@karunya.edu
Associate Professor, Department of Applied Chemistry
Karunya Institute of Technology and Sciences
Coordination Chemistry of Cobalt Complexes
Electrocatalysis
Electrochemical sensors
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Sumi Sundaresan, Subramanian Sowmya, and Vijendran Vijaikanth
Wiley
AbstractSunset Yellow (SY) is an azo dye used in various food and pharmaceutical industries that deserves special attention because of its allergic and carcinogenic properties. Recently, electrochemical techniques have come to the spotlight because of their high sensitivity, simplicity and rapidity as compared to other techniques. In this work, we have developed a cost‐effective and stable electrochemical sensor by a simple method using Vitamin B12‐derived cobalt oxide coupled with g‐C3N4 (V12‐CoO/gCN) modified Au electrode. The composite prepared for the sensor was characterized using techniques such as FTIR, Powder XRD, SEM analysis, EDAX, and mapping. For electrochemical sensing of the dye Sunset Yellow, CV, DPV, and LSV techniques have been used, out of which DPV shows a better detection limit of 1.39 nM followed by LSV and CV that displayed detection limits of 3.3 nM and 4.14 nM respectively. When 5 real samples obtained from the local market are analyzed using the DPV technique, the detection limit is obtained in the range between 2.1 nM and 6.9 nM. This method leads to the development of an electrochemical sensor for the detection of Sunset Yellow to get a lower detection limit that can be used in food toxicology and related fields.
Sumi Sundaresan, Subramanian Sowmya, and Vijendran Vijaikanth
Wiley
AbstractA new bipyridine bridged dicobaloxime complex BrCo(dpgh)2(4,4’‐bipyridine)Co(dpgH)2Br was synthesized and characterized by standard spectroscopic techniques. The synthesized complex was employed as an electrocatalyst for the proton reduction in the presence of acetic acid as an acid source. The catalytic efficiency was calculated to be 0.379. Subsequently the nanocomposite of the complex was prepared with g‐C3N4 nanosheet by hydrothermal method and the composite material was characterized by standard physical characterization techniques. When the nanocomposite was employed as a catalyst for electrochemical sensing of toxic food color Metanil yellow dye using gold electrode, the LOD value was found to be 0.09 nM. These studies show that the dicobaloxime acts as a bifunctional catalyst towards electrochemical proton reduction and for the detection of Metanil yellow dye.
Sumi Sundaresan and Vijendran Vijaikanth
Springer Science and Business Media LLC
S. Boopalan, Aneesha Antony, Nienu Susan Loyid, V. Vijaikanth, and S. Murugan
Informa UK Limited
Subramanian Sowmya and Vijendran Vijaikanth
Elsevier BV
Ramachandran John Wesley, Subramanian Sowmya, Arulappan Durairaj, Romiyo Justinabraham, Vijendran Vijaikanth, Asir Obadiah, and Samuel Vasanthkumar
Elsevier BV
Ramachandran John Wesley, Subramanian Sowmya, Arulappan Durairaj, Romiyo Justinabraham, Vijendran Vijaikanth, and Samuel Vasanthkumar
Springer Science and Business Media LLC
Subramanian Sowmya and Vijendran Vijaikanth
American Chemical Society (ACS)
Due to environmental contamination and the depletion of energy supplies, it is very important to develop low-cost, high-performance, multifunctional electrocatalysts for energy conversion and storage systems. Herein, we report the development of cost-effective modified electrodes containing g-C3N4/chlorocobaloxime composites (C1–C4) and their electrocatalytic behavior toward the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), followed by their energy-storage applications. A series of chlorocobaloximes {ClCo(dpgH)2B} with diphenylglyoxime (dpgH) and neutral bases (B) containing a carboxylic acid moiety (isonicotinic acid, pyridine-3,5-dicarboxylic acid, indole-2-carboxylic acid, and p-aminobenzoic acid) have been synthesized and characterized by spectroscopic techniques. The nanocomposites of g-C3N4/chlorocobaloximes are prepared and characterized by Fourier transform infrared (FTIR) spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy (UV-DRS), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray photoelectron spectroscopy (XPS), particle size distribution analysis (PSA), Brunauer–Emmett–Teller (BET), and energy dispersive X-ray analysis (EDAX) techniques. The composite coatings exhibit enhanced HER performance at lower overpotential and with a lower Tafel slope. When the water-splitting reactions are studied using 0.5 M H2SO4 and 0.5 M KOH as electrolytic solutions, the composite g-C3N4/C2 containing pyridine-3,5-dicarboxylic acid as a neutral base shows excellent HER activity with a lower overpotential of 173 mV at −10 mA cm–2 and OER activity with a lower overpotential of 303 mV. The HER reaction takes place through the Volmer–Heyrovský mechanism, where the desorption step is the rate-determining step. Among the synthesized nanocomposites, the nanocomposite g-C3N4/C2 shows higher efficiency toward both HER and OER reactions, with a lower Tafel slope of 55 mV dec–1 for HER and 114 mV dec–1 for OER than the other nanocomposites. The overall water-splitting studies of the composite g-C3N4/C2 in 0.5 M KOH indicate that the evolution of hydrogen and oxygen occurs constantly up to 120 h. The supercapacitance applications studied using cyclic voltammetry and charge–discharge studies indicate that the nanocomposite g-C3N4/C1 shows a good specific capacitance of 236 F g–1 at 0.5 A g–1 compared to others. The increased electrochemical performance of the synthesized nanocomposites is due to the incorporation of electron-withdrawing carboxylic-acid-functionalized neutral bases present in cobaloximes, which increases electron mobility. The incorporation of a cobaloxime complex into a g-C3N4 nanosheet enhances the electrocatalytic behavior of the nanosheet, and its performance can further be fine-tuned by systematic variation in the structure of cobaloxime by changing the halide ion, dioxime, the neutral base ligand, or the substituent.
Subramanian Sowmya, Prince Makarios Paul, Sitheshwaran Boopalan, Angamuthu Abiram, François Michaud, and Vijendran Vijaikanth
Elsevier BV
Romiyo Justinabraham, Subramanian Sowmya, Arulappan Durairaj, Ramachandran John Wesley, Vijendran Vijaikanth, Asir Obadiah, and Samuel Vasanthkumar
Springer Science and Business Media LLC
Romiyo Justinabraham, Subramanian Sowmya, Arulappan Durairaj, Thangavel Sakthivel, Ramachandran John Wesley, Vijendran Vijaikanth, and Samuel Vasanthkumar
Elsevier BV
Subramanian Sowmya and Vijendran Vijaikanth
Wiley
Angel Green Samuel, Sowmya Subramanian, Vijaikanth Vijendran, and Jebasingh Bhagavathsingh
Frontiers Media SA
We report stable and heterogeneous graphene oxide (GO)–intercalated copper as an efficient catalyst for the organic transformations in green solvents. The GO-intercalated copper(II) complex of bis(1,4,7,10-tetraazacyclododecane) [Cu(II)-bis-cyclen] was prepared by a facile synthetic approach with a high dilution technique. The as-prepared GO-Cu(II)-bis-cyclen nanocomposite was used as a click catalyst for the 1,3 dipolar Huisgen cycloaddition reaction of terminal alkyne and azide substrates. On directing a great deal of attention toward the feasibility of the rapid electron transfer rate of the catalyst in proliferating the yield of 1,2,3-triazole products, the click catalyst GO-Cu(II)-bis-cyclen nanocomposite was designed and synthesized via non-covalent functionalization. The presence of a higher coordination site in an efficient 2D nanocomposite promotes the stabilization of Cu(I) L-acetylide intermediate during the catalytic cycle initiated by the addition of reductants. From the XRD analysis, the enhancement in the d-interlayer spacing of 1.04 nm was observed due to the intercalation of the Cu(II)-bis-cyclen complex in between the GO basal planes. It was also characterized by XPS, FT-IR, RAMAN, UV, SEM, AFM, and TGA techniques. The recyclability of the heterogeneous catalyst [GO-Cu(II)-cyclen] with the solvent effect has also been studied. This class of GO-Cu(II)-bis-cyclen nanocomposite paves the way for bioconjugation of macromolecules through the click chemistry approach.
V. Vijaikanth, S. Vasuki, C. Immanuel David, L. Chandran, S. Sowmya, and S. Murugan
Asian Journal of Chemistry
The inorganic cobaloximes of type [Co(Cl)(dmgH)2B]; where dmgH = dimethyl glyoxime and B = neutral bases: glycine, ethyl amine, 2-aminopyridine, 4-aminopyridine, 2,6-diaminopyridine, aniline and 1-napthylamine have been synthesized. The synthesized cobaloximes were characterized by IR, UV-visible, 1H NMR and 13C NMR spectroscopic techniques. The cobaloxime complexes were screened for their antibacterial activity against methicillin resistant Staphylococcus aureus (MRSA) and Acinetobacter baumannii by the zone of inhibition test, biofilm eradication on biomaterial using catheter and modified Congo red agar method. It has been found that the cobaloxime complexes exhibit inhibition against both gram positive and gram negative bacteria and the cobaloximes showed better inhibition towards Gram-negative bacteria compared to Gram-positive bacteria.
S. Sowmya, L. Sridhar, and V. Vijaikanth
Elsevier BV
Vijendran Vijaikanth, Guangchun Li, and Thomas W. Swaddle
American Chemical Society (ACS)
Rate constants kel obtained by impedance spectroscopy for the reduction of Ru(NH3)6(3+) at polycrystalline Pt and Au ultramicroelectrodes depend strongly on the identity and concentration of the anion present in the order CF3SO3(-) < Cl(-) < ClO4(-), but not on the cation of the supporting electrolyte (Na(+), K(+), H(+)). For Cl(-) as the sole anion present, kel is directly proportional to the total [Cl(-)], such that kel would be zero if Cl(-) were hypothetically absent, indicating that Cl(-) is directly involved in mediation of the Ru(NH3)6(3+/2+) electron transfer. For CF3SO3(-) as the sole counterion, the dependence of kel on the total [CF3SO3(-)] is not linear, possibly because blocking of the available electrode surface becomes dominant at high triflate concentrations. Volumes of activation ΔVel(⧧) for reduction of Ru(NH3)6(3+) at an electrode in presence of Cl(-) or CF3SO3(-) are much more negative than predictions based on theory (Swaddle, T. W. Chem. Rev.2005, 105, 2573) that has been successful with other electron transfer reactions but which does not take into account the involvement of the anions in the activation process. The strongly negative ΔVel(⧧) values probably reflect solvation increases peculiar to activation processes of Ru(III/II) am(m)ine complexes, possibly together with promotion of desorption of surface-blocking Cl(-) or CF3SO3(-) from electrodes by applied pressure. Frumkin corrections for Ru(NH3)6(3+) within the diffuse double layer would make ΔVel(⧧) even more negative than is observed, although the corrections would be small. The strongly negative ΔVel(⧧) values are inconsistent with reduction of Ru(NH3)6(3+) in direct contact with the metallic electrode surface, which would entail substantial dehydration of both the electrode and Ru(NH3)6(3+). Reduction of Ru(NH3)6(3+) can be regarded as taking place in hard contact with adsorbed water at the outer Helmholtz plane.
Vijendran Vijaikanth, Jean-François Capon, Frédéric Gloaguen, François Y. Pétillon, Philippe Schollhammer, and Jean Talarmin
Elsevier BV
V. Vijaikanth, B. D. Gupta, Debaprasad Mandal, and Shashank Shekhar
American Chemical Society (ACS)
m-Xylylene-bridged dicobaloximes with a substituent at the 2-position having varying electronic and steric properties have been synthesized and characterized by 1H and 13C NMR spectroscopy. The variable-temperature 1H NMR study of these complexes shows that the electronic cis influence is an important phenomenon for the Co−C bond rotation. The coalescence temperature of the dioxime protons correlates well with the ortho substituent constant. The crystal structure of a 2-nitro-m-xylylene-bridged dicobaloxime, Py(dmgH)2Co-CH2-(2-NO2-1,3-C6H3)-CH2-Co(dmgH)2Py, is reported. The X-ray structural data support the 1H NMR findings.
V. Vijaikanth, Jean-François Capon, Frédéric Gloaguen, Philippe Schollhammer, and Jean Talarmin
Elsevier BV
B. D. Gupta, V. Vijaikanth, and Veena Singh
American Chemical Society (ACS)
Organo-bridged dicobaloximes with four different dioximes Py(L)2CoCH2-R-CH2Co(L)2Py (L = dmgH, dpgH, chgH, and gH) have been synthesized and characterized by 1H and 13C NMR and FAB mass spectroscopy. The cis influencing order observed in dicobaloximes is similar to the previously observed order in monocobaloximes. The cyclic voltammetric results show that an irreversible single-step two-electron reduction of CoIII to CoI takes place. The Co−C bond in 4a cleaves during crystallization and results in the formation of o-vinylbenzyl cobaloxime. The variable-temperature 1H NMR study suggests that the Co−C bond rotation is restricted and its magnitude depends on both the nature of the bridging ligand and the dioxime.
B.D. Gupta and V. Vijaikanth
Elsevier BV
B.D. Gupta, Kushal Qanungo, R. Yamuna, Ashutosh Pandey, Usha Tewari, V. Vijaikanth, Veena Singh, T. Barclay, and W. Cordes
Elsevier BV
B.D. Gupta, V. Singh, K. Qanungo, V. Vijaikanth, R. Yamuna, T. Barclay, and W. Cordes
Elsevier BV