Theoretical study of the electronic spectra of azobenzene dyes

Molecular structures of 43 azobenzene derivatives were calculated by DFT-B3LYP//cc-pVDZ method. The absorption spectrum and the electron transition of each studied molecule were obtained through the analyses of 10 excited states by the ZINDO/S//B3LYP/cc-pVDZ, CIS//B3LYP/cc-pVDZ, and TD//B3LYP/cc-pVDZ methods. For the symmetric molecules, the electron transitions are π-π* transition. Not all the transitions are the HOMO, LUMO transition. In order to compare the theoretical results of the absorption maxima with the experimental ones, multivariable linear regression methods were selected, considering numerous variables. Correlation equations were given at the 95% predictive interval.