Sulfur bridged new metal-free and metallo phthalocyanines carrying 1,2,4-triazole rings and their photophysicochemical properties

Abstract The novel metal-free (4) zinc(II) (5) and lead(II) (6) phthalocyanines containing 1,2,4-triazole groups connected to the phthalocyanine ring by S-bridge were synthesized and characterized. For this purpose, the original 2-(4-chlorobenzoyl)-N-(4-fluorophenyl)hydrazinecarbothioamide (1) was synthesized as a result of the reaction of 4-chlorobenzyl hydrazide and 4-fluorophenyl isothiocyanate. It was obtained 5-(4-chlorophenyl)-4-(4-fluorophenyl)-4H-1,2,4-triazole-3-thiol (2), which is a new compound by the ring closure reaction of 1. The other original compound 4-[5-(4-chlorophenyl)-4-(4-fluorophenyl)-4H-[1,2,4]triazol-3-yl sulfanyl]-phthalonitrile (3) was synthesized by the nucleophilic aromatic substitution reaction of 4-nitrophthalonitrile and compound 2. Starting from the new phthalonitrile (3), the metal-free (4), zinc(II) (5) and lead(II) (6) phthalocyanines (Pcs) were prepared. Six new compounds were synthesized, and their structures were characterized by elemental analysis and 1H NMR, 13C NMR, FT-IR, MALDI-TOF MS and UV–vis spectral data in this work. The photophysical and photochemical properties of the synthesized phthalocyanines were investigated for determination of their usability as photosensitizers (PS) for photodynamic therapy (PDT) applications. © 2021 Elsevier Ltd. All rights reserved.