Syntheses and photochemical properties of octasubstituted phthalocyaninato zinc complexes

In this work a selection of octasubstituted phthalocyaninato zinc complexes were synthesized and their photochemistry studied. The substituents included cholesterol (3a), estrone (3b), naphthol (3c) and phenoxy groups substituted with CH 3 (3d), C ( CH 3 ) 3 (at two positions, 3e), C ( CH 3 ) 3 (3f), NO 2 (3g), NH 2 (3h), COH (3i), COOH (3j), and H (3k). In general, complexes containing electron-donating groups attached to the phenoxy ring (e.g. 3e and 3f) were found to be photochemically unstable with photobleaching quantum yields of the order of 10 -3 . In the presence of electron-withdrawing groups (3g, 3i, and 3j) the photobleaching quantum yields were of the order of 10 -6 to 10 -5 . Singlet oxygen quantum yields (Φ Δ ) ranged from 0.01 to 0.73. The lowest Φ Δ was observed for the highly aggregated complex 3c. All the complexes showed aggregation at high concentrations. Electrochemical reduction using a thin-layer spectroelectrochemistry cell showed that the complexes become more monomeric following reduction.