Heteroaggregation between porphyrin and phthalocyanine bearing oppositely charged substituents

Heteroaggregates composed of cationic porphyrin, meso-tetra(p-trimethylamino)porphyrin iodide, its zinc complex and anionic phthalocyanine sodium hydxoxygallium 4,4′,4″,4″′-tetrasulfonated phthalocyanine have been investigated by absorption and fluorescence spectroscopy. It has been found that both free base cationic porphyrin and its zinc complex can form very stable heterodimers with anionic phthalocyanine in water, methanol and dimethylformamide. The stability of the aggregate depends on the polarity as well as the ligation ability of the solvent. No evidence of higher aggregates was detected. Besides axial coordination, steric hindrance which influences the relative orientation of the macrocycles are considered.