Synthesis of 4-(2,6-di-tert-butyl-4-methyl phenoxy) substituted phthalocyanine complexes and investigation of electrochemical and thermal properties

Phthalocyanines are macrocycle compounds with delocalized 18-π electron, consisting of four iminoisoindoline groups. These compounds have potential, applications in several technical areas owing to their electronic structures, stability, physical, and chemical properties. Butylated hydroxy toluene is one of the cresol derivatives substituted with tertiary butyl group which have wider range of applications. In this work, 4-(2,6-di-tert-butyl-4-methylphenoxy)phthalonitrile synthesised from butylated hydroxy tolune (2,6-di-tert-butyl-4-methylphenol) and 4-nitrophthalonitrile. Then phthalocyanine complexes substituted with butylated hydroxy toluene (Li2Pc CoPc, NiPc, CuPc, and ZnPc,) were synthesised. The structures of the synthetic compounds were analysed by various spectroscopic techniques, 1H NMR, 13C NMR, UV-Vis, FT-IR spectroscopy and elemental analysis. The UV-Visible absorption spectra of the metal phthalocyanine complexes showed an intense Q band which started from 669 nm for CoPc, 675 nm Li2Pc, 677 nm NiPc, 679 nm ZnPc, and last one 723 nm of CuPc. Thermal analysis was performed by thermogravimetric (TGA) and differential thermal analysis (DTA) method showed phthalocyanine complexes stable in wide range of temperature (weight lost start from 200, 230, 230, 250, and 250 °C) for (Li2Pc, ZnPc, CuPc, CoPc, and NiPc) respectively. Electrochemical properties were investigated in DMSO by cyclic voltammetry (CV) and square wave voltammetry (SWV). All the metal phthalocyanine complexes showed redox waves both in oxidation and reduction potentials belong to phthalocyanine ring. CoPc complexes have extra redox potential belong to central metal atom cobalt.