The Role of Anharmonicity in the HC*D Chromophore in Vibrational Circular Dichroism Spectra and Optical Rotation Data

Year: 2025

Authors: Fusi M., Longhi G., Mazzeo G., Bloino J., Abbate S.

Autors Affiliation: Univ Brescia, Dipartimento Med Mol & Traslaz, I-25123 Brescia, Italy; Scuola Normale Super Pisa, I-56125 Pisa, Italy; CNR, Ist Nazl Ottica INO, Res Unit Brescia, CSMT, I-25123 Brescia, Italy.

Abstract: The vibrational circular dichroism (VCD) spectra in the CD-stretching region of (R)-(-)-neopentyl-1d-halides (Cl and Br), (R)-(+)-1-exo-d1-camphor, and (S)-(+)-1-phenylethane-1-d1 (and (S)-(+)-1-phenylethane-1,2,2,2-d4) are correctly interpreted by properly including anharmonicity, both mechanical and electrical, with DFT calculations. This result is noteworthy, since the spectroscopic range containing the CD-stretching transitions is always rich in features attributed to overtone and combination transitions. The importance of the reported simulations is thought to go beyond the cases discussed here and to be applicable to other molecules containing the HC*D fragment and, more generally, CD, a point that is rising in importance after the FDA’s approval of deuterated drugs. Furthermore, proper treatment of anharmonicity helps in the interpretation of other observables, like e.g., specific optical rotations (OR).

Journal/Review: JOURNAL OF PHYSICAL CHEMISTRY A

Volume: 129 (29)      Pages from: 6615  to: 6622

More Information: Funding was provided by the Italian Ministry of University and Research (MUR) through the PRIN 2022 and PRIN 2020 programs: project Enhancing Circularly Polarised Emitters Quantum Efficiency Exploiting Singlet-Triplet Inversion (INVESTCPE), prot. 2022CXHY3A; project Smart [n]heterohelicenes: enantioselective synthesis, circularly polarized luminescence, redox switching, and functionalized polymers (SMART HELIX), prot. 2022B3EFJH; and project Photoreactive Systems upon Irradiation: Modelling and Observation of Vibrational Interactions with the Environment (PSI-MOVIE), prot. 2020HTSXMA). The Big & Open Data Innovation Laboratory (BODaI-Lab) of the University of Brescia is acknowledged for providing access to CINECA high-performance computing facilities. The CINECA award under the ISCRA C (CCESTI – HP10CPAAXL) initiative is also acknowledged.
KeyWords: Absolute-configuration; Displacement-reactions; Carbon-hydrogen; Vcd Spectra; Density; Assignment; Ir
DOI: 10.1021/acs.jpca.5c03064