Synthesis, photophysical and photochemical properties of amphiphilic carboxyl phthalocyanine oligomers

The synthesis and photochemical properties are reported for a series of novel amphiphilic carboxyl polymeric phthalocyanines, with zinc (3a), aluminum (3b), ytterbium (3c) and hydrogen (metal-free, 3d) as the substituted central atom, respectively. The synthesis routes included cyclotetramerization of tetra-phthalonitriles and subsequent hydrolysis of cyano to carboxyl in alkaline solution. All four molecules were verified to be oligomers by viscosity method. Specifically, 3c showed strongest fluorescent emission, which can be elevated by Triton X 100 and CTAB. The singlet oxygen quantum yield (Φ _Δ) for 3a and 3b were larger than that of 3c and 3d. In the presence of surfactants, nearly 2 folds enhancement of Φ_Δ was observed as 0.76 and 0.70 for 3a and 3b, respectively. The characteristic photochemical properties of these oligomers suggested potential applications in photodynamic therapy, photocatalysis and photodynamic diagnoses.