optical limiting materials: Synthesis, electrochemical and optical studies of new thiophene based conjugated polymers carrying 1,3,4-oxadiazole units
    Sunitha M. Shivashankar, Vishnumurthy K. Anantapadmanabha, and Airody Vasudeva Adhikari

    Polymer Engineering and Science, ISSN: 00323888, eISSN: 15482634, Pages: 1347-1356, Published: June 2013 Wiley
    In this communication we report synthesis of three new donor-acceptor (D–A) type conjugated polymers carrying 1,3,4-oxadiazole moiety and thiophene unit with different side groups at its 3,4 positions (4-methoxybenzyl:P1, 3-methylbenzyl:P2 and 4-nitrobenzyl:P3) through polycondensation route using a series of newly synthesized monomers. The structures of new monomers and polymers were confirmed by NMR, FTIR spectroscopic methods followed by elemental analysis. Further, molecular weight and thermal stability were determined using gel permeation chromatography and thermogravimetric analysis. The linear optical and electrochemical properties of polymers were investigated by UV–vis absorption, fluorescence spectroscopic, and cyclic voltammetric studies. The polymers P1–P3 were found to be thermally stable and their electrochemical band gaps were determined to be 1.98, 2.14, and 2.18 eV respectively. Further their nonlinear optical properties were investigated by Z-scan method using 532 nm, 7 ns laser pulses. The results reveal that they possess good optical limiting behavior due to effective three-photon absorption (3PA) with absorption coefficient 2.5 × 10−24 m−3W2, 1.6 × 10−24 m−3W2, and 1.0 × 10−24 m−3W2. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers

  • Facile synthesis of new imidazo[1,2-a]pyridines carrying 1,2,3-triazoles via click chemistry and their antiepileptic studies
    Shrikanth Ulloora, Ramakrishna Shabaraya, and Airody Vasudeva Adhikari

    Bioorganic and Medicinal Chemistry Letters, ISSN: 0960894X, eISSN: 14643405, Pages: 3368-3372, Published: 1 June 2013 Elsevier BV
    The present article reports the synthesis and anticonvulsant studies of new 2-arylimidazo[1,2-a]pyridines carrying suitably substituted 1,2,3-triazoles as well as their intermediates. The structures of newly synthesized compounds were confirmed by various spectroscopic techniques. The anticonvulsant study was carried out by MES and scPTZ screening methods, while their toxicity study was performed following Rotarod method. The active compounds showed enhanced seizure control in scPTZ method when compared with that of MES method. Compounds 3f, 4c, 4f, 5k, 5p and 5w carrying active pharmacophores exhibited complete protection against seizure and their results were comparable with standard drug diazepam. Majority of new compounds were found to be non-toxic, while few of them showed toxicity at 100 mg/kg. The clogP values of target compounds are in the range of 3.5-5.3, which confirm their lipophilic nature.

  • New dihydropyridine derivatives: Anti-inflammatory, analgesic and docking studies
    Shrikanth Ulloora, Santhosh Kumar, Ramakrishna Shabaraya, and Airody Vasudeva Adhikari

    Medicinal Chemistry Research, ISSN: 10542523, eISSN: 15548120, Pages: 1549-1562, Published: April 2013 Springer Science and Business Media LLC
    The present article describes synthesis of new diethyl 2,6-dimethyl-4-(4-(2-substituted amino-2-oxoethoxy) phenyl)-1,4-dihydropyridine-3,5-dicarboxylates (6a–10b) following multistep synthetic route. Structures of newly synthesized intermediates and title compounds were established by spectral and elemental analyses. The final compounds were screened for their in vivo anti-inflammatory and analgesic activities by carrageenan-induced paw oedema and tail immersion methods, respectively. Moreover, molecular docking studies were carried out for active compounds 6c, 6d, 7d, 8 and 10b to study their mode of action, meanwhile in vivo results indicated that these compounds displayed rapid onset of anti-inflammatory action and exhibited prominent activity when compared with the standard drug. Compounds 6d and 7d carrying amide functionality showed the highest anti-inflammatory as well as analgesic activities. The molecular docking results emphasised the in vivo data and all docked molecules were found to display very low binding constant values in nanomolar scale.

  • New imidazo[1,2-a]pyridines carrying active pharmacophores: Synthesis and anticonvulsant studies
    Shrikanth Ulloora, Ramakrishna Shabaraya, Syed Aamir, and Airody Vasudeva Adhikari

    Bioorganic and Medicinal Chemistry Letters, ISSN: 0960894X, eISSN: 14643405, Pages: 1502-1506, Published: 1 March 2013 Elsevier BV
    Five new series of imidazo[1,2-a]pyridines carrying biologically active pyrazoline (4a-e), cyanopyridone (5a, b), cyanopyridine (6a-f), 2-aminopyrimidine (7a-f) and pyrimidine-2-thione (8a-d) systems were designed and synthesized as prominent anticonvulsant agents. The target compounds were screened for their in vivo anticonvulsant activity following maximal electroshock (MES) and subcutaneous pentylene tetrazole (scPTZ) methods at a small test dose of 10 mg/kg. Further, Rotarod toxicity method was used to study the toxicity profile of selected compounds. Compounds 4b, 5a, 5b, 6a, 7e and 8d possessing 4-fluorophenyl substituent at 2nd position of imidazo[1,2-a]pyridine ring displayed potent anticonvulsant activity without displaying any toxicity. Enhanced activity profile was observed for new compounds in PTZ method over MES method.

  • Synthesis and two-photon absorption property of new π -conjugated donor-acceptor polymers carrying different heteroaromatics
    M S SUNITHA, K A VISHNUMURTHY, and A V ADHIKARI

    Journal of Chemical Sciences, ISSN: 09743626, eISSN: 09737103, Volume: 125, Pages: 29-40, Published: January 2013 Springer Science and Business Media LLC
    AbstractIn this communication, we report the synthesis of three newly designed fluorescent polymers P1–P3, starting from simple thiophene derivatives through precursor polyhydrazide route. The new polymers, carrying donor and acceptor heterocyclic moieties with different spacer groups were found to be thermally stable and good of nonlinear optical (NLO) materials with two photon absorption property. The structures of newly synthesized monomers and polymers were confirmed by FTIR, NMR spectral and elemental analyses. Further, polymers were characterized by GPC and TGA studies. Their linear optical and electrochemical properties were evaluated by UV-vis, fluorescence spectroscopic and cyclic voltammetric (CV) studies, respectively, whereas their NLO properties were studied by Z-scan technique using Nd: YAG laser at 532 nm with 7 ns pulse. The electrochemical band gap of P1–P3 was determined to be 1.98, 1.91 and 2.05 eV, respectively. The NLO results reveal that polymers P1–P3 show good optical limiting property with TPA coefficient values 2.9 × 10 − 11 m/W, 8.0 × 10 − 11 m/W and 1.4 × 10 − 11 m/W, respectively. Graphical AbstractThis paper focuses on synthesis of new donor–acceptor (D–A) conjugated polymers with different spacer groups and their influence on electrochemical, linear and nonlinear optical properties.

  • Synthesis, structural analysis and solvatochromic behaviour of 4,6-bis (4-butoxyphenyl)-2-methoxynicotinonitrile mesogen
    T.N. Ahipa, Vijith Kumar, and Airody V. Adhikari

    Liquid Crystals, ISSN: 02678292, eISSN: 13665855, Pages: 31-38, Published: January 2013 Informa UK Limited
    In this communication, we report the synthesis and characterisation of a new luminescent liquid crystalline material, 4,6-bis (4-butoxyphenyl)-2-methoxynicotinonitrile (3). We have confirmed its structure by Fourier transform infrared and 1H nuclear magnetic resonance spectroscopy, elemental analysis and X-ray single crystal diffraction studies. The newly synthesised compound crystallises in a monoclinic system with the space group C2/c and its cell parameters are found to be a = 25.181(4) Å, b = 15.651(4)Å, c = 12.703(19) Å, V = 4880.4 (16) Å, Z = 8. The results indicate that the presence of weak CH … O and CH … N hydrogen bonding as short-range intermolecular interactions are responsible for the formation of its crystal assembly. The measured torsion angle shows the existence of a distorted structure for the molecule wherein 4-butoxyphenylene ring substituent at the fourth position of the central pyridine ring forms a torsion angle χ[C(4), C(3), C(10), C(19)] of 40.55°. Its liquid crystalline behaviour was investigated with the aid of polarised optical microscopy and differential scanning calorimetry. The study reveals that the compound displays a broad nematic phase in the range of 78–112°C. Further, solution phase optical studies indicate that it is a blue light emitter in different non-polar and polar organic solvents at a concentration of 10−5M.

  • Synthesis and characterization of thiophene-based donor-acceptor type polyimide and polyazomethines for optical limiting applications
    K. A. Vishnumurthy, M. S. Sunitha, and A. Vasudeva Adhikari

    Polymer Bulletin, ISSN: 01700839, Pages: 147-169, Published: January 2013 Springer Science and Business Media LLC
    In this communication we describe the design and synthesis of four new conjugated polymers (P1–P4) based on 3,4-ditetradecyloxythiophene. The required diamine monomer was prepared by a unique catalyst-free reduction process using hydrazine hydrate. The structures of the intermediates and polymers were established by FTIR, 1H NMR spectroscopy. Molecular weights of polymers were determined by gel permeation chromatographic (GPC) method. Their electrochemical properties were investigated by cyclic voltammetry and linear optical properties were determined by UV–Visible absorption and fluorescence emission spectroscopic techniques. Further, their nonlinear optical properties were evaluated by Z-scan technique using Nd:YAG laser. These polymers showed strong optical limiting behavior with two-photon absorption (2PA) coefficients of the order of 10−10 m/W, which are comparable to that of good optical limiting materials reported in the literature. Also, it has been observed that the optical nonlinearity enhanced with the increase in donor–acceptor strength of the polymer backbone.

  • Synthesis, anticonvulsant and anti-inflammatory studies of new 1,4-dihydropyridin-4-yl-phenoxyacetohydrazones
    Shrikanth Ulloora, Ramakrishna Shabaraya, Rajesh Ranganathan, and Airody Vasudeva Adhikari

    European Journal of Medicinal Chemistry, ISSN: 02235234, eISSN: 17683254, Pages: 341-349, Published: 2013 Elsevier BV
    The present work involves design and synthesis of new substituted 1,4-dihydropyridin-4-yl-phenoxyacetohydrazones (4a-s, 5a-h), starting from 4-hydroxybenzaldehyde. The final compounds were screened for their in vivo anticonvulsant activity by MES, scPTZ and 6 Hz methods, while their anti-inflammatory screening was performed by Carrageenan induced Paw Edema method. The results indicated that compounds carrying electron donating groups are anticonvulsant active, while most of the tested compounds exhibited significant anti-inflammatory activity. Compounds 4k, l, 4p-s, and 5c showed rapid anti-inflammatory activity within 30 min and appeared as lead compounds. Further, Neurotoxicity study revealed that all the tested compounds are non-toxic up to 300 mg/kg doses. Selected compounds were also subjected to analgesic screening following Tail immersion method and they exhibited good activity.

  • Recent developments in photoalignment technology: Alignment properties of a thiophene based bis-hydrazone derivative
    Proceedings of the International Display Workshops, ISSN: 18832490, Pages: 97-98, Published: 2012

  • New optical limiting polymeric materials with different π-electron conjugation bridge structures: Synthesis and characterization
    K.A. Vishnumurthy, M.S. Sunitha, and A. Vasudeva Adhikari

    European Polymer Journal, ISSN: 00143057, Pages: 1575-1585, Published: September 2012 Elsevier BV
    Abstract In this communication we describe the design and synthesis of five new conjugated polymers (P1–P5) with various π-electron conjugation bridges. Their structures were established by FTIR, 1H NMR spectroscopy, elemental analysis. The molecular weights of the polymers were estimated by gel permeation chromatographic technique. Further, their electrochemical, linear and nonlinear optical properties were investigated. The electrochemical band gaps of P1–P5 were found to be 1.72–2.35 eV. Their third-order nonlinear optical activities were studied by open aperture Z-scan technique, using a Q-switched, frequency doubled Nd:YAG laser producing 7 nano second laser pulses at 532 nm. Z-scan results reveal that the polymers exhibit self-defocusing nonlinearity and their operating mechanism involves reverse saturable absorption. The polymers showed strong optical limiting behavior due to effective two-photon absorption (2PA) with 2PA coefficients of the order of 10−11 m/W, which is comparable to that of good optical limiting materials in the literature.

  • Large third-order nonlinearity of new π-conjugated donor-acceptor polymers with substituted thiophene and 1,3,4-oxadiazole moieties
    M. S. Sunitha, A. V. Adhikari, K. A. Vishnumurthy, K. Safakath, and R. Philip

    International Journal of Polymeric Materials and Polymeric Biomaterials, ISSN: 00914037, eISSN: 1563535X, Pages: 483-504, Published: 15 June 2012 Informa UK Limited
    We present the synthesis of two newly designed, thiophene-based conjugated polymers (P1 and P2) carrying 1,3,4-oxadiazole, 3,4-dinaphthyloxy thiophene, and 3,4-dialkoxy thiophene moieties as potential NLO active materials. Their NLO properties have been investigated both by the Z-scan and degenerate four-wave mixing (DFWM) techniques using 532 nm, 7 nanosecond laser pulses. The measured β and χ(3) values for the polymers are found to be in the range of 10−11 m/W and 10−11 esu, respectively. The results indicate that they exhibit good optical-limiting behavior and are promising materials for nonlinear optical applications due to effective two-photon absorption (TPA).

  • Electrochemical and nonlinear optical studies of new D-A type π-conjugated polymers carrying 3,4-benzyloxythiophene, oxadiazole, and 3,4-alkoxythiophene systems
    M. S. Sunitha, Airody Vasudeva Adhikari, K. A. Vishnumurthy, N. Smijesh, and Reji Philip

    Chemistry Letters, ISSN: 03667022, eISSN: 13480715, Pages: 234-236, Published: 2012 The Chemical Society of Japan

  • Synthesis and mesomorphism of new 2-methoxy-3-cyanopyridine mesogens
    T. N. Ahipa and Airody Vasudeva Adhikari

    Proceedings of SPIE - The International Society for Optical Engineering, ISSN: 0277786X, Volume: 8279, Published: 2012 SPIE
    In the present paper, we describe the synthesis and characterization of six new bent -shaped molecules carrying the 2-methoxy-3-cyanopyridine as a core possessing an outer phenylene unit at the lengthening arm with different alkoxy chain lengths (C-10 and C-12). Mesomorphic behaviors of the new compounds were investigated using optical polarizing microscope and DSC studies. Also, the effect of structural variables on mesogenic properties was studied. All the new cyanopyridine derivatives showed good liquid crystalline properties and exhibit smectic phase.

  • New diphenylamine-based donor-acceptor-type conjugated polymers as potential photonic materials
    K.A. Vishnumurthy, M.S. Sunitha, Reji Philip, and Airody Vasudeva Adhikari

    Reactive and Functional Polymers, ISSN: 13815148, Pages: 1119-1128, Published: December 2011 Elsevier BV
    Abstract A new series of donor–acceptor-type conjugated polymers ( P1 and P2 ) carrying a diphenyl amine moiety were synthesized via Wittig condensation technique. The polymers structures were well established by FT-IR, 1 H NMR, elemental analysis and gel permeation chromatographic techniques. They exhibited good thermal stability with an onset decomposition temperature of approximately 325 °C under nitrogen atmosphere. The optical and electrochemical properties of the polymers were studied by UV–vis, fluorescence emission spectroscopy and cyclic voltammetry. They exhibited good fluorescence in dilute solutions and showed solvatochromic behavior in various polar solvents. The electrochemical studies revealed that the polymers possess low-lying LUMO energy levels that ranging from −3.47 to −3.73 eV and high-lying HOMO energy levels that ranging from −5.57 to −5.81 eV. The thirdorder nonlinear optical properties of the polymers were investigated using the Z-scan technique. The effective two-photon absorption (TPA) coefficients ( β ) of the polymers were found to be 0.645 × 10 −10 and 0.212 × 10 −10  m/W.

  • Nonlinear optical characterization of new thiophene-based conjugated polymers for photonic switching applications
    Pramod Kumar Hegde, A. Vasudeva Adhikari, M. G. Manjunatha, C. S. Suchand Sandeep, and Reji Philip

    Advances in Polymer Technology, ISSN: 07306679, eISSN: 10982329, Pages: 312-321, Published: December 2011 Wiley
    This research article describes a technique to synthesize new donor−acceptor-type conjugated polymers carrying 1,3,4-oxadiazolyl-naphthalene and 3,4-(ethylenedioxy/diphenyl)-thiophene moieties (P1 and P2) starting from 2,2′-sulfanediyldiacetic acid and diethyl ethanedioate through multistep reactions. The newly synthesized intermediates and the final polymers have been characterized by different spectroscopic techniques followed by elemental analysis. Their optical and electrochemical properties have been investigated by UV–visible, fluorescence spectroscopy, and cyclic voltammetric studies, respectively. Furthermore, the nonlinear optical transmission properties of these polymers have been investigated by the open aperture z-scan technique. The new polymers P1 and P2 have well-defined structures, good thermal stability, and band gaps of 1.98 and 1.88 eV, respectively. They emit bluish-green fluorescence both in solution and in film state. Interestingly, these polymers show saturable absorption behavior. The results of nonlinear optical studies reveal that they are potential candidates for photonic switching device applications. © 2011 Wiley Periodicals, Inc. Adv Polym Techn 30: 312–321, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.20227

  • Nonlinear optical properties of a newly synthesized thiophene based conjugated polymer
    M. S. Sunitha, A. V. Adhikari, K. A. Vishnumurthy, Reji Philip, P. Predeep, Mrinal Thakur, and M. K. Ravi Varma

    AIP Conference Proceedings, ISSN: 0094243X, eISSN: 15517616, Volume: 1391, Pages: 703-705, Published: 2011 AIP
    We have synthesized a new donor‐acceptor (D‐A) conjugated polymer containing 3,4‐aralkyloxy and alkoxy substituted thiophene and 1,3,4‐oxadiazole as donor and acceptor moieties respectively, through precursor polyhydrazide route. The required polyhydrazide was synthesized from 3,4‐dihydroxythiophene diester through multistep reaction. The new polymer was characterized by using FTIR, 1H NMR spectroscopy, followed by Elemental analysis. The average molecular weight of the polymer was determined by Gel Permeation Chromatography. The band gap of the polymer was calculated by using UV‐visible and cyclic voltametry. Further, its NLO properties in THF solution were investigated both by the Z‐scan and degenerate four‐wave mixing (DFWM) techniques using 532 nm, 7 nanosecond laser pulses. The results indicate that they exhibit good optical limiting behavior due to effective two‐photon absorption (TPA). Values of the effective TPA coefficient (β), third‐order non‐linear optical susceptibility (χ(3)) and figure of me...

  • Synthesis and characterization of a new conjugated polymer bearing pyrazole and thiophene moieties as potent NLO material
    K. A. Vishnumurthy, A. Vasudeva Adhikari, M. S. Sunitha, Reji Philip, P. Predeep, Mrinal Thakur, and M. K. Ravi Varma

    AIP Conference Proceedings, ISSN: 0094243X, eISSN: 15517616, Volume: 1391, Pages: 652-654, Published: 2011 AIP
    In this communication we describe the design and synthesis of a new conjugated polymer (P) carrying 3,4‐dialkoxythiophene, 1,3,4 oxadiazole and pyrazole units, from its monomers through condensation polymerization method. The structure of newly synthesized polymer was established by FT‐IR, 1H NMR, elemental analysis and gel permeation chromatographic techniques. Further, its electrochemical, linear and nonlinear optical properties of the polymer have been investigated. The optical and electrochemical band gap was found to be 2.39 eV. Z‐scan results reveal that the polymer exhibits strong optical limiting behavior due to effective three‐photon absorption (3PA). The value of 3PA coefficient was found to be 1.1×10−20 m3/W2, which is comparable to that of good optical limiting materials. The fluorescence quantum yield of the polymer in solution was determined using quinine sulfate as standard and it was found to be 42%.

  • Design, synthesis and docking studies of new quinoline-3-carbohydrazide derivatives as antitubercular agents
    K.D. Thomas, Airody Vasudeva Adhikari, Sandeep Telkar, Imran H. Chowdhury, Riaz Mahmood, Nishith K. Pal, Guru Row, and E. Sumesh

    European Journal of Medicinal Chemistry, ISSN: 02235234, eISSN: 17683254, Pages: 5283-5292, Published: November 2011 Elsevier BV
    Three new series of 4-hydroxy-8-trifluoromethyl-quinoline derivatives were synthesized through multi step reactions. All the newly synthesized compounds were characterized by spectral and elemental analyses. The structure of 5j was evidenced by X-ray crystallographic study. The newly synthesized title compounds were evaluated for their antimicrobial activities including antimycobacterial activity. Amongst the tested compounds, 5b, 5e, 5h, 5j, 6c and 7c displayed promising antimicrobial activity. The mode of action of these active compounds was carried out by docking of receptor enoyl-ACP reductase with newly synthesized candidate ligands, 5b, 5e, 5h, 5j and 6c.

  • Design, synthesis and docking studies of quinoline-oxazolidinone hybrid molecules and their antitubercular properties
    K.D. Thomas, Airody Vasudeva Adhikari, Imran H. Chowdhury, T. Sandeep, R. Mahmood, B. Bhattacharya, and E. Sumesh

    European Journal of Medicinal Chemistry, ISSN: 02235234, eISSN: 17683254, Pages: 4834-4845, Published: October 2011 Elsevier BV
    New series of quinoline-oxazolidinone hybrid molecules were synthesized based on the preliminary docking studies. All the newly synthesized compounds were characterized by spectral analyses. The newly synthesized compounds were screened for their antimycobacterial properties based on the promising preliminary antibacterial screening results. Amongst tested compounds, compounds 8a, 8j and 13a were active at 0.65 μg/mL against Mycobacterium tuberculosis H(37)Rv strain. The mode of action of these active compounds was carried out by docking of receptor enoyl-ACP reductase with newly synthesized candidate ligands 8a, 8j and 13a. These compounds exhibited well established bonds with one or more amino acids in the receptor active pocket. From the docking studies, compound 8j was considered to be the best inhibitor.

  • Synthesis, electrochemical and optical studies of new cyanopyridine based conjugated polymers as potential fluorescent materials
    K.A. Vishnumurthy, M.S. Sunitha, K. Safakath, Reji Philip, and Airody Vasudeva Adhikari

    polymer, ISSN: 00323861, Pages: 4174-4183, Published: 1 September 2011 Elsevier BV
    Abstract In this communication we describe the design and synthesis of four new conjugated polymers (P1–P4) carrying cyanopyridine in their backbone via Wittig condensation technique. Their structures were well established by FTIR, 1H NMR, elemental analysis and gel permeation chromatographic techniques. They exhibited good thermal stability with the onset decomposition temperature around 300–350 °C in nitrogen atmosphere. Further, their electrochemical, linear and third-order non-linear optical properties have been investigated. The polymers showed low electrochemical band gaps in the range of 1.77–1.99 eV and displayed very good fluorescence emission property in various polar solvents. The fluorescence quantum yields of polymers P1–P4 in tetrahydrofuran (THF) were found to be 35, 42, 38 and 34%, respectively. The effective two-photon absorption coefficients (β) for the polymers were determined by Z-Scan technique and were found to be 1.34 × 10−11, 1.24 × 10−11, 3.04 × 10−11 and 1.85 × 10−11 m/W for polymers P1–P4, respectively.

  • Design and synthesis of a new thiophene based donor-acceptor type conjugated polymer with large third order nonlinear optical activity
    K.A. Vishnumurthy, A. Vasudeva Adhikari, M.S. Sunitha, K.A. Ann Mary, and Reji Philip

    Synthetic Metals, ISSN: 03796779, Volume: 161, Issue: 15-16, Pages: 1699-1706, Published: August 2011 Elsevier BV
    Abstract In this communication we describe the design and synthesis of a new conjugated polymer (P) carrying 3,4-dialkoxythiophene, 1,3,4-oxadiazole and thienylene-vinylene units, from its monomers using Wittig condensation method. The structure of newly synthesized polymer was confirmed by FT-IR, 1H NMR, UV–vis spectral, elemental analysis and gel permeation chromatographic techniques. The polymer exhibited good thermal stability with the onset decomposition temperature around 320 °C in nitrogen atmosphere. Further, its electrochemical, linear and nonlinear optical properties have been investigated. The optical and electrochemical band gap was found to be 2.21 eV. Its third-order nonlinear optical property was investigated by Z-scan and DFWM techniques, using a Q-switched, frequency doubled Nd:YAG laser producing 7 ns laser pulses at 532 nm. Z-scan results reveal that the polymer exhibits self-defocusing nonlinearity. The operating mechanism involves reverse saturable absorption. The polymer shows strong optical limiting behavior due to effective two-photon absorption (2PA). The value of 2PA coefficient was found to be 3.0 × 10−11 mW, which is comparable to that of good optical limiting materials. The fluorescence quantum yield of the polymer in solution was determined using quinine sulfate as standard and it was found to be 35%.

  • New quinolin-4-yl-1,2,3-triazoles carrying amides, sulphonamides and amidopiperazines as potential antitubercular agents
    K.D. Thomas, Airody Vasudeva Adhikari, Imran H. Chowdhury, E. Sumesh, and Nishith K. Pal

    European Journal of Medicinal Chemistry, ISSN: 02235234, eISSN: 17683254, Pages: 2503-2512, Published: June 2011 Elsevier BV
    Three new series of quinoline-4-yl-1,2,3-triazoles carrying amides, sulphonamides and amidopiperazines were synthesized through multi-step reactions. The required intermediate, [1-(6-methoxy-2-methylquinolin-4-yl)-1H-1,2,3-triazol-4-yl]methanol (2) was prepared by treating 4-azido-6-methoxy-2-methylquinoline (1) with propargyl alcohol. Three different series of compounds were synthesized from this intermediate. All the newly synthesized compounds were characterized by spectral and elemental analyses. The structure of 2 was confirmed by X-ray crystallographic study. Further, the title compounds were evaluated for their in vitro anti-bacterial activity against five different bacterial strains and antimycobacterial activity against Mycobacterium tuberculosis H37Rv, Mycobacterium smegmatis (ATCC 19420) and Mycobacterium fortuitum (ATCC 19542). Title compounds, 6a, 6d, 6i, 6j, 7e, 10a and 10i were found to be active against Mycobacterium tuberculosis H37Rv strain and could be lead molecules of interest.

  • Synthesis and pharmacological studies on some novel imidazo thiazoles
    Der Pharma Chemica, eISSN: 0975413X, Pages: 277-282, Published: 2011

  • Novel poly(3,4-dialkoxythiophene)s carrying 1,3,4-oxadiazolyl-biphenyl moieties: Synthesis and nonlinear optical studies
    Pramod Kumar Hegde, A Vasudeva Adhikari, Megur G Manjunatha, CS Suchand Sandeep, and Reji Philip

    Polymer International, ISSN: 09598103, eISSN: 10970126, Pages: 112-118, Published: January 2011 Wiley
    Two new donor–acceptor types of polymer, poly{2-(biphenyl-4-yl)-5-[3,4-dialkoxy-5-(1,3,4-oxadiazol-2-yl)thiophen-2-yl]-1,3,4-oxadiazole}s, were synthesized starting from 2,2′-sulfanediyldiacetic acid and diethyl ethanedioate through multi-step reactions. The polymerization was carried out via the polyhydrazide precursor route. The optical and charge-transporting properties of the polymers were investigated using UV-visible and fluorescence emission spectroscopic and cyclic voltammetric studies. The polymers showed bluish-green fluorescence in solutions. The electrochemical band gaps of the polymers were determined to be 2.16 and 2.22 eV. The nonlinear optical properties of the polymers were investigated at 532 nm using the single-beam Z-scan technique with nanosecond laser pulses. The polymers showed strong optical limiting behaviour due to effective three-photon absorption. The values of the three-photon absorption coefficients for the polymers were found to be 9 × 10−24 and 17 × 10−24 m3 W−2, which are comparable to those of good optical limiting materials. Copyright © 2010 Society of Chemical Industry

  • A new nonlinear optically active donor-acceptor-type conjugated polymer: Synthesis and electrochemical and optical characterization
    M. G. Manjunatha, A. V. Adhikari, P. K. Hegde, C. S. Suchand Sandeep, and Reji Philip

    Journal of Electronic Materials, ISSN: 03615235, Pages: 2711-2719, Published: December 2010 Springer Science and Business Media LLC
    A new donor–acceptor-type poly[3-{5-[3,4-didodecyloxy-5-(1,3,4-oxadiazol- 2-yl)thiophen-2-yl]-1,3,4-oxadiazol-2-yl}-9-dodecyl-9H-carbazole] (P) has been synthesized through multistep reactions. The new polymer P exhibited good thermal stability and film-forming behavior. The electrochemical band gap is estimated to be 2.15 eV. The polymer emits intense green fluorescence in the solid state. Third-order nonlinear optical (NLO) studies showed that the strong absorptive nonlinearity observed for the polymer is of the optical limiting type, which is due to an “effective” three-photon absorption (3PA) process. This 3PA process can have potential applications in photonic devices. The studies revealed that the new polymer P is a promising material for development of efficient optoelectronic devices.

  • Photoalignment of nematic liquid crystal by thin films of bishydrazones derived from 3,4 dipropyloxythiophene
    IDW'10 - Proceedings of the 17th International Display Workshops, Pages: 77-80, Published: 2010

  • Design and Synthesis of New Amides and Thioamides Derived from 3,4-Ethylenedioxythiophene as Potential Anticonvulsants
    Ravi Kulandasamy, Airody Vasudeva Adhikari, and James P. Stables

    Bulletin of the Korean Chemical Society, ISSN: 02532964, eISSN: 12295949, Pages: 3318-3326, Published: 20 November 2010 Korean Chemical Society
    Five new series of 3,4-ethylenedioxythiophene derivatives carrying important pharamacophores, viz., amide, ester, ether and active secondary aryl moieties have been designed and synthesized through multistep reactions starting from thiodiglycolic ester and diethyl oxalate. They have been characterized by elemental and spectral data. All the target compounds have been screened for their anticonvulsant activity at three different models viz. maximal electroshock (MES), subcutaneous metrazole (scMET), and 6 Hz screen and evaluated for their neurotoxicity in rotorod model. Compound 6a emerged as lead with no neurotoxicity. All the five series of compounds are safe in the toxicity studies at the maximum dose of 300 mg/kg of body weight. Amongst the tested compounds, the ester pharmacophore with thioamide fragment has showed better activity than the other analogs.

  • Nonlinear optical studies on new conjugated poly{2,2 l-(3,4- dialkoxythiophene-2,5-diyl) bis[5-(2-thienyl)-1,3,4-oxadiazole]}s
    Pramod Kumar Hegde, A. Vasudeva Adhikari, M. G. Manjunatha, C. S. Suchand Sandeep, and Reji Philip

    Journal of Applied Polymer Science, ISSN: 00218995, eISSN: 10974628, Volume: 117, Pages: 2641-2650, Published: 5 September 2010 Wiley
    Three new donor–acceptor type poly{2,2l-(3,4- dialkoxythiophene-2,5-diyl)bis[5-(2-thienyl)-1,3,4-oxadiazole]}s (P1, P2, and P3) were synthesized starting from thiodiglycolic acid and diethyl oxalate through multistep reactions. The polymerization was carried out using chemical polymerization technique. The optical and charge-transporting properties of the polymers were investigated by UV-visible, fluorescence emission spectroscopic and cyclic voltammetric studies. The polymers showed bluish-green fluorescence in solutions. The electrochemical band gaps were determined to be 2.03, 2.09, and 2.17 eV for P1, P2, and P3, respectively. The nonlinear optical properties of new polymers were investigated at 532 nm using single beam Z-scan and degenerate four-wave mixing (DFWM) techniques with nanosecond laser pulses. The polymers exhibited strong optical limiting behavior due to “effective” three-photon absorption. Values of the effective three-photon absorption (3PA) coefficients, third-order nonlinear susceptibilities (χ(3)), and figures (F) of merit were calculated. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

  • Design, synthesis and antimicrobial activities of some new quinoline derivatives carrying 1,2,3-triazole moiety
    K.D. Thomas, Airody Vasudeva Adhikari, and N. Suchetha Shetty

    European Journal of Medicinal Chemistry, ISSN: 02235234, eISSN: 17683254, Pages: 3803-3810, Published: September 2010 Elsevier BV
    A new series of [1-(6-methoxy-2-methylquinolin-4-yl)-1H-1,2,3-triazol-4-yl] methanamine derivatives were synthesized starting from 4-methoxyaniline through multi-step reactions. The title compounds 5a-y were prepared by treating the azide intermediate 4 with propargyl bromide and different alkyl/heterocyclic amines in a sequential three component synthesis. All the new compounds were characterized by spectral and elemental analyses. The newly synthesized final compounds were evaluated for their in vitro antibacterial and antifungal activities against pathogenic strains. The preliminary screening results indicated that most of the compounds demonstrated moderate to very good antibacterial and antifungal activities, comparable to the first-line drugs.

  • A new donor-acceptor type conjugative poly{2-[4-(1-cyanoethenyl)phenyl]-3- (3,4-didodecyloxythiophen-2-yl)prop-2-enenitrile}: Synthesis and NLO studies
    Pramod Kumar Hegde, A. Vasudeva Adhikari, M.G. Manjunatha, C.S. Suchand Sandeep, and Reji Philip

    Synthetic Metals, ISSN: 03796779, Volume: 160, Issue: 15-16, Pages: 1712-1717, Published: 2010 Elsevier BV
    Abstract This research article describes a technique to synthesize a new donor–acceptor type conjugated polymer carrying cyanophenylenevinylene and 3,4-didodecyloxy thiophene moieties, as an effective optical limiting material. It also includes the evaluation of its linear and nonlinear optical properties and electrochemical studies. The new polymer, viz., poly{2-[4-(1-cyanoethenyl)phenyl]-3-(3,4-didodecyloxythiophen-2-yl)prop-2-enenitrile} ( P1 ) has been synthesized starting from 2,2′-sulfanediyldiacetic acid and diethyl ethanedioate through multistep reactions. In the final step, the polymerization was brought about by Knovenagel condensation. The newly synthesized intermediate, monomer and the polymer ( P1 ) have been characterized by different spectroscopic techniques followed by elemental analysis. Its optical and electrochemical properties are investigated by UV–vis, fluorescence spectroscopy and cyclic voltammetric studies, respectively. The red colored polymer has a well defined structure, good thermal stability and a band gap of 1.78 eV. It emits green fluorescence both in solution and in film state. The third-order nonlinear optical property (NLO) of the polymer was studied by the Z-scan technique. The measurements were performed at 532 nm with 5 ns laser pulses using samples in solution form. An absorptive nonlinearity of the optical limiting type was found in this polymer, which is due to the combined action of saturable absorption and excited state absorption processes. These studies revealed that polymer P1 is a promising material for optical limiting applications.

  • New hydrazides and thiosemicarbazides derived from ethylenedioxythiophene as potential anticonvulsants
    Ravi Kulandasamy, Airody Vasudeva Adhikari, Ashok Taranalli, and Thimmaiah Venkataswamy

    Phosphorus, Sulfur and Silicon and the Related Elements, ISSN: 10426507, eISSN: 15635325, Volume: 185, Pages: 1358-1368, Published: July 2010 Informa UK Limited
    A series of ethyl 7-({2-[(substituted)carbonyl]hydrazino}carbonyl)-2,3-dihydrothieno [3,4-b][1,4]dioxine-5-carboxylates (5–13) and ethyl 7-{[({2-[(substituted)carbonyl]hydra-zino}carbonothioyl)amino]carbonyl}-2,3-dihydrothieno[3,4-b][1,4]dioxine-5-carboxy-lates (15–20) were synthesized in good yield by condensing ethyl-7-(chlorocarbonyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine-5-carboxylate (4) with suitable hydrazides. The newly synthesized compounds were characterized using FTIR, 1H NMR, 13C NMR, mass spectroscopy, and elemental analyses. The anticonvulsant activity of all the title compounds was investigated against maximal electroshock-induced seizures (MES) and pentylenetetrazole (PTZ)-induced convulsion models. None of the compounds showed toxicity at the maximum dose of 2000 mg/kg. Almost all the compounds showed protection in flexion and extension stage against induced convulsion. Among them, naphthyloxy-substituted derivatives exhibited very good response against induced seizures. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

  • Synthesis and characterization of a new NLO-active donor-acceptor-type conjugated polymer derived from 3,4-diphenylthiophene
    M. G. Manjunatha, Airody Vasudeva Adhikari, Pramod Kumar Hegde, C. S. Suchand Sandeep, and Reji Philip

    Journal of Polymer Research, ISSN: 10229760, Pages: 495-502, Published: July 2010 Springer Science and Business Media LLC
    A new donor–acceptor-type conjugated polymer (P1) carrying 3,4-diphenylthiophene, 2,5-dihexyloxybenzene, and 1,3,4-oxadiazole units was synthesized through multistep reactions. The polymer was prepared using a polyhydrazide precursor route. The polymer has a well-defined structure and exhibits good thermal stability, with a decomposition onset temperature in nitrogen of 300 °C. Cyclic voltammetry experiments revealed that the polymer has low-lying LUMO (−3.68 eV) and high-lying HOMO (−5.78 eV) energy levels. The electrochemical band gap was found to be 2.10 eV. The UV-visible absorption spectrum of the polymer presented a maximum at 373 nm, and it displayed bluish-green fluorescence in dilute chloroform solution. The nonlinear optical properties of the new polymer were investigated at 532 nm using the Z-scan technique with nanosecond laser pulses. The polymer exhibited strong optical limiting behavior due to excited state absorption, which was phenomenologically similar to a three-photon absorption (3PA) process. The 3PA coefficient γ was found to be 7 × 10−22 m3/W2. The studies show that the new polymer (P1) is a promising material for developing efficient photonic devices.

  • 3,3′-Benzene-1,4-diylbis[1-(substituted)phenylprop-2-en-1-one] derivatives: A new class of materials for third-order nonlinear optical applications
    P. Poornesh, K. Ravi, G. Umesh, P.K. Hegde, M.G. Manjunatha, K.B. Manjunatha, and A.V. Adhikari

    Optics Communications, ISSN: 00304018, Volume: 283, Pages: 1519-1527, Published: 1 April 2010 Elsevier BV
    We have investigated the third-order nonlinear optical parameters of Bischalcones embedded in DMF solution and in solid PMMA matrix, by Z-scan technique using nanosecond laser pulse trains at 532 nm. Z-scan results reveal that the Bischalcones exhibits negative nonlinear refractive index as high as 10�11 esu. The molecular two-photon absorption cross-section r0 2 of Bischalcones were of the order 10�46 cm4 s/photon, which is nearly two orders of magnitude larger than that of Rhodamine 6G which is 10�48 – 10�50 cm4 s/photon. We found that, the two-photon absorption (TPA) is the dominating nonlinear process leading to nonlinear absorption in both the cases in solution and as well as in solid medium. Based on TPA process, the Bischalcones exhibit good optical power limiting of nanosecond laser pulses at the input wavelength. The nonlinear optical parameters found to increase on enhancing the strength of the electron donor groups indicating the dependence and importance of electron donor/ acceptor units on third-order nonlinear optical susceptibility v(3)

  • New 1,3-oxazolo[4,5-c]quinoline derivatives: Synthesis and evaluation of antibacterial and antituberculosis properties
    Sumesh Eswaran, Airody Vasudeva Adhikari, and R. Ajay Kumar

    European Journal of Medicinal Chemistry, ISSN: 02235234, eISSN: 17683254, Pages: 957-966, Published: March 2010 Elsevier BV
    A new class of fused oxazoloquinoline derivatives was synthesized starting from 2-bromo-1-phenylethanones 1a-b through multi-step reactions. The newly synthesized compounds were evaluated for their in vitro antibacterial against Escherichia coli (ATTC-25922), Staphylococcus aureus (ATTC-25923), Pseudomonas aeruginosa (ATCC-27853) and Klebsiella pneumoniae (recultured) and antituberculosis activity against Mycobacterium tuberculosis H37Rv (ATCC 27294). Preliminary results indicated that most of the compounds demonstrated very good antibacterial and antituberculosis activities which are comparable with the first line drugs. Compounds 6a, 6c, 6g, 6j, 6k and 6n emerged as the lead antitubercular agents with MIC, 1 microg/mL and 99% bacterial inhibition while eight compounds, viz., 5a, 15k, 6a, 6c, 6g, 6j, 6k and 6n were found to be more potent than INH (MIC: 1.5 microg/mL) with MIC 1 microg/mL.

  • Design and synthesis of some new quinoline-3-carbohydrazone derivatives as potential antimycobacterial agents
    Sumesh Eswaran, Airody Vasudeva Adhikari, Nishith K. Pal, and Imran H. Chowdhury

    Bioorganic and Medicinal Chemistry Letters, ISSN: 0960894X, Pages: 1040-1044, Published: 1 February 2010 Elsevier BV
    A series of 26 new quinoline derivatives carrying active pharmacophores has been synthesized and evaluated for their in vitro antituberculosis activity against Mycobacterium tuberculosis H37Rv (MTB), Mycobacterium smegmatis (MC(2)), and Mycobacterium fortuitum following the broth micro dilution assay method. Compounds 13e, 13i, 13k, 14a, 14c, 14i, and 14k exhibited significant minimum inhibition concentrations, when compared with first line drugs isoniazid (INH) and rifampicin (RIF) and could be ideally suited for further modifications to obtain more efficacious compounds in the fight against multi-drug resistant tuberculosis.

  • Nonlinear optical and optical power limiting studies on a new thiophene-based conjugated polymer in solution and solid PMMA matrix
    P. Poornesh, Pramod K. Hegde, G. Umesh, M.G. Manjunatha, K.B. Manjunatha, and A.V. Adhikari

    Optics and Laser Technology, ISSN: 00303992, Pages: 230-236, Published: February 2010 Elsevier BV
    An experimental investigation of the third-order nonlinear optical properties of new poly{2-{5-[3,4-ditetradecyloxy-5-(1,3,4-oxadiazol-2-yl)thiophen-2-yl]-1,3,4-oxadiazol-2-yl}pyridine} (P) in tetrahydrofuran (THF) solution and in solid poly(methylmethacrylate) (PMMA) matrix, by Z-scan technique is reported. The Z-scan traces reveal that the composite films exhibit large negative nonlinear refractive index of the order 10�10 esu. The excited-state absorption cross-section was found to be larger than the ground-state absorption indicating that the operating nonlinear process is reverse saturable absorption (RSA). The new polymer P exhibits good optical power limiting properties in the nanosecond regime in solution and as well in solid PMMA matrix.

  • A novel narrow band gap red light-emitting cyanovinylene polymer derived from 3,4-dialkoxy thiophene for optoelectronic applications
    M. G. Manjunatha, A. V. Adhikari, and P. K. Hegde

    Journal of Materials Science: Materials in Electronics, ISSN: 09574522, eISSN: 1573482X, Pages: 751-757, Published: August 2010 Springer Science and Business Media LLC
    A novel donor–acceptor type narrow band gap cyanovinylene poly{3,3′-(3,4-ditetradecyloxythiene-2,5-diyl)bis[2-(thiophen-2-yl)prop-2-enenitrile]} has been designed and synthesized through multistep reactions. All the newly synthesized compounds were characterized by using FTIR and 1H NMR spectroscopy followed by elemental analyses. The polymer P is found to be thermally stable up to 300 °C under nitrogen atmosphere. The optical and charge-transporting properties of the polymer were investigated by UV–visible, fluorescence emission spectroscopic and cyclic voltammetric studies. The monomer (M) emits intense green-light in solution state and the polymer (P) exhibited intense red-fluorescence both in solution and solid state. The fluorescence quantum yield of the polymer is determined to be 43%. Cyclic voltammetric studies reveal that the polymer possesses good charge carrying property. The electrochemical band-gap is estimated to be 1.8 eV. The studies reveal that the new cyanovinylene polymer P is a promising material for the development of efficient optoelectronic devices.

  • Electrochemical and optical properties of a new donor-acceptor type conjugated polymer derived from 3,4-didodecyloxythiophene
    PRAMOD KUMAR HEGDE, A VASUDEVA ADHIKARI, and M G MANJUNATHA

    Bulletin of Materials Science, ISSN: 02504707, Pages: 677-682, Published: December 2010 Springer Science and Business Media LLC
    In this communication, we report the synthesis and characterization of a new donor–acceptor type conjugated polymer carrying alternate 3,4-didodecyloxythiophene and (1,3,4-oxadiazol-yl)pyridine moieties and evaluation of its optical and electrochemical properties. The polymer was synthesized through precursor polyhydrazide route. It has well defined structure, stability and it shows good solubility in common organic solvents. Optical and electrochemical properties were studied by UV-visible, fluorescence spectroscopy and cyclic voltammetric studies, respectively. It displays bluish-green fluorescence both in solution and in film state. Cyclic voltammetric studies showed that the polymer P1 possesses a HOMO energy level of −6·01 and LUMO energy level of −3·34 eV. The preliminary studies clearly reveal that the new polymer can have potential application in the fabrication of light emitting diodes. The studies on its device application are in progress.

  • Optical and electrochemical properties of a new donor-acceptor type conjugated polymer derived from thiophene, carbazole and 1,3,4-oxadiazole units
    M.G. Manjunatha, Airody Vasudeva Adhikari, and Pramod Kumar Hegde

    Materials Science Forum, ISSN: 02555476, eISSN: 16629752, Volume: 657, Pages: 46-55, Published: 2010 Trans Tech Publications, Ltd.
    A new donor-acceptor type poly[3-{5-[3,4-didecyloxy-5-(1,3,4-oxadiazol-2-yl)thiophen-2-yl]-1,3,4-oxadiazol-2-yl}-9-dodecyl-9H-carbazole] (P) has been synthesized starting from thiodiglycolic acid and 9H-carbazole through multistep reactions. The polymer has been synthesized through precursor polyhydrazide route. The weight average molecular weight of the polymer was found to be 7210. The polymer exhibited intense green fluorescence in solid sate. Cyclic voltammetric experiments showed that the polymer has low-lying LUMO (-3.55 eV) and high lying HOMO (-5.77 eV) energy levels due to the presence of alternate donor and acceptor units. The optical and electrochemical studies reveal that the new polymer (P) is a promising material for the development of polymer light emitting diodes (PLEDs).

  • Nonlinear optical studies on a new poly{2-(biphenyl-4-yl)-5-[3,4- didecyloxy-5-(1,3,4-oxadiazol-2-yl)thiophen-2-yl]-1,3,4-oxadiazole}
    Pramod Kumar Hegde, Airody Vasudeva Adhikari, M.G. Manjunatha, C.S. Suchand Sandeep, and Philip Reji

    Materials Science Forum, ISSN: 02555476, eISSN: 16629752, Volume: 657, Pages: 56-61, Published: 2010 Trans Tech Publications, Ltd.
    Measurements of nonlinear optical properties of a newly synthesized thiophene based polymer are reported. The nonlinear transmission measurements were performed on the polymer dissolved in N,N-dimethylformamide by employing the single beam Z-scan technique using a Q-switched laser output at 532-nm. The polymer shows strong optical limiting behavior, where the transmittance decreases when the pump fluence is increased. It was found that an effective three-photon absorption (3PA) model at the excitation wavelength gives the best fit to the obtained experimental data. The value of the 3PA coefficient has been numerically calculated. This study clearly reveals the potential of new polymeric material has, for optical limiting applications.

  • New quinoline derivatives: Synthesis and investigation of antibacterial and antituberculosis properties
    Sumesh Eswaran, Airody Vasudeva Adhikari, Imran H. Chowdhury, Nishith K. Pal, and K.D. Thomas

    European Journal of Medicinal Chemistry, ISSN: 02235234, eISSN: 17683254, Pages: 3374-3383, Published: August 2010 Elsevier BV
    Four new series of quinoline derivatives were synthesized starting from 2-trifluoromethyl aniline through multi-step reactions. In the reaction sequence, substituted aniline was cyclized to 4-hydroxy quinoline 1, which was then transformed to 4-chloro-2,8-bis(trifluoromethyl)quinoline 2. The key scaffold 4-hydrazinyl-2,8-bis(trifluoromethyl)quinoline 3, obtained from the compound 2, was successfully converted to target quinoline derivatives, viz. hydrazones 4a-t, ureas 5a-e, thioureas 6a-c and pyrazoles 7a-d, in good yields. The newly synthesized title compounds were evaluated for their in vitro antibacterial activity against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella pneumoniae (recultured) and antituberculosis activity against Mycobacterium tuberculosis H(37)Rv and MDR-TB. Preliminary results indicated that most of the hydrazone derivatives demonstrated very good antibacterial and antituberculosis activities while other derivatives showed moderate activity.

  • Synthesis and antimicrobial activities of novel quinoline derivatives carrying 1,2,4-triazole moiety
    Sumesh Eswaran, Airody Vasudeva Adhikari, and N. Suchetha Shetty

    European Journal of Medicinal Chemistry, ISSN: 02235234, eISSN: 17683254, Pages: 4637-4647, Published: November 2009 Elsevier BV
    A new class of quinoline derivatives containing 1,2,4-triazole moiety were synthesized from derivatives of 4-hydroxy-8-(trifluoromethyl)quinoline-3-carbohydrazide 4 through multi-step reactions. The compound 4, on treatment with substituted Isothiocyanates yielded quinoline-thiosemicarbazides 5a-c, which were conveniently cyclized to (5-mercapto-4H-triazol-3-yl)-quinolin-4-ols 6a-c in basic medium. These intermediates were then transformed to their respective chloro derivatives 7a-c by treatment with phosphorus oxychloride, which on further reaction with different biologically active rare amines yielded the target compounds 8a-g, 9a-h and 10a-h in good yield. The ultimate step, involving nucleophilic substitution reaction was achieved by microwave-induced technique, which has reduced the reaction time drastically as well as improved the yield when compared to conventional heating. The newly synthesized final compounds were evaluated for their in vitro antibacterial and antifungal activities against four strains each. Preliminary results indicated that most of the compounds demonstrated very good antimicrobial activity, comparable to the first line standard drugs. The most effective compounds have exhibited activity at MIC of 6.25 microg/mL.

  • A new class of anticonvulsants possessing 6 Hz activity: 3,4-Dialkyloxy thiophene bishydrazones
    Ravi Kulandasamy, Airody Vasudeva Adhikari, and James P. Stables

    European Journal of Medicinal Chemistry, ISSN: 02235234, eISSN: 17683254, Pages: 4376-4384, Published: November 2009 Elsevier BV
    Thirty nine new 3,4-di(substituted)oxy-N(2),N(5)-bis(substituted)thiophene-2,5-dicarbohydrazides were synthesized starting from ethyl thiodiglycolate through multi-step reactions. In the synthetic sequence, 3,4-dihydroxythiophene-2,5-diester (1) was obtained by condensing the ethyl thiodiglycolate with diethyl oxalate. It was derivatized using different alkyl halides to give disubstituted thiophene esters (2-5), which were then converted to corresponding hydrazides (6-9) following usual methods. Finally, these hydrazides, on treatment with various substituted carbonyl compounds underwent smooth condensation to yield target hydrazones (10-13). The new compounds were characterized using FT-IR, (1)H NMR and (13)C NMR, mass spectral and elemental analyses. The anticonvulsant activity of the title compounds was established after intraperitoneal (ip) administration in three seizure models, which include maximal electroshock (MES), subcutaneous pentylenetetrazole (scPTZ) and 6 Hz screens and their neurotoxicity was also evaluated. Compound 11f has emerged as an active compound with no neurotoxicity in this series. Also, the structure-activity relationship of the tested compounds was discussed.

  • Optical characterization of a new Donor-acceptor type conjugated polymer derived from 3,4-diphenylthiophene
    M. G. Manjunatha, Airody Vasudeva Adhikari, Pramod Kumar Hegde, C. S. Suchand Sandeep, and Reji Philip

    Journal of Materials Science, ISSN: 00222461, eISSN: 15734803, Pages: 6069-6077, Published: November 2009 Springer Science and Business Media LLC
    A new donor–acceptor type poly{2-(3,4-didecyloxythiophen-2-yl)-5-[3,4-diphenyl-5-(1,3,4-oxadiazol-2-yl)thiophen-2-yl]-1,3,4-oxadiazole} (P1) has been designed and synthesized starting from thiodiglycolic acid, 1,2-diphenylethane-1,2-dione, and diethyl oxalate through multi-step reactions using precursor polyhydrazide route. The charge-transporting and linear optical property of the polymer has been investigated by cyclic voltammetric, UV–visible, and fluorescence emission spectroscopic studies. The UV–visible absorption spectrum of polymer in thin film form showed maxima at 420 nm. The polymer displayed bluish-green fluorescence both in solution and thin film form. The optical band gap is determined to be 2.27 eV. Third-order nonlinear optical property of the new polymer has been investigated at 532 nm using single beam Z-scan and degenerate four wave mixing (DFWM) techniques with nanosecond laser pulses. The absorptive nonlinearity observed for the polymer P1 is of optical limiting type, which arises due to an “effective” three-photon absorption (3PA) process. The third-order nonlinear optical susceptibility (χ(3)) of the polymer is found to be 0.831 × 10–12 esu. Both linear and nonlinear optical studies revealed that the new polymer (P1) is a promising material for applications in photonic devices.

  • Synthesis and anticonvulsant activity of some new bishydrazones derived from 3,4-dipropyloxythiophene
    Ravi Kulandasamy, Airody Vasudeva Adhikari, and James P. Stables

    European Journal of Medicinal Chemistry, ISSN: 02235234, eISSN: 17683254, Pages: 3672-3679, Published: September 2009 Elsevier BV
    A series of new 3,4-dipropyloxy-N(2),N(5)-bis(substituted)thiophene-2,5-dicarbohydrazides (4-30) were synthesized from ethyl thiodiglycolate and diethyloxalate through multistep reactions. Following Dieckmann-Komppa reaction, the required precursor 3,4-dihydroxythiophene-2,5-diester (1) was prepared. This was derivatized with propyl bromide and further converted to corresponding hydrazide (3), which was finally transformed to targeted hydrazones (4-30) by conventional methods. The newly synthesized compounds were characterized using FT-IR, (1)H and (13)C NMR, EI-MS and elemental analyses. The anticonvulsant activity of all the title compounds was investigated against maximal electroshock induced seizures (MES) and subcutaneous pentylenetetrazole (scMET) models and their neurotoxicity was also evaluated. Some of the selected compounds were subjected to 6 Hz test in order to evaluate their uncover activities. Compound 3,4-dipropyloxy-N(2),N(5)-bis[1-(2-thienyl)ethylidene]thiophene-2,5-dicarbohydrazide (15) has emerged as a lead in this series with less neurotoxicity.

  • Studies on third-order nonlinear optical properties and reverse saturable absorption in polythiophene/poly (methylmethacrylate) composites
    P. Poornesh, G. Umesh, P. K. Hegde, M. G. Manjunatha, K. B. Manjunatha, and A. V. Adhikari

    Applied Physics B: Lasers and Optics, ISSN: 09462171, Pages: 117-124, Published: September 2009 Springer Science and Business Media LLC
    We report here the studies on third-order nonlinear optical properties of two novel polythiophene composite films investigated using the Z-scan technique. The measurements were carried out using a Q-switched, frequency doubled Nd:YAG laser producing 7 nanosecond laser pulses at 532 nm. Z-scan results reveal that the composite films exhibit self-defocusing nonlinearity. The real and imaginary parts of the third-order nonlinear optical susceptibility were of the order 10−12 esu. The effective excited-state absorption cross section was found to be larger than the ground state absorption cross section, indicating that the operating nonlinear mechanism is reverse saturable absorption (RSA). The polythiophene composite films also exhibit good optical power limiting of the nanosecond laser pulses. The nonlinear optical parameters are found to increase on increasing the strength of the electron-donor group, indicating the dependence of χ(3) on the electron-donor/acceptor units of polythiophenes.

  • Synthesis of some biologically active 2,4'-bipyridine-5-carbonitriles carrying the 4-hydroxyphenylthio moiety
    T. Karabasanagouda, Vasudeva Adhikari, and G. Parameshwarappa

    Journal of the Serbian Chemical Society, ISSN: 03525139, Pages: 733-743, Published: 2009 National Library of Serbia
    A series of new 4-aryl-2'-[(4-hydroxyphenyl)thio]-6oxo-1,6-dihydro- 2,4'-bipyridine-5-carbonitriles (3a-k) and 6-amino-4aryl-2'-[(4-hydroxyphenyl) thio]-2,4'-bipyridine-5-carbonitriles (4a-h) were synthesized from 4-hydroxythiophenol (1). The reaction of 4-hydroxythiophenol with 4-acetyl-2-chloropyridine yielded 1-{2-[(4-hydroxyphenyl)thio]pyridin-4-yl}ethanone (2). Further treatment of 2 with ethyl cyanoacetate in the presence of ammonium acetate with various aromatic aldehydes furnished the compounds 3a-k. On the other hand, condensation of 2 with aromatic aldehydes in the presence of alcoholic malononitrile in ammonium acetate gave compounds 4a-h. The structures of the newly synthesized compounds were established on the basis of their elemental analysis, as well as their IR, 1H- and 13C-NMR and mass spectral data. All the title compounds were subjected to in vitro antibacterial testing against two strains and antifungal screening against two fungi. Some of the compounds showed promising activity.

  • N′-[4-(diethylamino)benzylidine]-3-{[8-(trifluoromethyl) quinolin-4-yl]thio}propano hydrazide) as an effective inhibitor of mild steel corrosion in acid media
    Saliyan V. Ramesh and Airody Vasudeva Adhikari

    Materials Chemistry and Physics, ISSN: 02540584, Volume: 115, Issue: 2-3, Pages: 618-627, Published: 15 June 2009 Elsevier BV
    Abstract N′-[4-(diethylamino)benzylidine]-3-{[8-(trifluoromethyl)quinolin-4-yl]thio}propano hydrazide (DEQTPH) was newly synthesized, characterized and tested as a corrosion inhibitor for mild steel in HCl (1 M, 2 M) and H2SO4 (0.5 M, 1 M) solutions using weight loss method, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization method. The corrosion inhibition efficiencies measured by all the above three techniques were in good agreement with each other. The mild steel samples were also analyzed by scanning electron microscopy (SEM). The results showed that DEQTPH is an excellent inhibitor for mild steel in acid media. The inhibition efficiency in different acid media was found to be in the order, 0.5 M H2SO4 > 1.0 M HCl > 2.0 M HCl > 1.0 M H2SO4. The inhibition was assumed to occur via adsorption of the inhibitor molecule on the metal surface. It acts as an anodic inhibitor. In the 30–60 °C temperature range, the DEQTPH adsorption follows Langmuir isotherm model. The protection efficiency increased with increasing inhibitor concentration in the range 0.2 × 10−4 to 10.5 × 10−4 M and slightly increased with increasing temperature. Thermodynamic characteristics were discussed. Chemisorption mechanism is proposed.

  • Synthesis and nonlinear optical characterization of new poly{2,2′-(3,4-didodecyloxythiophene-2,5-diyl)bis[5-(2-thienyl)-1,3,4-oxadiazole]}
    Pramod Kumar Hegde, A.V. Adhikari, M.G. Manjunatha, C.S. Suchand Sandeep, and Reji Philip

    Synthetic Metals, ISSN: 03796779, Volume: 159, Pages: 1099-1105, Published: June 2009 Elsevier BV
    Abstract A new donor–acceptor type poly{2,2′-(3,4-didodecyloxythiophene-2,5-diyl)bis[5-(2-thienyl)-1,3,4-oxadiazole]} (P) was synthesized starting from thiodiglycolic acid and diethyl oxalate through multistep reactions. The polymerization was carried out using chemical polymerization technique. The optical and charge-transporting property of the copolymer was investigated by UV–vis, fluorescence emission spectroscopic and cyclic voltammetric studies. The copolymer shows UV absorption maxima at 375 nm and displays bluish-green fluorescence in DMF solution. Its electrochemical band gap was determined to be 2.07 eV. The nonlinear optical (NLO) properties of the copolymer was investigated at 532 nm using single beam Z-scan and degenerate four-wave mixing (DFWM) techniques with nanosecond laser pulses. The copolymer exhibits strong optical limiting behavior due to effective three-photon absorption (3PA). Values of the effective 3PA coefficient (γ), third-order nonlinear susceptibility (χ(3)) and figure of merit (F) have been calculated.

  • Nonlinear optical studies of newly synthesized polythiophenes containing pyridine and 1,3,4-oxadiazole units
    P. Poornesh, P.K. Hegde, M.G. Manjunatha, G. Umesh, and A.V. Adhikari

    Polymer Engineering and Science, ISSN: 00323888, eISSN: 15482634, Pages: 875-880, Published: May 2009 Wiley
    We report measurements of the third-order nonlinear optical properties of a newly synthesized thiophenebased copolymer. The nonlinear transmission measurements were performed on the copolymer dissolved in tetrahydrofuran by employing the single beam Z-scan technique. Q-switched laser output at 532-nm wavelength was used for this purpose. The nonlinear absorption coefficient, b, nonlinear refractive index, n2, and the real and imaginary parts of third-order susceptibility, v(3), were, 18.93 cm/GW, 3.037 3 10�17 m2/W (�1.022 3 10�10 esu), 1.512 3 10�20 m2/V2(�1.080 3 10�12 esu) and 0.399 3 10�20 m2/V2 (0.285 3 10�12 esu), respectively. The excited state absorption crosssection rexc, was found to be larger than the ground state absorption crosssection rg, indicating reverse saturable absorption (RSA) in the copolymer sample. The copolymer exhibits an optical power limiting threshold of about 120 lJ and saturated output of less than 80 lJ. Hence, the copolymer seems to be a promising material for photonic device applications. POLYM. ENG. SCI., 49:875–880, 2009.

  • Corrosion inhibition of mild steel in acid media by quinolinyl thiopropano hydrazone
    Indian Journal of Chemical Technology, ISSN: 0971457X, Pages: 162-174, Published: March 2009

  • Synthesis of some new pyrazolines and isoxazoles carrying 4-methylthiophenyl moiety as potential analgesic and antiinflammatory agents
    Indian Journal of Chemistry - Section B Organic and Medicinal Chemistry, ISSN: 03764699, Pages: 430-437, Published: March 2009

  • Synthesis of some new 4-styryltetrazolo[1,5-a]quinoxaline and 1-substituted-4-styryl[1,2,4]triazolo[4,3-a]quinoxaline derivatives as potent anticonvulsants
    Shivananda Wagle, Airody Vasudeva Adhikari, and Nalilu Suchetha Kumari

    European Journal of Medicinal Chemistry, ISSN: 02235234, eISSN: 17683254, Pages: 1135-1143, Published: March 2009 Elsevier BV
    4-Methyltetrazolo[1,5-a]quinoxaline (3) was prepared by the azide cyclocondensation of 2-chloro-3-methylquinoxaline (2). The reaction of 3 with aromatic aldehydes furnished 4-styryltetrazolo[1,5-a]quinoxalines (4a-f). Compound 2, on treatment with hydrazine hydrate gave 2-hydrazino-3-methylquinoxaline (5). The ring closure of 5 was achieved by the reaction of orthoesters and trifluoroacetic acid to yield 4-methyl-1-(substituted)[1,2,4]triazolo[4,3-a]quinoxalines (7a-c). Further, reaction of 7a-c with different aromatic aldehydes furnished the title compounds, 4-styryl-1-(substituted)[1,2,4]triazolo[4,3-a]quinoxalines (8a-i) in good yield. In another scheme, the hydrazino compound 5 was treated with different aromatic aldehydes to yield corresponding N-arylidenehydrazino quinoxalines (6a-d). Further, the oxidative cyclization of hydrazones by nitrobenzene yielded 1-aryl-4-methyl[1,2,4]triazolo[4,3-a]quinoxalines (7d-g), which on condensation with aromatic aldehydes gave the title compounds, 1-aryl-4-styryl[1,2,4]triazolo[4,3-a]quinoxalines (8j-u). The newly synthesized compounds have been characterized by FTIR, (1)H NMR, (13)C NMR and mass spectral data, followed by elemental analysis. Some of the compounds were screened for in vivo anticonvulsant activity. Few of them exhibited promising results.

  • Design and synthesis of new donor-acceptor type conjugated copolymers derived from thiophenes
    M.G. Manjunatha, A.V. Adhikari, and P.K. Hegde

    European Polymer Journal, ISSN: 00143057, Pages: 763-771, Published: March 2009 Elsevier BV

  • Third-order nonlinear optical susceptibilities of new copolymers containing alternate 3,4-dialkoxythiophene and (1,3,4-oxadiazolyl)pyridine moieties
    Pramod Kumar Hegde, A. Vasudeva Adhikari, M.G. Manjunatha, P. Poornesh, and G. Umesh

    Optical Materials, ISSN: 09253467, Pages: 1000-1006, Published: April 2009 Elsevier BV
    A new series of conjugated copolymers (P1–P3) consisting of alternate 3,4-dialkoxythiophene and (1,3,4-oxadiazolyl)pyridine moieties have been synthesized using the precursor polyhydrazide route. They have been characterized by FTIR, 1H NMR spectral and elemental analyses. These copolymers possess well defined structure and exhibit good thermal stability with the onset decomposition temperature in nitrogen at around 300 �C. Their molecular weights were determined by gel permeation chromatography (GPC). The optical and charge-transporting properties of the copolymers were investigated by UV–visible spectroscopy, fluorescence emission spectroscopy and cyclic voltammetry. Their UV–visible absorption spectra showed a kmax at around 342 nm and displayed bluish-green fluorescence in solution state. The band gaps were found to be at about 2.55 eV for all the copolymers. The third-order nonlinear optical properties (NLO) of these copolymers were studied by Z-scan technique. The measurements were performed at 532 nm with 7 ns laser pulses using a Nd:YAG laser in solution form. The real part of v(3) were estimated to be �0.881 � 10�12, �0.901 � 10�12 and �1.030 � 10�12 esu for P1, P2 and P3 respectively. The imaginary part of v(3) for the copolymers P1, P2 and P3 were determined to be 0.192 � 10�12, 0.253 � 10�12 and 0.272 � 10�12 esu respectively. The copolymers exhibit strong reverse saturable absorption and good optical limiting behaviour at 532 nm.

  • Inhibition of corrosion of mild steel in acid media by N'-benzylidene-3- (quinolin-4-ylthio)propanohydrazide
    V. Ramesh Saliyan and Airody Vasudeva Adhikari

    Bulletin of Materials Science, ISSN: 02504707, Pages: 699-711, Published: August 2008 Springer Science and Business Media LLC

  • (E)-1-[4-(Methyl-sulfan-yl)phen-yl]-3-phenyl-prop-2-en-1-one
    A. Thiruvalluvar, M. Subramanyam, R. J. Butcher, T. Karabasanagouda, and A. V. Adhikari

    Acta Crystallographica Section E: Structure Reports Online, ISSN: 16005368, eISSN: 16005368, Published: 2008 International Union of Crystallography (IUCr)

  • Synthesis of some novel 2,4-disubstituted thiazoles as possible antimicrobial agents
    Shivananda Wagle, Airody Vasudeva Adhikari, and Nalilu Suchetha Kumari

    Phosphorus, Sulfur and Silicon and the Related Elements, ISSN: 10426507, eISSN: 15635325, Volume: 183, Pages: 1285-1300, Published: May 2008 Informa UK Limited

  • Nonlinear optical properties of p-(N,N-dimethylamino)dibenzylideneacetone doped polymer
    A. John Kiran, Nooji Satheesh Rai, D. Udayakumar, K. Chandrasekharan, B. Kalluraya, Reji Philip, H.D. Shashikala, and A.V. Adhikari

    Materials Research Bulletin, ISSN: 00255408, Pages: 707-713, Published: 4 March 2008 Elsevier BV

  • Synthesis of some new 2-(3-methyl-7-substituted-2-oxoquinoxalinyl)-5-(aryl) -1,3,4-oxadiazoles as potential non-steroidal anti-inflammatory and analgesic agents
    Indian Journal of Chemistry - Section B Organic and Medicinal Chemistry, ISSN: 03764699, Pages: 439-448, Published: March 2008

  • Quinolin-5-ylmethylene-3-{[8-(trifluoromethyl)quinolin-4-yl]thio}propanohydrazide as an effective inhibitor of mild steel corrosion in HCl solution
    V. Ramesh Saliyan and Airody Vasudeva Adhikari

    Corrosion Science, ISSN: 0010938X, Pages: 55-61, Published: January 2008 Elsevier BV


  • Synthesis of some new 2-(4-alkylthiophenoxy)-4-substituted-1, 3-thiazoles as possible anti-inflammatory and antimicrobial agents
    Indian Journal of Chemistry - Section B Organic and Medicinal Chemistry, ISSN: 03764699, Pages: 144-152, Published: January 2008

  • Synthesis and nonlinear optical characterization of copolymers containing alternating 3,4-dialkoxythiophene and 1,3,4-oxadiazolydbenzene units
    D. Udayakumar, A. John Kiran, A. V. Adhikari, K. Chandrasekharan, and H. D. Shashikala

    Journal of Applied Polymer Science, ISSN: 00218995, eISSN: 10974628, Volume: 106, Pages: 3033-3039, Published: 5 December 2007 Wiley

  • Synthesis and antimicrobial activities of some novel 1,3,4-oxadiazoles carrying alkylthio and alkylsulphonyl phenoxy moieties
    T. Karabasanagouda, Airody Vasudeva Adhikari, and N. Suchetha Shetty

    Phosphorus, Sulfur and Silicon and the Related Elements, ISSN: 10426507, eISSN: 15635325, Volume: 182, Pages: 2925-2941, Published: December 2007 Informa UK Limited

  • (2E)-3-(4-Chloro-phen-yl)-1-[4-(methyl-sulfan-yl)phen-yl]prop-2-en-1-one
    A. Thiruvalluvar, M. Subramanyam, R. J. Butcher, A. V. Adhikari, and T. Karabasanagouda

    Acta Crystallographica Section E: Structure Reports Online, ISSN: 16005368, eISSN: 16005368, Published: 9 November 2007 International Union of Crystallography (IUCr)

  • 2-Chloro-3-methyl-quinoxaline
    A. Thiruvalluvar, M. Subramanyam, R. J. Butcher, A. V. Adhikari, and S. Wagle

    Acta Crystallographica Section E: Structure Reports Online, ISSN: 16005368, eISSN: 16005368, Published: 9 November 2007 International Union of Crystallography (IUCr)

  • 3-[(E)-4-(2-Nitro-phen-yl)vin-yl]-1-(tri-fluoro-meth-yl)-1,2,4-triazolo[4, 3-a]quinoxaline
    A. Thiruvalluvar, M. Subramanyam, R. J. Butcher, S. Wagle, and A. V. Adhikari

    Acta Crystallographica Section E: Structure Reports Online, ISSN: 16005368, eISSN: 16005368, Published: 9 November 2007 International Union of Crystallography (IUCr)

  • (2E)-3-(4-Fluoro-phen-yl)-1-(thien-2-yl)prop-2-en-1-one
    A. Thiruvalluvar, M. Subramanyam, R. J. Butcher, A. V. Adhikari, and S. Wagle

    Acta Crystallographica Section E: Structure Reports Online, ISSN: 16005368, eISSN: 16005368, Published: 9 November 2007 International Union of Crystallography (IUCr)

  • Synthesis and characterization of novel conjugated copolymers containing 3,4-dialkoxythiophene and 1,3,4-oxadiazole units
    D. Udayakumar and A. Vasudeva Adhikari

    European Polymer Journal, ISSN: 00143057, Pages: 3488-3499, Published: August 2007 Elsevier BV

  • Synthesis and antimicrobial activities of some novel 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles and 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazines carrying thioalkyl and sulphonyl phenoxy moieties
    T. Karabasanagouda, Airody Vasudeva Adhikari, and N. Suchetha Shetty

    European Journal of Medicinal Chemistry, ISSN: 02235234, eISSN: 17683254, Pages: 521-529, Published: April 2007 Elsevier BV

  • Synthesis and characterization of fluorescent poly(oxadiazole)s containing 3,4-dialkoxythiophenes
    D. Udayakumar and Airody Vasudeva Adhikari

    Optical Materials, ISSN: 09253467, Pages: 1710-1718, Published: August 2007 Elsevier BV

  • Third-order nonlinear optical studies of newly synthesized polyoxadiazoles containing 3,4-dialkoxythiophenes
    D. Udayakumar, A. John Kiran, A. Vasudeva Adhikari, K. Chandrasekharan, G. Umesh, and H.D. Shashikala

    Chemical Physics, ISSN: 03010104, Volume: 331, Pages: 125-130, Published: 11 December 2006 Elsevier BV

  • Synthesis and characterization of new light-emitting copolymers containing 3,4-dialkoxythiophenes
    D. Udayakumar and A.Vasudeva Adhikari

    Synthetic Metals, ISSN: 03796779, Volume: 156, Issue: 18-20, Pages: 1168-1173, Published: 1 November 2006 Elsevier BV

  • Z-scan and degenerate four wave mixing studies on newly synthesized copolymers containing alternating substituted thiophene and 1,3,4-oxadiazole units
    A John Kiran, D Udayakumar, K Chandrasekharan, A V Adhikari, and H D Shashikala

    Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN: 09534075, eISSN: 13616455, Pages: 3747-3756, Published: 28 September 2006 IOP Publishing

  • Trifluoromethyl-quinolin-yl-thio-propanohydrazide as an effective inhibitor of mild steel corrosion in HCl solution
    Transactions of the SAEST (Society for Advancement of Electrochemical Science and Technology), ISSN: 00360678, Pages: 88-93, Published: April 2006

  • Synthesis and antimicrobial activities of some isoxazolo[5',4':4,5]pyrimido[6,1-c][1,2,4]triazine derivatives
    Journal of the Indian Chemical Society, ISSN: 00194522, Pages: 500-503, Published: 1988

  • Syntheses of 3,6‐Substituted‐4‐(3′,4′,5′‐Substituted‐1′‐pyrazolyl)‐isoxazolo[5,4‐d]pyrimidines as Potential Antiinflammatory Agents
    Vasudeva A. Adhikari and Virupax V. Badiger

    Archiv der Pharmazie, ISSN: 03656233, eISSN: 15214184, Volume: 320, Pages: 1124-1131, Published: November 1987 Wiley

RECENT SCHOLAR PUBLICATIONS

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    >140 Publications, one book chapter, and 10 conference proceedings.

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    Research projects funded by DST, DRDO, DEIT completed

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    SOCIAL, ECONOMIC, or ACADEMIC BENEFITS

    Biofuel awareness in Dakshina Kannada district through KSBDB, KoG, Bangalore: Production and use of Biodiesel from non-edible oils and Biogas from agro- and kitchen-wastes.