Spectral-Luminescent Properties and Photolysis of Charged Forms of Bisphenol A

摘要

Spectral-luminescent properties and photolysis of charged forms (cation and anion) of bisphenol A are studied experimentally and by methods of quantum chemistry. The calculations and the experiment demonstrate that no new absorption bands appear in the absorption spectra of charged forms in the region of 200-600 nm as compared to a neutral molecule. The polar solvent (water) shifts the absorption spectrum bands of the ionic forms to the region of low energies. In this case, the shift of cation absorption spectrum is insignificant, while the shift of anion absorption spectrum is significant as the intensity of absorption bands increases. The low quantum yield of fluorescence of ionic forms is explained by the predominance of singlet-triplet conversion efficiency over the efficiency of the radiation channel of fluorescent state decay. The low quantum yield of fluorescence of the anion form is due not only to the effective singlet-triplet conversion, but also to the low efficiency of the radiation decay of the fluorescent state of the anion caused by a change in its orbital nature. Calculations demonstrate that the potential curves of the excited states of bisphenol A and its ionic forms have a significant potential barrier for photolysis. An increase in the potential reaction barrier in the cation decreases the efficiency of its photolysis. The increase in the photodissociation efficiency of the bisphenol A anion is caused by a noticeable decrease in the potential barrier and an increase in the overlap between the absorption spectra of the bisphenol A anion and the solar radiation.