Solvent Effects and Aggregation Phenomena Studied by Vibrational Optical Activity and Molecular Dynamics: The Case of Pantolactone

Year: 2020

Authors: Ghidinelli S., Abbate S., Koshoubu J., Wada T., Longhi G.

Autors Affiliation: Univ Brescia, Dipartimento Med Mol & Traslazionale, I-25123 Brescia, Italy; CNR, Res Unit Brescia, Ist Nazl Ott INO, I-25123 Brescia, Italy; JASCO Corp, Hachioji, Tokyo 1928537, Japan; Tohoku Univ, Inst Multidisciplinary Res Adv Mat, Sendai, Miyagi 9808577, Japan.

Abstract: Raman and Raman optical activity (ROA), IR, and vibrational circular dichroism (VCD) spectra of (R)- and (S)-pantolactone have been recorded in three solvents. ROA has been employed on water and DMSO solutions, VCD on DMSO and CCl(4 )solutions. In the last solvent, monomer-dimer equilibrium is present. Due to the low conformational flexibility of the isolated molecule and to the possibility of aggregation, this compound has been used here to test different protocols for computation of the spectroscopic responses taking into account solvent effects. Molecular dynamics (MD) simulations have been carried out together with statistical clustering methods based on collective variables to extract the structures needed to calculate the spectra. Quantum mechanical DFT calculations based on PCM are compared with approaches based on different representations of the solvent shell (MM or QM level). Appropriate treatment of the solvent permits obtaining of good band-shapes, with the added advantage that the MD analysis allows one to take into account flexibility of dimeric structures justifying the broadness of observed bands and the absence of intense VCD couplets in the carbonyl and OH stretching regions.

Journal/Review: JOURNAL OF PHYSICAL CHEMISTRY B

Volume: 124 (22)      Pages from: 4512  to: 4526

More Information: We acknowledge the use of CINECA facilities at Bologna, Italy: ISCRA Grants “IsC63_SELFASS” and “IsC Pan-3SOL”. Support from the Italian MIUR (PRIN 2017, Project “Physicochemical Heuristic Approaches: Nanoscale Theory Of Molecular Spectroscopy” (PHANTOMS), pr o t. 2017A4XRCA) is acknowledged. Also, support in part by a Grant-in-Aid for a Network Joint Research Center for Materials and Devices of Japan is acknowledged.
KeyWords: CIRCULAR-DICHROISM; CONFORMATIONAL-ANALYSIS; RAMAN; SPECTRA; RING; SIMULATION; CHIRALITY; SET
DOI: 10.1021/acs.jpcb.0c01483

Citations: 26
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