Synthesis and characterization of near-IR absorbing metal-free and zinc(II) phthalocyanines modified with aromatic azo groups

Abstract

Metal-free and zinc(II) phthalocyanine complexes bearing peripheral (E)-4-((2-hydroxynaphthalen-1-yl)diazenyl) units have been synthesized. Novel phthalonitrile derivative required for the preparation of phthalocyanine complexes was prepared by coupling 4-aminophthalonitrile and 2-naphthol. The structures of these new compounds were characterized by using elemental analyses, proton nuclear magnetic resonance, fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, fluorescence spectroscopy and mass spectrometry. In the UV-Vis spectra a broad absorption band appears for phthalocyanine complexes at around 450–500 nm resulting from azo-group introduced onto the phthalocyanine ring. The photophysical properties of metal-free and zinc(II) phthalocyanines were studied in tetrahydrofuran.