01875nas a2200193 4500008004100000022001400041245009900055210006900154260007100223300001400294490000600308520115000314100001801464700002401482700001601506700001801522700001801540856012301558 2016 eng d a1948-718500aPick and choose the spectroscopic method to calibrate the local electric field inside proteins0 aPick and choose the spectroscopic method to calibrate the local  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcJUL a2456-24600 v73 a

Electrostatic interactions in proteins play a crucial role in determining the structure function relation in biomolecules. In recent years, fluorescent probes have been extensively employed to interrogate the polarity in biological cavities through dielectric constants or semiempirical polarity scales. A choice of multiple spectroscopic methods, not limited by fluorophores, along with a molecular level description of electrostatics involving solute-solvent interactions, would allow more flexibility to pick and choose the experimental technique to determine the local electrostatics within protein interiors. In this work we report that ultraviolet/visible-absorption, infrared-absorption, or C-13 NMR can be used to calibrate the local electric field in both hydrogen bonded and non-hydrogen bonded protein environments. The local electric field at the binding site of a serum protein has been determined using the absorption wavelength as well as the carbonyl stretching frequency of its natural steroid substrate, testosterone. Excellent agreement is observed in the results obtained from two independent spectroscopic techniques.

1 aHaldar, Tapas1 aKashid, Somnath, M.1 aDeb, Pranab1 aKesh, Sandeep1 aBagchi, Sayan uhttps://library.ncl.res.in/content/pick-and-choose-spectroscopic-method-calibrate-local-electric-field-inside-proteins02230nas a2200193 4500008004100000022001400041245009700055210006900152260000900221300001600230490000600246520156000252100002101812700002501833700001801858700001801876700001701894856012501911 2022 eng d a2470-134300aPredicting the redox potentials of phenazine derivatives using DFT-assisted machine learning0 aPredicting the redox potentials of phenazine derivatives using D cAPR  a11742-117550 v73 a

This study investigates four machine-learning (ML) models to predict the redox potentials of phenazine derivatives in dimethoxyethane using density functional theory (DFT). A small data set of 151 phenazine derivatives having only one type of functional group per molecule (20 unique groups) was used for the training. Prediction accuracy was improved by a combined strategy of feature selection and hyperparameter optimization, using the external validation set. Models were evaluated on the external test set containing new functional groups and diverse molecular structures. High prediction accuracies of R2 > 0.74 were obtained on the external test set. Despite being trained on the molecules with a single type of functional group, models were able to predict the redox potentials of derivatives containing multiple and different types of functional groups with good accuracies (R2 > 0.7). This type of performance for predicting redox potential from such a small and simple data set of phenazine derivatives has never been reported before. Redox flow batteries (RFBs) are emerging as promising candidates for energy storage systems. However, new green and efficient materials are required for their widespread usage. We believe that the hybrid DFT-ML approach demonstrated in this report would help in accelerating the virtual screening of phenazine derivatives, thus saving computational and experimental costs. Using this approach, we have identified promising phenazine derivatives for green energy storage systems such as RFBs.

1 aGhule, Siddharth1 aDash, Soumya, Ranjan1 aBagchi, Sayan1 aJoshi, Kavita1 aVanka, Kumar uhttps://library.ncl.res.in/content/predicting-redox-potentials-phenazine-derivatives-using-dft-assisted-machine-learning01775nas a2200217 4500008004100000022001400041245010100055210006900156260000800225300001400233490000800247520102800255100001901283700002701302700002901329700002701358700001801385700001801403700001601421856012001437 2024 eng d a1520-610600aPerturbation of fermi resonance on hydrogen-bonded > C=O: 2D IR studies of small ester probes0 aPerturbation of fermi resonance on hydrogenbonded gt CO 2D IR st cAPR a4440-44470 v1283 a

We utilized linear and 2D infrared spectroscopy to analyze the carbonyl stretching modes of small esters in different solvents. Particularly noteworthy were the distinct carbonyl spectral line shapes in aqueous solutions, prompting our investigation of the underlying factors responsible for these differences. Through our experimental and theoretical calculations, we identified the presence of the hydrogen-bond-induced Fermi resonance as the primary contributor to the varied line shapes of small esters in aqueous solutions. Furthermore, our findings revealed that the skeletal deformation mode plays a crucial role in the Fermi resonance for all small esters. Specifically, the first overtone band of the skeletal deformation mode intensifies when hydrogen bonds form with the carbonyl group of esters, whereas such coupling is rare in aprotic organic solvents. These spectral insights carry significant implications for the utilization of esters as infrared probes in both biological and chemical systems.

1 aSakpal, Sushil1 aChakrabarty, Suranjana1 aReddy, Kambham, Devendra1 aDeshmukh, Samadhan, H.1 aBiswas, Rajib1 aBagchi, Sayan1 aGhosh, Anup uhttps://library.ncl.res.in/content/perturbation-fermi-resonance-hydrogen-bonded-co-2d-ir-studies-small-ester-probes00759nas a2200229 4500008004100000022001400041245007900055210006900134260000900203300001600212490000700228653002700235653002400262653001500286100002700301700001800328700002100346700002000367700001800387700001800405856010600423 2024 eng d a2040-336400aProbing surface interactions in CdSe quantum dots with thiocyanate ligands0 aProbing surface interactions in CdSe quantum dots with thiocyana cAUG  a14922-149310 v1610aCOLLOIDAL NANOCRYSTALS10aSTRUCTURAL DYNAMICS10aThin-films1 aDeshmukh, Samadhan, H.1 aYadav, Sushma1 aChowdhury, Tubai1 aPathania, Akhil1 aSapra, Sameer1 aBagchi, Sayan uhttps://library.ncl.res.in/content/probing-surface-interactions-cdse-quantum-dots-thiocyanate-ligands01901nas a2200181 4500008004100000022001400041245011500055210006900170260000800239300001100247490000800258520123800266100002101504700002001525700002601545700001801571856013001589 2025 eng d a0021-960600aProbing solvent fluctuations in deep eutectic solvents: Influence of probe charge and nano-domain localization0 aProbing solvent fluctuations in deep eutectic solvents Influence cJUL a0445060 v1633 a

Deep eutectic solvents (DESs) segregate into hydrogen bond acceptor or hydrogen bond donor (HBD) rich nano-domains, leading to molecular heterogeneity. Understanding how this heterogeneity affects the DES structure and dynamics is essential. In this study, we used two-dimensional nuclear magnetic resonance (2D NMR) and two dimensional infrared (2D IR) spectroscopies, combined with molecular dynamics (MD) simulations, to investigate solvation structure and dynamics in two choline chloride-based DESs with different HBDs-levulinic acid and glycolic acid. We introduced two thiocyanate vibrational probes, methyl thiocyanate (CH3SCN, neutral) and ammonium thiocyanate (NH4SCN, anionic), which selectively localize in specific nano-domains. 2D NMR provided insights into solvent structure and probe location, while 2D IR captured solvation dynamics. Our results show that these small probes do not alter the solvent structure, regardless of charge. However, solvation dynamics depend on long-range electrostatic ordering in the DES and the local shielding effects of the nano-domain where the probe resides. MD simulations complement experimental findings, providing a molecular-level understanding of solvation in DESs.

1 aChowdhury, Tubai1 aPathania, Akhil1 aRavindranathan, Sapna1 aBagchi, Sayan uhttps://library.ncl.res.in/content/probing-solvent-fluctuations-deep-eutectic-solvents-influence-probe-charge-and-nano-domain