EFFECTS OF LIGANDS, SOLVENT, AND VARIABLE SULFONATION ON DIMER FORMATION OF ALUMINUM AND ZINC PHTHALOCYANINESULFONATES

The absorption spectra and emission spectra in aqueous solution of three types of phthalocyaninesulfonates of aluminum are compared: IA, a trisulfonate formed by sulfonation of aluminum phthalocyanine, shows no evidence for dimerization in water with changing pH or ionic strength. IIA, a tetrasulfonate prepared by metalation of the tetrasulfonated free base using Al(acac)3, when added to water immediately shows spectra characteristic of a "contact dimer". IIIA, a tetrasulfonate prepared by condensation of sulfophthalic acid around AlCl3, also shows dimer-like spectral changes, but they develop over 4 h. This "slow-forming dimer", like the "contact dimer", shows no emission but has a sharper red band. Comparison is made to similarly prepared phthalocyaninesulfonates of zinc: IZ, IIZ, IIIZ. Again, there is little dimer formation by IZ, although somewhat more than by IA. The zinc phthalocyaninetetrasulfonates, IIZ and IIIZ, show large amounts "contact dimer" but no "slow-forming dimer" spectrum, which is attributed to formation of a binuclear mu-oxo aluminum phthalocyaninetetrasulfonate.