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.