Synthesis and photophysicochemical properties of a set of asymmetrical peptide conjugated zinc(II) phthalocyanines bearing different fluorophore units

Abstract

A set of asymmetrical Zn(II) phthalocyanine complexes bearing the branched polyoxoethylene chains to increase water-solubility, the peptide sequence and the fluorophore group as quenchers of fluorescence were synthesized and characterized for the first time. A Matrix Metalloproteinases (MMP) substrate peptide sequence was used as a linker between the phthalocyanine core and fluorophore moiety. Each of the complexes were linked with different fluorophore groups to compare effects of the flourophores on the photoactivity of the phthalocyanines. As expected, the binding of the fluorophore groups to the phthalocyanine core decreased both fluorescence and singlet oxygen quantum yields of newly synthesized photosensitizers about 80% which were served as a quencher. It is suggested that an energy transfer was occurred between the Zn(II) phthalocyanine core and fluorophore groups, so photosensitizers' singlet oxygen generation abilities can be controlled until these photosensitizers interact with MMP enzyme in the tumor cells. (C) 2016 Elsevier B.V. All rights reserved.