Mestranol moieties clicked to Zn(II)phthalocyanine for controllable photosensitized oxidation of cholesterol

Abstract

Four mestranol moieties were chemically linked to Zn(II) phthalocyanine (4) by cycloaddition “Click” reaction using a tetra-azidoethoxy substituted Zn(II)-phthalocyanine (3). The alkyl-azido coupling reaction was realized between azido groups of 3 and alkyl group of mestranol. The alkylation reaction was carried out to obtain cationic Zn(II) phthalocyanine derivative (5). The new compounds were chemically characterized by the known analytical methods. The absorption and fluorescence properties were studied in comparison. The absorption maxima of phthalocyanines 3, 4 and 5 were recorded at approx. shifts of 8 - 12 nm in the far- red region (680 - 684 nm) and the fluorescence maxima (692 - 693 nm) as compared to unsubstituted ZnPc (672 nm, 680 nm) in DMSO. The studies of singlet oxygen generation of 3, 4 and 5 showed relatively high values such as 0.52 for 3; 0.51 for 4 and 0.46 for 5. The fluorescence lifetime of 3.15 ns (3), 3.25 ns (4) and 3.46 ns (5) were determined with lower than the value than for the used standard ZnPc (3.99 ns). The high photo stability was observed for compounds 3, 4 and 5. In addition, the photosensitized oxidation of cholesterol was compared for 3 and 4 with much lower values of oxidation potential than for unsubstituted ZnPc which suggests that the substitution groups influenced on the photooxidation index of the target molecule.