Vibronically-induced change in the chiral response of molecules revealed by electronic circular dichroism spectroscopy

A computational study of the vibronically resolved electronic circular dichroism (ECD) spectra of R-(+)- 3-methyl-cyclopentanone, including both Franck-Condon and Herzberg-Teller contributions, shows how the latter can introduce a change of sign on the chiral response of an electronic excited state. This sign inversion within the vibronically resolved electronic band, which can be interpreted as a change of the chirality of the system, has in principle important consequences in comparisons of theoretical and experimental ECD spectra employed for the assignment of absolute configurations. (C) 2008 Elsevier B.V. All rights reserved.