Time-Resolved Resonance Raman and Density Functional Study of the Radical Cation of Chlorpromazine

Abstract

We have obtained a resonance Raman spectrum of the radical cation of promazine. We have also carried out density functional theory calculations to find the structures, hyperfme coupling constants (hfcc's), spin densities, and vibrational frequencies for the ground electronic states of the neutral chlorpromazine molecule and its radical cation. Preliminary vibrational assignments were made for all of the observed bands in the resonance Raman spectrum of the radical cation of chlorpromazine and in the FT-Raman spectrum of the neutral chlorpromazine molecule. Our results indicate that the radical cation of chlorpromazine has a nonplanar structure similar to that of the radical cation of promazine. However, the chlorine atom at the 2 position in chlorpromazine appears to noticeably change the hfcc's and spin densities of the radical cation compared to the radical cation of promazine. This is possibly due to conjugation and/or through-bond interactions of the chlorine atom with the central-ring heterocycle.