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The spectral luminescent properties and photolysis of the ionic forms (neutral, cationic and anionic) of bisphenol A have been studied experimentally and by methods of quantum chemistry. Calculations and experiment have shown that, in comparison with a neutral form, no new absorption bands appear in the absorption spectra of ionic form in the range 200–600 nm. The polar solvent (water) shifts the absorption spectrum bands of ionic forms towards low energies. In this case, the shift of the absorption spectrum of the cation is insignificant, and the shift of the anion is significant with an increase in the intensity of the absorption bands. The low quantum yield of fluorescence of ionic form is explained by the prevalence of the efficiency of singlet-triplet conversion over the efficiency of the radiation channel of decay of the fluorescent state. The low quantum yield of fluorescence of the anionic form is due not only to the effective singlet-triplet conversion, but also to the low efficiency of the radiative decay of the fluorescent state of the anion caused by a change in its orbital nature. Calculations have shown that the potential curves of the excited states of bisphenol A and its ionic forms have a significant potential barrier to photolysis. The increase in the efficiency of the process of photodissociation of the bisphenol A anion is caused by a noticeable decrease in the potential barrier and an increase in the overlap of the absorption spectra of the bisphenol A anion and solar radiation.

The electronic excited states of BF 2 dipyrromethene (2BrDPM, DPMI, DPMII, PM567 and 4PhDPM) complexes were investigated using the extended multi-configuration quasi-degenerate at the second order of perturbation theory (XMCQDPT2) and the second-order approximate coupled-cluster (CC2) methods. The excitation energies calculated by CC2 are significantly overestimated by 0.42–0.59 eV because of the substantial contributions of double excitation levels to excited states (>10%). However, the calculated XMCQDPT2 excitation energies agree well with experimental ones within the accuracy 0.11–0.20 eV. The very low lasing efficiency (7.8–8.4%) of 4PhDPM compound was explained by the T 1 → T 4 and T 1 → T 5 reabsorptions at XMCQDPT2 level of theory. The molecular photonics of pyrromethenes are studied using a combination of the first-principle and semi-empirical calculations. The main mechanism for the deactivation of the energy of the first singlet excited electronic state is the radiative electronic transition for DPMI, DPMII, PM567 and 4PhDPM compounds. Also, the main mechanism for the quenching of fluorescence in considered complexes (except DPMII compound) is the internal conversion. The processes of the internal conversion and intersystem crossing compete with each other in DPMII compound. The measured and calculated fluorescence quantum yields agree well for all considered molecules.