Keshaba Nanda Parida
@iisertvm.ac.in
CSIR Pool Scientist (Chemistry)
Indian Institute of Science Education and Research Thiruvananthapuram
RESEARCH, TEACHING, or OTHER INTERESTS
Organic Chemistry, Materials Chemistry, Multidisciplinary
Scopus Publications
Scopus Publications
Umar Rashid, William Bro-Jørgensen, KB Harilal, PA Sreelakshmi, Reetu Rani Mondal, Varun Chittari Pisharam, Keshaba N. Parida, K. Geetharani, Joseph M. Hamill, and Veerabhadrarao Kaliginedi
American Chemical Society (ACS)
Chemistry of the Au-S interface at the nanoscale is one of the most complex systems to study, as the nature and strength of the Au-S bond change under different experimental conditions. In this study, using mechanically controlled break junction technique, we probed the conductance and analyzed Flicker noise for several aliphatic and aromatic thiol derivatives and thioethers. We demonstrate that Flicker noise can be used to unambiguously differentiate between stronger chemisorption (Au-SR) and weaker physisorption (Au-SRR') type interactions. The Flicker noise measurements indicate that the gold rearrangement in chemisorbed Au-SR junctions resembles that of the Au rearrangement in pure Au-Au metal contact breaking, which is independent of the molecular backbone structure and the resulting conductance. In contrast, thioethers showed the formation of a weaker physisorbed Au-SRR' type bond, and the Flicker noise measurement indicates the changes in the Au-anchoring group interface but not the Au-Au rearrangement like that in the Au-SR case. Additionally, by employing single-molecular conductance and Flicker noise analysis, we have probed the interfacial electric field-catalyzed ring-opening reaction of cyclic thioether under mild environmental conditions, which otherwise requires harsh chemical conditions for cleavage of the C-S bond. All of our conductance measurements are complemented by NEGF transport calculations. This study illustrates that the single-molecule conductance, together with the Flicker noise measurements can be used to tune and monitor chemical reactions at the single-molecule level.
Ishita Neogi and Keshaba N. Parida
Wiley
AbstractThe synthesis of chiral organic molecules is a purity‐driven research that has become an essential part of our lives due to their applications in pharmaceuticals. Contemporary research focuses on the exploration of synthetic protocols that obviate the use/generation of hazardous chemicals. In this regard, dioxiranes are readily accessed as a reagent solution or catalyst (in situ) from the reaction of ketone with a co‐oxidant like Oxone® or H2O2; the latter makes the protocol very green and inexpensive. It has shown the potential to replace transition metal‐based oxygenation protocols. The dioxirane‐mediated asymmetric reactions include oxidations, epoxidations, C−H hydroxylations, etc. Both stoichiometric and catalytic protocols of dioxiranes are been explored for the oxyfunctionalization of chiral natural product derivatives such as Penicillin, nucleosides, amino acids, carbohydrates, etc. In addition, these are employed as key oxygenation agents during the synthesis of natural products like (+)‐Plagiogyrin A, Portimine, Taxol, Bryostatin, dafachronic acid, majucinoids, eldecalcitol, Spirochensilide A, etc. The review consolidates the development of both achiral and chiral dioxiranes in application to asymmetric synthesis and oxygenation of chiral molecules.
Ajeet Chandra, Navin Yadav, Soumen Payra, and Keshaba N. Parida
American Chemical Society (ACS)
o-Iodoxybenzoic acid (IBX) and Dess-Martin periodinane (DMP) are employed for thiol to thiosulfonate conversion at rt. DMP is better than IBX in terms of reaction rate, conversion, and required equivalents. IBX-mediated oxidation of benzyl thiols produced thiosulfonates, whereas DMP afforded O-benzyl esters. The one-pot conversion of a thiol to an ester is unprecedented; this atom-economic transformation has potential for functional group transformations (FGTs), e.g., an alcohol and an aldehyde are accessed from benzyl thiol.
Keshaba N. Parida and J. Narasimha Moorthy
Wiley
Hypervalent iodine (III and V) compounds exhibit positional isomerization through pseudorotation or twisting; the latter have been invoked for the stability as well as the reactivities of λ3- and λ5-iodanes. By judicious exploitation of sterics, the twisting process in iodanes can be facilitated to promote reactivity. For example, ortho-substitution in λ3- and λ5-iodanes accelerates α-tosyloxylation of ketones and oxidation of alcohols. The enhancement of reactivity arises from sterically-induced non-planarity and the resultant weakening of the 3c-4e bonds involving the hypervalent iodine atom. The ortho-substitution constitutes an important strategy to maneuver reactivity, control selectivity, and develop new catalysts, including chiral, for diverse reactions. This review entails coverage of the literature developments in regard to the effect of substituents and twisting/pseudorotation on the stability as well as the reactivity of hypervalent λ3- and λ5-iodanes, and the application of the latter for synthetic transformations.
Keshaba N. Parida and Jarugu Narasimha Moorthy
Georg Thieme Verlag KG
Abstract o-Iodoxybenzoic acid (IBX) is an oxidation reagent that has surged into prominence in the last two decades. It is cost-effective, environmentally benign, and readily prepared from o-iodobenzoic acid. However, its insolubility in common organic solvents and explosive attributes upon impact and heating are debilitating disadvantages. The development of modified IBXs (mIBXs) that exhibit improved solubility and enhanced reactivity, and obviate explosive attributes by judicious manipulation of the structure of IBX has been an incessant endeavor. In this account, common organic solvent-soluble mIBXs developed in our research group are collated with a discussion of the rationale underlying the design principles. Steric build-up around the iodoxolone moiety that is responsible for strong intermolecular interactions within the crystal lattice of IBX constitutes the key consideration in the design and development of modified λ5-iodanes that are reactive and sparingly soluble in common organic solvents. In situ generation of mIBXs from precursor iodo-acids in the presence of Oxone® permits their employment as organocatalysts for facile oxidative transformations. Reactive mIBXs generated in situ from precursor modified iodo-acids (mIAs, II) in the presence of Oxone® may offer unrivaled prospects for cost-effective oxidations. Applications of mIBXs, generated in situ or otherwise, for efficient oxidations are consolidated.1 Introduction2 Design and Synthesis of Modified IBXs and their Precursors Iodo-Acids3 Catalytic Oxidations with Modified IBXs3.1 Oxidation of Alcohols3.2 Oxidation of 1,2-Diols3.3 Conversion of Diols into Lactones3.4 One-Pot Oxidative Cleavage of Olefins3.5 One-Pot Transformation of Olefins into α-Bromo- and α-Azidoketones4 Conclusions
Gourab Mohanty, Anjitha Sebastian, Haritha S., Keshaba N. Parida, and Ishita Neogi
Royal Society of Chemistry (RSC)
Spacer manoeuvring by fluorination to achieve ambient stability in perovskites towards oxygen, moisture, and light.
Tarek H. El-Assaad, Jayden Zhu, Anjitha Sebastian, Dominic V. McGrath, Ishita Neogi, and Keshaba N. Parida
Royal Society of Chemistry (RSC)
Dioxiranes are extremely useful multitasking agents for a broad spectrum of chemical transformations. This review collates the history of dioxiranes over the last fifty years in the realm of organic and materials chemistry.
Nathan D. Bamberger, Dylan Dyer, Keshaba N. Parida, Tarek H. El-Assaad, Dawson Pursell, Dominic V. McGrath, Manuel Smeu, and Oliver L. A. Monti
American Chemical Society (ACS)
Structure-function relationships constitute an important tool to investigate the fundamental principles of molecular electronics. Most commonly, this involves identifying a potentially important molecular structural element, followed by designing and synthesizing a set of related organic molecules, and finally interpretation of their experimental and/or computational quantum transport properties in the light of this structural element. Though this has been extremely powerful in many instances, we demonstrate here the common need for more nuanced relationships even for relatively simple structures, using both experimental and computational results for a series of stilbene derivatives as a case study. In particular, we show that the presence of multiple competing and subtle structural factors can combine in unexpected ways to control quantum transport in these molecules. Our results clarify the reasons for previous widely varying and often contradictory reports on charge-transport in stilbene derivatives, and highlight the need for refined multidimensional structure-property relationships in single molecule
Nathan D. Bamberger, Dylan Dyer, Keshaba N. Parida, Dominic V. McGrath, and Oliver L. A. Monti
American Chemical Society (ACS)
Most single-molecule transport experiments produce large and stochastic datasets containing a wide range of behaviors, presenting both a challenge to their analysis, but also an opportunity for discovering new physical insights. Recently, several unsupervised clustering algorithms have been developed to help extract and separate distinct features from single-molecule transport data. However, these clustering approaches are in general neither designed nor appropriate for identifying very rare features and behaviors, such as switching events, chemical reactions, or particular binding modes, which may nonetheless contain physically meaningful information. In this work we introduce a completely new analysis framework specifically designed for rare event detection in singlemolecule break junction data as a necessary component to enable such studies in the future. Our approach leverages the concept of correlations of breaking traces with their own history to robustly identify paths through distanceconductance space that correspond to reproducible rare behaviors. As both a demonstrative and important example, we focus on rare conductance plateaus for short molecules, which can be essentially invisible when examining raw data. We show that our grid-based correlation tools successfully and reproducibly locate these rare plateaus in real experimental datasets. This result provides useful insight into the nanoscopic junction environment, enables a broader variety of molecules to be considered in the future, and validates our new approach as a powerful tool for detecting rare yet meaningful behaviors in single molecule transport data.
Adeeba Ahmed, Arif Ali, Mohsina Ahmed, Keshaba N. Parida, Musheer Ahmad, and Aiman Ahmad
Elsevier BV
Abstract Here we report the synthesis of a 3D coordination polymer, [Cd4(CH3COO)4(μ-OH)4·C2H5OH]n (CP1) of cadmium acetate via solvothermal synthesis under high temperature and pressure conditions for 72 h. It was characterized by single crystal X-ray diffraction (SCXRD), FTIR, powder X-ray diffraction (PXRD) and thermogravimetric (TGA) techniques. Surface area and porosity were determined by BET analysis. Further, TEM results show structural variability and morphological information of CP1. The X-ray analysis confirms that the CP1 was crystallized in a monoclinic system with square pyramidal geometry resulting from the bidentate acetate ions and hydroxide ions. The topological studies suggest that the CP1 is having binodal nodes with kgd topological network. The CP1 was employed as dye adsorbent for both MB (methylene blue) and MO (methyl orange) dyes, which are considered as harmful organic pollutants. Moreover, CP1 has shown selective adsorption with good adsorption efficiency for MB dye at room temperature and high pH value. The adsorption mechanism was considered to be based on the electrostatic and H-bonding interactions. The adsorption kinetic model reveals that it follows pseudo second order kinetics. Interestingly, CP1 is displaying unique structural and topological features with better adsorption properties towards organic pollutants, hence it can be employed as an effective dye adsorbent for future applications.
Jeffrey A. Ivie, Nathan D. Bamberger, Keshaba N. Parida, Stuart Shepard, Dylan Dyer, Aldilene Saraiva-Souza, Roland Himmelhuber, Dominic V. McGrath, Manuel Smeu, and Oliver L.A. Monti
American Chemical Society (ACS)
The rational design of single-molecule electrical components requires a deep and predictive understanding of structure-function relationships. Here, we explore the relationship between chemical substituents and the conductance of metal-single-molecule-metal junctions, using functionalized oligophenylenevinylenes as a model system. Using a combination of mechanically controlled break-junction experiments and various levels of theory including non-equilibrium Green's functions, we demonstrate that the connection between gas-phase molecular electronic structure and in-junction molecular conductance is complicated by the involvement of multiple mutually correlated and opposing effects that contribute to energy-level alignment in the junction. We propose that these opposing correlations represent powerful new "design principles" because their physical origins make them broadly applicable, and they are capable of predicting the direction and relative magnitude of observed conductance trends. In particular, we show that they are consistent with the observed conductance variability not just within our own experimental results but also within disparate molecular series reported in the literature and, crucially, with the trend in variability across these molecular series, which previous simple models fail to explain. The design principles introduced here can therefore aid in both screening and suggesting novel design strategies for maximizing conductance tunability in single-molecule systems.
Nathan D. Bamberger, Jeffrey A. Ivie, Keshaba N. Parida, Dominic V. McGrath, and Oliver L. A. Monti
American Chemical Society (ACS)
Tarek H. El-Assaad, Keshaba N. Parida, Marcello F. Cesario, and Dominic V. McGrath
Royal Society of Chemistry (RSC)
A new metal-free ortho oxidation of 2,7-di-tert-butylpyrene provides in high yield the corresponding 4,5-dione and 4,5,9,10-tetraone in environmentally benign solvents.
Nathan D. Bamberger, Jeffrey A. Ivie, Keshaba N. Parida, Dominic V. McGrath, and Oliver L. A. Monti
American Chemical Society (ACS)
Improved understanding of charge-transport in single molecules is essential for harnessing the potential of molecules, e.g., as circuit components at the ultimate size limit. However, interpretatio...
Shlomy Arava, Shimon Maksymenko, Keshaba Nanda Parida, Gulab K. Pathe, Atul M. More, Yuriy B. Lipisa, and Alex M. Szpilman
MyJove Corporation
α-Functionalization of ketones via umpolung of enolates by hypervalent iodine reagents is an important concept in synthetic organic chemistry. Recently, we have developed a two-step strategy for ketone enolate umpolung that has enabled the development of methods for chlorination, azidation, and amination using azoles. In addition, we have developed C-C bond-forming arylation and allylation reactions. At the heart of these methods is the preparation of the intermediate and highly reactive enolonium species prior to addition of a reactive nucleophile. This strategy is thus reminiscent of the preparation and use of metal enolates in classical synthetic chemistry. This strategy allows the use of nucleophiles that would otherwise be incompatible with the strongly oxidizing hypervalent iodine reagents. In this paper we present a detailed protocol for chlorination, azidation, N-heteroarylation, arylation, and allylation. The products include motifs prevalent in medicinally active products. This article will greatly assist others in using these methods.
Keshaba N Parida, Gulab K Pathe, Shimon Maksymenko, and Alex M Szpilman
Beilstein Institut
Due to their closely matched reactivity, the coupling of two dissimilar ketone enolates to form a 1,4-diketone remains a challenge in organic synthesis. We herein report that umpolung of a ketone trimethylsilyl enol ether (1 equiv) to form a discrete enolonium species, followed by addition of as little as 1.2–1.4 equivalents of a second trimethylsilyl enol ether, provides an attractive solution to this problem. A wide array of enolates may be used to form the 1,4-diketone products in 38 to 74% yield. Due to the use of two TMS enol ethers as precursors, an optimization of the cross-coupling should include investigating the order of addition.
Atul A. More, Gulab K. Pathe, Keshaba N. Parida, Shimon Maksymenko, Yuriy B. Lipisa, and Alex M. Szpilman
American Chemical Society (ACS)
Enolonium species, resulting from the umpolung of ketone enolates by Koser's hypervalent iodine reagents activated by boron trifluoride, react with a variety of nitrogen heterocycles to form α-aminated ketones. The reactions are mild and complete in 4-5 h. Additionally, α-azidation of the enolonium species takes place using trimethylsilyl azide as a convenient source of azide nucleophile.
Shimon Maksymenko, Keshaba N. Parida, Gulab K. Pathe, Atul A. More, Yuriy B. Lipisa, and Alex M. Szpilman
American Chemical Society (ACS)
Herein it is shown, for the first time, that enolonium species are powerful electrophiles capable of reacting with aromatic compounds in an intermolecular manner to afford α-arylated ketones. The reaction is compatible with a variety of functional groups, is of wide scope with respect to aromatic compounds and ketone, and even works for polymerization-prone substrates such as substituted pyrroles, thiophenes, and furans. Only 1.6 to 5 equiv of the commodity aromatic substrates is needed.
Shlomy Arava, Jayprakash N. Kumar, Shimon Maksymenko, Mark A. Iron, Keshaba N. Parida, Peter Fristrup, and Alex M. Szpilman
Wiley
Enolonium species/iodo(III)enolates of carbonyl compounds have been suggested to be intermediates in a wide variety of hypervalent iodine induced chemical transformations of ketones, including α-C-O, α-C-N, α-C-C, and α-carbon-halide bond formation, but they have never been characterized. We report that these elusive umpoled enolates may be made as discrete species that are stable for several minutes at -78 °C, and report the first spectroscopic identification of such species. It is shown that enolonium species are direct intermediates in C-O, C-N, C-Cl, and C-C bond forming reactions. Our results open up chemical space for designing a variety of new transformations. We showcase the ability of enolonium species to react with prenyl, crotyl, cinnamyl, and allyl silanes with absolute regioselectivity in up to 92 % yield.
Shradhey Gupta, Keshaba Nanda Parida, Puspal Mukherjee, and Pratik Sen
Springer Science and Business Media LLC
Abstract
The present study elucidates the synergetic solvation behavior of t-butanol–dichloromethane (t-BuOH–DCM) binary solvent mixtures. UV–visible absorption, emission and 1H-NMR spectroscopy along with analytical modelling were used to ascertain the nature of interactions present, which are found to be maximum at Xt-BuOH = 0.40, leading to a super solvation environment. The increased polarity of the t-BuOH–DCM binary solvent mixtures through interactive solvent association is believed provide a unique reaction medium that can alter the fate of chemical processes involving a polar species. This idea has been demonstrated by the transformation of merocyanine to 1′,3′-dihydro-,1′,3′,3′-trimethyl-6-nitropiro[2H-1-benzopyran-2,2′-(2H)-indole] and the oxidation of cholestanol to cholestanone.
Ajeet Chandra, Keshaba Nanda Parida, and Jarugu Narasimha Moorthy
Elsevier BV
Abstract Simple one-pot protocols for the syntheses of α-bromoketones and α-azidoketones starting from olefins have been developed by employing catalytic oxidation of the intermediary bromohydrins with in situ-generated modified IBX as the key reaction. The improved procedure involves initial formation of bromohydrin by the reaction of olefin with NBS in acetonitrile-water mixture (1:1) at rt followed by oxidation with in situ-generated 3,4,5,6-tetramethyl-2-iodoxybenzoic acid (TetMe-IBX), produced in catalytic amounts from 3,4,5,6-tetramethyl-2-iodobenzoic and Oxone. α-Bromoketones are further converted in the same pot to the corresponding α-azidoketones using NaN3/NaHCO3. The one-pot conversions are versatile for a variety of olefins that include cyclic as well as acyclic aliphatic olefins and electron-rich and electron-deficient styrenes. Chemoselective bromohydroxylation of electron-rich double bond and subsequent oxidation to the α-bromoketone is demonstrated for a substrate that contains both electron-rich and deficient double bonds.
Keshaba Nanda Parida, Ajeet Chandra, and Jarugu Narasimha Moorthy
Wiley
The reagent system Oxone®/NaHCO3 is shown to be very convenient for direct conversion of thiols to sulfonic acids. The simple procedure that involves stirring of thiol, Oxone®/NaHCO3 in CH3CN-H2O (3:2, v/v) mixture at 20±5 °C allows access to a variety of aliphatic as well as electron rich and deficient aromatic sulfonic acids. The oxidation is also shown to occur with KBrO3, albeit over longer durations. The mechanism of thiol-to-sulfonic acid oxidation with Oxone® is proposed to proceed via electron transfer steps, which is supported by the formation of disufide at low conversions.
Keshaba Nanda Parida and Jarugu Narasimha Moorthy
American Chemical Society (ACS)
A simple procedure for the synthesis of a variety of o-carboxyarylacrylic acids has been developed with Oxone (2KHSO5·KHSO4·K2SO4); the oxidation reaction involves the stirring of methoxy/hydroxy-substituted naphthalenes, phenanthrenes, anthracenes, etc. with Oxone in an acetonitrile-water mixture (1:1, v/v) at rt. Mechanistically, the reaction proceeds via initial oxidation of naphthalene to o-quinone, which undergoes cleavage to the corresponding o-carboxyarylacrylic acid. The higher aromatics are found to yield carboxymethyl lactones derived from the initially formed o-carboxyarylacrylic acids.
Jarugu Narasimha Moorthy and Keshaba Nanda Parida
American Chemical Society (ACS)
Oxidative cleavage of a variety of olefins to the corresponding ketones/carboxylic acids is shown to occur in a facile manner with 3,4,5,6-tetramethyl-2-iodobenzoic acid (TetMe-IA)/oxone. The simple methodology involves mere stirring of the olefin and catalytic amount (10 mol %) of TetMe-IA and oxone in acetonitrile-water mixture (1:1, v/v) at rt. The reaction mechanism involves initial dihydroxylation of the olefin with oxone, oxidative cleavage by the in situ-generated 3,4,5,6-tetramethyl-2-iodoxybenzoic acid (TetMe-IBX), and oxidation of the aldehyde functionality to the corresponding acid with oxone. Differences in the reactivities of electron-rich and electron-poor double bonds have been exploited to demonstrate chemoselective oxidative cleavage in substrates containing two double bonds.
Keshaba Nanda Parida and Jarugu Narasimha Moorthy
Elsevier BV
A variety of olefins is shown to be cleaved oxidatively to the corresponding acids with oxone as the reagent. The simple methodology that works well for a range of alkenes, i.e., styrenes, nitrostyrenes, stilbenes, cinnamic acids, chalcones, etc., involves heating of the reactant with oxone in acetonitrile–water mixture (1:1, v/v) at reflux. The oxidation cascade involves initial dihydroxylation followed by oxidative cleavage and oxidation of the resultant aldehydes to acids.