Influence of progressive halogenation of Zn(II)-tetraarylporphyrins and their free bases on the structure and spectral-fluorescence properties of tetrapyrrolic macrocycle

Abstract

Zn(II)-2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetra-(2,6-difluorophenyl)porphyrin was synthesized by the interaction of Zn(II)-5,10,15,20-tetra-(2,6-difluorophenyl)porphyrin with N-bromosuccinimide in a mixture of chloroform-methanol, chloroform-dimethylformamide and in dimethylformamide. Zn(II)-2,3,7,8,12,13,17,18-octachloro-5,10,15,20-tetra-(2,6-difluorophenyl)porphyrin was formed by the reaction of 2,6-difluoro-substituted Zn(II)-porphyrin with N-chlorosuccinimide in the chloroform-methanol mixture and dimethylformamide. Zn(II)-2,3,7,8,12,13,17,18-octachloro-5,10,15,20-tetra-(2,3,4,5,6-pentafluorophenyl) porphyrin was synthesized from Zn(II)-5,10,15,20-tetra-(2,3,4,5,6-pentafluorophenyl)porphyrin with an excess of N-chlorosuccinimide via chlorination in dimethylformamide. The corresponding porphyrin-ligands were obtained by treating halogen-substituted zinc porphyrins with trifluoroacetic acid. The synthesized compounds were characterized by UV–Vis, fluorescence, 1H NMR spectroscopy and mass spectrometry methods. The structures of halogen-substituted porphyrins and their Zn(II) complexes were calculated by the DFT method. The effect of the β-pyrrole halogenation on fluorescence quantum yields of the synthesized compounds was estimated. These halogenated products can be employed for covalent functionalization of the macrocycle pyrrole fragments with the aim of imparting practically important optical, electrochemical and red-ox properties to them.