Cationic Zn and Al phthalocyanines: synthesis, spectroscopy and photosensitizing properties

Abstract

Several Zn (II) and Al (III) phthalocyanines bearing eight or sixteen positive charges on substituents of different structure have been prepared. Synthesized polycationic phthalocyanines have been studied in aqueous and alcoholic media by UV-vis spectroscopy and tested for their efficacy in singlet oxygen photosensitization. It has been found that a minor structural modification at the periphery of the photosensitizer allows control over its key features such as singlet oxygen generation due to specific intermolecular interactions in solution. The efficacy of polycationic phthalocyanines to sensitize tryptophan photobleaching in aqueous media and inactivation of bacteria in sewage water is also structure-dependent. Among the complexes studied, two dyes - zinc octakis(pyridiniomethyl)- and octakis[ N -(2-hydroxyethyl)- N , N -dimethylammoniomethyl]substituted phthalocyanines - are the best sensitizers and have high potential for photodynamic applications.

Improvement of Heterogeneous Sensitizer Photobactericidal Activity by Elongation of Linker between Phthalocyanine and Silica Gel Support

“…Fluorescence quantum yield for SiPcChol 8 in water was determined as described in. [14] Singlet Oxygen Detection Quantum yield of singlet oxygen production by SiPcChol 8 in aqueous solution was determined as described in [15] with the BPAA water-soluble cationic singlet oxygen trap.…”

The synthesis and photophysical properties of novel cationic tetra pyridiloxy substituted aluminium, silicon and titanium phthalocyanines in water

“…For example, for a series of zinc and aluminium phthalocyanines substituted with pyridiniomethyl groups, as the number of cation substituents increased, the aggregation ability of phthalocyanines were found to decrease in aqueous media, and the quantum yields of fluorescence and singlet oxygen generation increased as well as the photodynamic inactivation of bacteria [25,26]. The reason for such monomeric state of these complexes was attributed to strong electrostatic repulsive force of eight charges thereby preventing the formation of the aggregates [25].…”

“…The reason for such monomeric state of these complexes was attributed to strong electrostatic repulsive force of eight charges thereby preventing the formation of the aggregates [25]. However, it has been documented that tetrasubstituted phthalocyanines are more soluble than their octa-substituted counterparts due to formation of constitutional isomers and that they possess high dipole moments [21], hence they are studied in this work.…”

“…Cationic AlPc complexes containing pyridiloxy substituents have been reported [25], but no photophysical data is available on these complexes. Also quaternized TiPc complexes containing pyridiloxy groups are reported in this work.…”

Photosensitized oxidation by dioxygen as the base for drinking water disinfection

“…Effect of sensitizer concentration on total coliform bacteria survival (in CFU per 10 −1 dm 3 ) for photodynamic treatment with ZnPcPym 8 (1) and methylene blue(2). Contact time of incubation: 1 h, irradiation time: 0.5 h.…”