The spectral-shapes of Absorption, Emission, ECD and CPL of a Fluorene-fused [7]helicene: vibronic effect and solvent inhomogenous broadening

Abstract We compute the line shapes of absorption (ABS), emission (EMI), electronic circular dichroism (ECD), and circularly polarized luminescence (CPL) of a fluorene-fused [7]helicene. To elucidate different physico-chemical factors responsible for the spectral shapes, we account for Franck-Condon (FC) contribution, Herzberg-Teller (HT) effect and Duschinsky rotation, as well as the solvent inhomogenous broadening. The latter is connected to the solvent reorganization energy which is calculated with the state-specific (SS) implementation of Polarizable Continuum Model (PCM). To understand the relative importance of different effects of equilibrium geometry displacements, frequencies changes, and Duschinsky mixing, we carefully compare and discuss the results of Adiabatic Hessian (AH), Adiabatic Shift and Frequencies (ASF), and Adiabatic Shift (AS) models in details. Our results agree with the experimental spectra very well. They show that FC contribution dominates the spectra and HT effect leads to the break of mirror images between absorptive (ABS+ECD) and emissive (EMI+CPL) spectra.