The new soluble tetra-substituted oxo-titanium phthalocyanines: Synthesis, characterization, spectral and colorimetric pH sensing properties

New imidazole tetrasubstituted oxo-titanium phthalocyanine 1 was synthesized by tetramerization reac- tion of imidazole substituted phthalonitrile in the presence of titanium(IV) butoxide. N-alkylated imida- zole tetrasubstituted oxo-titanium phthalocyanine 2 was prepared by N-alkylation reaction of compound 1 with iodomethane in basic medium. Afterwards, as a result of the quaternization reaction of compound 2 , water-soluble oxo-titanium phthalocyanine 3 was prepared. The synthesized compounds were charac- terized by UV-Vis, FT-IR, 1 H-NMR, MALDI-TOF MS and elemental analysis. The spectral properties, surface morphologies in powder form and thin films, colorimetric pH sensing properties and aggregation behav- iors of the synthesized compounds were investigated. We also used the UV-Vis spectroscopy technique to experimentally find the optical band gap of compound 1 with the best thin-film surface properties. In this context, transmittance, absorption and band gap energy of compound 1 thin film were investigated.