Effect of the structure of the meso-alkyl substituent on the physicochemical and coordination properties of the porphyrin ligand

Abstract

The acid-base and coordination properties for the series of meso-alkyl substituted porphyrins were studied spectrophotometrically: 5,10,15,20-tetrabutylporphyrin (H2(n-Bu)4P), 5,10,15,20-tetra-iso-butylporphyrin (H2(i- Bu)4P), 5,10,15,20-tetrakis(tert-butyl)porphyrin (H2(t-BuP)4), 5,10,15,20-tetra(trifluoromethyl)porphine (H2(CF3)4P). The electronic absorption spectra of molecular and ionized forms of meso-substituted porphyrins in acetonitrile, acid constants and basic ionization of the porphyrins were measured. It is shown that a change in the structure of the mesosubstituent in the porphyrin macrocycle drastically changes the acid-base and coordination properties of the porphyrin. The analysis of complex formation of the molecular and dianionic forms of the porphyrin with zinc acetate has been made.