Fluorescent and Acid-Base Indicator Properties of Complexes Based on Sn(IV) Octaethylporphyrinate and Molecules of Dye: Phenolphthalein and 1,3,5,7-Tetramethyl-8-(4-hydroxyphenyl) (BODIPY)

Abstract— Triads L–SNP–L, containing two ligands, phenolphthalein or 1,3,5,7-tetramethyl-8-(4-hydroxyphenyl)-4,4-difluoro-4-boron-3a,4a-diazaindacene (BODIPY), axially bound to Sn(IV)octaethylporphyrinate, were synthesized. The sensitivity of the obtained triads to changes in the acidity of the medium has been studied. Photoexcitation of the BODIPY-SnP-BODIPY triad leads to photoinduced energy transfer from the BODIPY donor fragments to the porphyrinate acceptor. When the triad is excited at the wavelength λ_exc = 490 nm, in addition to BODIPY fluorescence, fluorescence sensitized by the porphyrin fragment is recorded, and when the triad is excited at a wavelength λ_exc = 400 nm, porphyrinate fluorescence flares up compared to initial SnP. In the triad with phenolphthalein molecules, the fluorescent properties of both the ligand and porphyrinate are quenched, however, sensitivity to changes in the solution pH increases.