A novel phthalocyanine conjugated with four salicylideneimino complexes: Photophysics and fluorescence quenching studies

A novel phthalocyanine with four salicylideneimino ligating groups directly conjugated to the macrocyclic core has been synthesized by the condensation of tetramino-phthalocyanine with salicylaldehyde. Complexation on the periphery to obtain pentanuclear complex has been accomplished either directly through the reaction of this phthalocyanine, 8-hydroxyquinoline as the second ON donor ligand and zinc (II) salt or zinc (II) complex of 8-hydroxyquinoline has been isolated first and then it has been reacted with the phthalocyanine carrying salicylideneimino ligating groups. Also a new mixed ligand Schiff base complex of Zn (II) as a model containing salicylaldimine ligand and 8-hydroxyquinoline has been synthesized to compare with the complex. The new compounds have been characterized by elemental analysis FTIR, 1H NMR, UV–Vis spectroscopy and mass spectrometry. General trends are described for fluorescence lifetimes and fluorescence of these compounds in dimethylsulfoxide, dimethylformamide and tetrahydrofurane. The solvent effect on the photophysical parameters of the zinc (II) phthalocyanines and the model zinc (II) complex is also studied. The fluorescence of the substituted zinc (II) phthalocyanine complexes is effectively quenched by 1,4-benzoquinone (BQ) in these solvents.

A novel zinc phthalocyanine with four salicylideneimino moieties directly conjugated to the macrocyclic core and its pentanuclear complex have been synthesized. The fluorescence of these substituted zinc (II) phthalocyanine complexes is effectively quenched by 1,4-benzoquinone.Figure optionsDownload as PowerPoint slideHighlights
► New phthalocyanine-salicylaldimine dyads were prepared and characterized.
► Pentanuclear complex formation on a totally conjugated pi-system was accomplished.
► Fluorescence lifetimes and fluorescence of these compounds are studied.
► Fluorescence quenching tests on mono and pentanuclear complexes were carried out.