Syntheses and photochemical properties of octasubstituted phthalocyaninatozinc complexes

In this work a selection of octasubstituted phthalocyaninato zinc complexes were synthesized and their photochemistry studied. The substituents includ ed cholesterol (3a), estrone (3b), naphthol (3c) and phenoxy groups substit uted with CH3 (3d), C(CH3)(3) (at two positions, 3e), C(CH3)(3) (3f), NO2 ( 3g), NH2 (3h), COH (3i). COOH (3j), and H (3k). In general, complexes conta ining electron-donating groups attached to the phenoxy ring (e.g. 3e and 3f ) were found to be photochemically unstable with photobleaching quantum yie lds 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 (Phi (Delta)) ranged from 0.01 to 0.73. The lowest Phi (Delta) was observed for the highly aggregated com plex 3c. All the complexes showed aggregation at high concentrations. Elect rochemical reduction using a thin-layer spectroelectrochemistry cell showed that the complexes become more monomeric following reduction. Copyright (C ) 2001 John Wiley & Sons, Ltd.