Synthesis, electrochemical and photophysical studies of axially substituted quarternizable titanyl phthalocyanines

This work reports on the synthesis, characterization, photophysical properties and electrochemical characterization of new tetra-substituted titanium phthalocyanine with dimethylaminoethanol groups on peripheral positions (2) and water-soluble quaternized counterpart. The water-soluble titanium(IV) phthalocyanine derivative (3) was found to be aggregated in aqueous media but was partially or fully disaggregated in the presence of a surfactant Triton X-100. The capping of the titanyl (metaloxo) inner core with catechol derivatives (4-7) were also synthesized. The axially substituted titanium phthalocyanines show high solubility and a low aggregation tendency due to the steric hindrance. The structures of these compounds were characterized by using elemental analyses, UV-Vis, FT-IR, ¹H NMR and mass spectroscopies. Their photophysical properties were also studied and fluorescence quantum yields were found to range from 0.02 to 0.13. The electrochemical properties of 2 were also investigated by using cyclic voltammetry in this report.