Phthalocyanines bound to insoluble polystyrene. Synthesis and properties as energy-transfer photosensitizers

Metallotetracarboxyphthalocyanines (MTCPc, M = Cu, Al) were bound to the amino groups of Amberlite IRA-93 by arnide bonding. The insoluble materials obtained were characterized by IR absorption, visible absorption and diffuse reflectance, and ICP atomic emission spectroscopy, and tested for energy transfer under irradiation in the phthalocyanine Q-band. Samples containing AlTCPc are strongly fluorescent both in the solid state and in DMF suspension. Fluorescence quantum yields decrease sharply in toluene suspension. In the solid state, fluorescence may be quantitatively quenched by energy-transfer to an adsorbed dye. Singlet molecular oxygen (1O2) quantum yields were obtained in suspension by monitoring the photooxidation of diphenylisobenzofuran. Values are drastically reduced in DMF suspension and even more in toluene suspension relative to homogeneous solution. This fact is attributed to dye aggregation (M = Cu) and excited-state self-quenching (M = Al). Results can be rationalized by assuming that MTCPc incorporation occurs mainly at the polymer surface and that dye-to-dye interaction in suspension depends strongly on the environment. © 1997 Elsevier Science S.A.