Aggregation behavior and UV-vis spectra of tetra- and octaglycosylated zinc phthalocyanines

Several tetra-and octaglycosylated PcZn's 1a, 2a-2d, 3a-b and 4 were investigated for their aggregation behavior using different concentrations of the PcZn-species in pure DMSO, water and in various DMSO/water mixtures by comparing their UV-vis spectra. The PcZn's 1-4 are independent of the concentration in pure DMSO and in up to 25 vol.% water/DMSO mixtures are non aggregated. Increasing amounts of water leads to higher aggregation ratios. The aggregation behavior is influenced by the nature and the position of the sugar substituents on the Pc-ring. PcZn 4 was found the least aggregated compound even in pure water.