Scientific Results

Testing the vibrational exciton and the local mode models on the instructive cases of dicarvone, dipinocarvone, and dimenthol vibrational circular dichroism spectra

Year: 2020

Authors: Mazzeo G., Santoro E., Abbate S., Zonta C., Fabris F., Longhi G.

Autors Affiliation: Univ Brescia, Dipartimento Med Mol & Traslaz, Viale Europa 11, Brescia 25123, Italy; CNR, Ist Nazl Ott INO, Res Unit Brescia, Brescia, Italy;‎ Univ Padua, Dipartimento Sci Chim, Padua, Italy;‎ Univ Ca Foscari Venezia, Dipartimento Sci Mol & Nanosistemi, Venice, Italy

Abstract: The vibrational circular dichroism (VCD) spectra of dicarvone (1), dipinocarvone (2), and dimenthol (3) have been recorded in the range 900-3200 cm(-1), encompassing the mid-infrared (mid-IR), the C(sic)O stretching, and the CH-stretching regions. For compound 3 also, the fundamental and the first overtone OH stretching regions have been investigated by IR/NIR absorption and VCD. Density functional theory (DFT) calculations allow one to interpret the IR and VCD spectra and to confirm the configuration/conformational studies previously conducted by X-ray diffraction. The most intense VCD signals are associated with the vibrational normal modes involving symmetry-related groups close to the CC bond connecting covalently the two molecular units. The vibrational exciton (VCDEC) model is fruitfully tested on the VCD data of compounds 1 and 2 for the spectroscopic regions at similar to 1700 cm(-1), and the local mode model is tested on compound 3 at similar to 3500 and similar to 6500 cm(-1). For compounds 1 and 2 also, ECD spectra are reported, and the exciton mechanism is tested also there, and connections to the VCDEC model are examined.

Journal/Review: CHIRALITY

Volume: 32 (7)      Pages from: 907  to: 921

KeyWords: dicarvone; dimenthol; dipinocarvone; ECD; local modes; NIR-VCD; VCD; vibrational excitons
DOI: 10.1002/chir.23232

Citations: 1
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