The present study is devoted to the combined experimental and theoretical description of the photophysical properties and photodegradation of the new boron-dipyrromethene (BODIPY) derivatives obtained recently for biomedical applications, such as bacteria photoinactivation (Piskorz et al., Dyes and Pigments 2020, 178, 108322). Absorption and emission spectra for a wide group of solvents of different properties for the analyzed BODIPY derivatives were investigated in order to verify their suitability for photopharmacological applications. Additionally, the photostability of the analyzed systems were thoroughly determined. The exposition to the UV light was found first to cause the decrease in the most intensive absorption band and the appearance of the hypsochromically shifted band of similar intensity. On the basis of the chromatographic and computational study, this effect was assigned to the detachment of the iodine atoms from the BODIPY core. After longer exposition to UV light, photodegradation occurred, leading to the disappearance of the intensive absorption bands and the emergence of small intensity signals in the strongly blue-shifted range of the spectrum. Since the most intensive bands in original dyes are ascribed to the molecular core bearing the BF2 moiety, this result can be attributed to the significant cleavage of the BF2 ring. In order to fully characterize the obtained molecules, the comprehensive computational chemistry study was performed. The influence of the intermolecular interactions for their absorption in solution was analyzed. The theoretical data entirely support the experimental outcomes.
Zeta potential is a surface characteristic formed on the solid surface and liquid interface. It is an interesting way to describe the surface properties of materials; thus, a series of four homemade polar embedded stationary phases that contain phosphate groups incorporated into hydrophobic ligands were investigated according to surface zeta potential. Measurements were carried out using Zetasizer Nano ZS for the stationary phases suspensions prepared in various solvent and solvent binary mixtures. The negative zeta potential values were obtained for most cases due to negatively charged residual silanols and phosphate groups. However, in some solvents: tetrahydrofuran, isopropanol, and toluene zeta potential are positive. Additionally, it was observed that the zeta potential seems to be independent of the type of silica gel used for the stationary phase synthesis.