Effect of ionic forms on photoconversion of bisphenol A under the action of solar light
The study investigated the absorption and fluorescence spectra of charged forms of bisphenol A or BPA: anion and cation. The interpretation of the nature of electronically excited states and photolysis of the BPA molecule was made using quantum chemical calculations. Comparison of the BPA spectra in an aqueous solution during the transition from the neutral to ionic form is carried out. Calculations have shown that the small value of the fluorescence quantum yield in all considered molecular structures is determined by the high efficiency of singlet-triplet conversion. In the anionic form of BPA, a decrease by two orders of magnitude in the efficiency of the radiation decay channel was recorded, caused by a change in the orbital nature of the fluorescent state in comparison with the neutral and cationic forms. It is shown that due to the overlap of the absorption spectra of the anionic form in an aqueous solution and sunlight, the probability of photolysis of the studied molecule increases