A5000779109- Crystallography and molecular interactions
- Advanced Chemical Physics Studies
- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Molecular Spectroscopy and Structure
- Protein Structure and Dynamics
- Ionic liquids properties and applications
- Photochemistry and Electron Transfer Studies
- Electrochemical sensors and biosensors
- Porphyrin and Phthalocyanine Chemistry
- Spectroscopy and Quantum Chemical Studies
- Free Radicals and Antioxidants
- Chemical Synthesis and Analysis
- Metal complexes synthesis and properties
- Mass Spectrometry Techniques and Applications
- Multicomponent Synthesis of Heterocycles
- Molecular spectroscopy and chirality
- Chemical Synthesis and Reactions
- Photodynamic Therapy Research Studies
- Electrochemical Analysis and Applications
- Enzyme Structure and Function
- Nanoplatforms for cancer theranostics
- Metal-Catalyzed Oxygenation Mechanisms
- Chemical and Physical Properties in Aqueous Solutions
- Photoreceptor and optogenetics research
National Institute of Science Education and Research
2016-2025
Homi Bhabha National Institute
2016-2025
Indian Institute of Science Education and Research Berhampur
2024
Institute of Physics, Bhubaneshwar
2012-2016
Czech Academy of Sciences, Institute of Physics
2014-2016
Laboratoire Francis Perrin
2010-2014
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2010-2012
Centre National de la Recherche Scientifique
2010-2012
Institut Rayonnement-Matière de Saclay
2011-2012
CEA Paris-Saclay
2011-2012
The N−H···S hydrogen-bonded complexes of the model compounds tryptophan (indole and 3-methylindole) methionine (dimethyl sulfide, Me2S) have been characterized by a combination experimental techniques like resonant two-photon ionization (R2PI), ion dip infrared spectroscopy (RIDIRS), fluorescence (FDIRS) computational methods ab initio electronic structure calculations, atoms-in-molecules (AIM), natural bond orbital (NBO), energy decomposition analyses. results are compared with N−H···O...
We report hydrogen-bonded complexes of H(2)S with indole and 3-methyl stabilized by the S-H...pi interaction. It is interesting to discover that although sulfur its hydrides are known as poor hydrogen-bond donor/acceptors, not too far behind oxygen, nitrogen, carbon in regard forming pi-type hydrogen bonds. This also extends scope our earlier studies from sigma-type (O-H...S N-H...S complexes) (S-H...pi complexes). The experiments were carried out using supersonic jet expansion technique,...
ConspectusHydrogen bonds (H-bonds) play important roles in imparting functionality to the basic molecules of life by stabilizing their structures and directing interactions. Numerous studies have been devoted understanding H-bonds involving highly electronegative atoms like nitrogen, oxygen, halogens consequences those chemical reactions, catalysis, structure function biomolecules; but involvement less sulfur selenium H-bond formation establishes concept noncanonical H-bonds. Initially...
Carbon bonds (C-bonds) are the highly directional noncovalent interactions between carbonyl-oxygen acceptors and sp3 -hybridized-carbon σ-hole donors through n→σ* electron delocalization. We have shown ubiquitous existence of C-bonds in proteins with help careful protein structure analysis quantum calculations, precisely determined C-bond energies. The importance conventional such as hydrogen bond (H-bonds) halogen (X-bonds) function biological molecules well established, while carbon still...
Gas-phase vibrational spectroscopy, coupled cluster (CCSD(T)), and dispersion corrected density functional (B97-D3) methods are employed to characterize surprisingly strong sulfur center H-bonded (SCHB) complexes between cis trans amide NH S atom of methionine cysteine side chain. The N-H···S H-bonds compared with the representative classical σ- π-type such as N-H···O, N-H···O═C N-H···π H-bonds. With spectroscopic, theoretical, structural evidence, found be σ-type H-bonds, despite smaller...
Presently, there are no approved drugs or vaccines to treat COVID-19 which has spread over 200 countries and is responsible for 3,65,000 deaths worldwide. Recent studies have shown that two human proteases, TMPRSS2 cathepsin L, play a key role in host cell entry of SARS-CoV-2. Importantly, inhibitors these proteases were block SARS-CoV-2 infection. Here, we perform virtual screening 14010 phytochemicals produced by Indian medicinal plants identify natural product L. We built homology model...
The weak hydrogen bonding ability of sulfur-containing hydrides makes it difficult to study their complexes and has not been characterized experimentally so far. In this work, the hydrogen-bonded H(2)S H(2)O with p-cresol (p-CR) were studied using a variety techniques such as two-color resonant two-photon ionization (2c-R2PI) spectroscopy, single vibronic level fluorescence (SVLF) resonance ion dip infrared spectroscopy (RIDIRS), (FDIRS), an aim comparing nature strength respective...
Despite of being ubiquitous in proteins, NHbackbone···S hydrogen bonds linking the sulfur atom methionine or cysteine to backbone NH groups remain poorly documented. Here, we report vibrationally resolved IR stretch spectra two methionine-containing dipeptides (Ac-Phe-Met-NH2 and Ac-Met-Phe-NH2). The conformations observed for both molecules, assigned with help DFT-D quantum chemistry, provide spectroscopic evidence formation H-bonds, surprisingly strong enough challenge classical...
The importance of Sulfur centred hydrogen bonds (SCHBs) cannot be underestimated given the current day knowledge its non-covalent interactions prevalent in many biopolymers as well organic systems. Based on distance/angle constraints available from structural database, these have been interchangeably termed van der Waals/hydrogen bonded complexes. There is a lack sufficient spectroscopic evidence that can unequivocally term bonding interactions. In this review we present laser investigations...
In order to assess the ability of theory describe properly dispersive interactions that are ubiquitous in peptide and protein systems, an isolated short chain has been studied using both gas-phase laser spectroscopy quantum chemistry. The experimentally observed coexistence extended form a folded supersonic expansion was found result from comparable Gibbs free energies for two species under high-temperature conditions (≤320 K) resulting desorption technique used vaporize molecules. These...
In this paper, the effect of alkyl substitution at hydrogen bond acceptor and its chain length on strength nature bonding is presented. present study we combine both experimental computational methods to investigate characteristics O-H...O O-H...S in complexes p-cresol (p-CR) with methanol (MeOH), ethanol (EtOH), methanethiol (MeSH), ethanethiol (EtSH). The results indicate that, an increase length, become stronger. Energy decomposition analysis emphasizes dispersive bonding. addition, it...
The mechanisms of nonradiative deactivation a phenylalanine residue after near-UV photoexcitation have been investigated in an isolated peptide chain model (N-acetylphenylalaninylamide, NAPA) both experimentally and theoretically. Lifetime measurements at the origin first ππ* state jet-cooled NAPA molecules shown that (i) among three most stable conformers molecule, folded conformer B is ∼50-times shorter lived than extended major A (ii) this lifetime virtually insensitive to deuteration...
The formation of monohydrates capped phenylalanine model peptides, CH3-CO-Phe-NH2 and CH3-CO-Phe-NH-CH3, in a supersonic expansion has been investigated using laser spectroscopy quantum chemistry methods. Conformational distributions the have revealed by IR/UV double-resonance their structures assigned comparison with DFT-D calculations. A careful analysis final hydrate distribution together detailed theoretical investigation potential energy surface demonstrates that solvation occurs from...
Careful protein structure analysis unravels many unknown and unappreciated noncovalent interactions that control structure; one such unrecognized interaction in is selenium centered hydrogen bonds (SeCHBs). We report, for the first time, SeCHBs involving amide proton of selenomethionine (Mse), i.e., amide–N–H···Se H-bonds discerned proteins. Using mass selective conformer specific high resolution vibrational spectroscopy, gold standard quantum chemical calculations at CCSD(T), in-depth...
Thioamides are used as potential surrogates of amides to study the structure and dynamics proteins nucleic acids. However, incorporation thioamides in biomolecules leads changes their structures conformations mostly attributed strength amide-N-H···S═C hydrogen bond. In most cases, it is considered weak owing small electronegativity sulfur, some strong conventional H-bonds. Herein, adopting PDB analysis, NMR spectroscopy, quantum chemistry calculations, we have shown that a geometrical...
Long-term storage and stability of DNA is paramount importance in biomedical applications. Ever since the emergence ionic liquids (ILs) as alternate green solvents to aqueous organic solvents, their exploration for extraction application need conscientious understanding binding characteristics molecular interactions between IL DNA. Choline amino acid ILs (CAAILs) this regard seem be promising due non-cytotoxic, completely biobased environment-friendly nature. To unravel key factors strength...
The demand for long-term storage and stability of proteins has increased substantially in the pharmaceutical industries, yet sensitivity toward environment become a cardinal task researchers. To deal with this, we have selected multifunctional enzyme Cytochrome-c (Cyt-c) involved many chemical biochemical reactions as model protein, which is very sensitive loses structural integrity on exposure to environment. remarkable features ionic liquids (ILs) entitled them alternatives aqueous organic...
The importance of selenium-centered noncovalent chalcogen bonds represented as Se⋅⋅⋅A (A=O/S) has been explored for short directional contacts in small molecules and proteins. In addition, S⋅⋅⋅O centered have analyzed. Computational analyses involving the quantitative assessment associated energetics, molecular electrostatic potentials (MEP), electron density derived topological parameters, namely, quantum theory atom (QTAIM) analyses, NBO (natural bond orbital) based calculations, performed...
Hydrogen bonding (H-bonding) without lone pair(s) of electrons and π-electrons is a concept developed 2–3 years ago. H-bonds involving less electronegative tetrahedral carbon are beyond the classical H-bonds. Herein, we present first report on with tetravalent carbons in proteins. A special arrangement needed to increase negative charge density around sp3-hybridized atom. Therefore, elements such as As Mg, when bonded sp3-C, enable C-atoms H-bond acceptors. Careful protein structure analysis...
The Psoralen (Pso) molecule finds extensive applications in photo-chemotherapy, courtesy of its triplet state forming ability. Sulfur and selenium replacement exocyclic carbonyl oxygen organic chromophores foster efficient harvesting with near unity quantum yield. These triplet-forming photosensitizers are useful Photodynamic Therapy (PDT) for selective apoptosis cancer cells. In this work, we have critically assessed the effect sulfur substitution at (TPso SePso, respectively) endocyclic...
In this work the hydrogen bonded complexes of diethyl ether (DEE) and sulfide (DES) with p-cresol (p-CR) were investigated. Only one conformer p-CR.DEE complex three conformers p-CR.DES found to be present under supersonic jet expansion conditions. The conformational assignments done help IR-UV double resonance studies ab initio calculations. red shifts in OH stretching frequency for O-H...O O-H...S quite close each other. fact, showed a slightly larger shift stretch than that conformer,...