@article {47744, title = {Stabilization of Azapeptides by N-amide center dot center dot center dot H-N-amide Hydrogen Bonds}, journal = {Organic Letters}, volume = {23}, year = {2021}, month = {JUL }, pages = {4949-4954}, type = {Article}, abstract = {An unusual N-amide center dot center dot center dot H-Namide hydrogen bond (HB) was previously proposed to stabilize the azapeptide beta-turns. Herein we provide experimental evidence for the N-amide center dot center dot center dot H-Namide HB and show that this HB endows a stabilization of 1-3 kcal.mol(-1) and enforces the trans-cis-trans (t-c-t) and cis-cis-trans (c-c-t) amide bond conformations in azapeptides and N-methyl-azapeptides, respectively. Our results indicate that these N-amide center dot center dot center dot H-Namide HBs can have stabilizing contributions even in short azapeptides that cannot fold to form beta-turns.}, issn = {1523-7060}, doi = {10.1021/acs.orglett.1c01111}, author = {Baruah, Kalpita and Sahariah, Biswajit and Sakpal, Sushil S. and Deka, Jugal Kishore Rai and Bar, Arun Kumar and Bagchi, Sayan and Sarma, Bani Kanta} } @article {48831, title = {Solvation structure and dynamics of a small ion in an organic electrolyte}, journal = {Journal of Photochemistry and Photobiology A-Chemistry}, volume = {440}, year = {2023}, month = {JUN}, pages = {114666}, type = {Article}, abstract = {

Organic carbonates are commonly used as electrolytes in commercial lithium-ion batteries. A detailed interpretation of the solvation structure and dynamics of the electrolyte around ions is necessary to understand the charge/discharge process in batteries. This work combines infrared absorption spectroscopy with quantum chemical calculations and molecular dynamics simulations to decipher the solvation structure of propylene carbonate, a cyclic carbonate, around the dissolved thiocyanate ion. Two dimensional infrared spectroscopy and polarization-selective pump probe spectroscopies have been utilized to extract the timescales of solvent fluctuation and the solute reorientational dynamics. The similarity in the slow timescales for the solute and the solvent dynamics signifies that similar processes control both dynamics.

}, issn = {1010-6030}, doi = {10.1016/j.jphotochem.2023.114666}, author = {Kore, Shivshankar and Sahoo, Rudhi Ranjan and Santra, Binit and Sarkar, Archishman and Chowdhury, Tubai and Deshmukh, Samadhan H. and Hazarika, Sulagna and Chatterjee, Srijan and Bagchi, Sayan} } @article {49415, title = {Slowdown of solvent structural dynamics in aqueous DMF solutions}, journal = {Chemical Physics Impact}, volume = {9}, year = {2024}, month = {DEC}, abstract = {

This study presents a comprehensive investigation into the molecular dynamics of solvation environments through an integrated approach combining Fourier-transform infrared (FTIR) spectroscopy, molecular dynamics (MD) simulations, and two-dimensional infrared (2D IR) spectroscopy. We explore the solvation of an ionic solute (ammonium thiocyanate) in various solvent systems, including N,N-dimethylformamide (DMF), water, and a 0.5 mole fraction of DMF in water, aiming to unravel the intricate interplay between solute-solvent interactions and solvent dynamics across diverse solvation environments. By integrating FTIR spectral analysis with radial distribution functions and coordination numbers obtained from MD simulations, we decipher the solvent composition around the solute molecule. Analysis of 2D IR spectra and hydrogen bond, as well as dipolar autocorrelation function from MD simulations, further elucidates the nuances of solute-solvent interactions, highlighting the impact of solvent dynamics on solvation structures. Our results reveal a significant slowdown of the solvent structural dynamics in the equimolar binary solvent mixture compared to the neat solvents. This slowdown underscores the complex relationship between solute-solvent interactions and solvent dynamics. The integration of FTIR, MD simulations, and 2D IR spectroscopy provides a unified framework for obtaining a holistic understanding of solvation dynamics, offering valuable insights into the underlying molecular mechanisms governing solute-solvent interactions in complex systems. These results pave the way for future studies to delve deeper into the molecular intricacies of solvation phenomena.

}, doi = {https://doi.org/10.1016/j.chphi.2024.100711}, author = {Pathania, Akhil and Bagchi, Sayan} } @article {49184, title = {Solvation dynamics and microheterogeneity in deep eutectic solvents}, journal = {Journal of Physical Chemistry B}, volume = {128}, year = {2024}, month = {DEC}, pages = {12669-12684}, type = {Review}, abstract = {

Deep eutectic solvents have attracted considerable attention due to their unique properties and their potential to replace conventional solvents in diverse applications, such as catalysis, energy storage, and green chemistry. However, despite their broad use, the microscopic mechanisms governing solvation dynamics and the role of hydrogen bonding in deep eutectic solvents remain insufficiently understood. In this article, we present our contributions toward unravelling the micro heterogeneity within deep eutectic solvents by combining vibrational Stark spectroscopy and two-dimensional infrared spectroscopy with molecular dynamics simulations. Our findings demonstrate how the composition, constituents, and addition of water significantly influence the heterogeneous hydrogen bonding network and solvent dynamics within these systems. These insights provide valuable guidance for the design of next-generation solvents tailored to specific applications. By integrating experimental and computational approaches, this work sheds light on the intricate relationship between solvation dynamics and nanostructure in deep eutectic solvents, ultimately paving the way for innovative advances in solvent design.

}, issn = {1520-6106}, doi = {10.1021/acs.jpcb.4c06295}, author = {Chatterjee, Srijan and Chowdhury, Tubai and Bagchi, Sayan} }