Novel metal (II) phthalocyanines with 3,4,5-trimethoxybenzyloxy-substituents: Synthesis, characterization, aggregation behaviour and antioxidant activity

A new substituted phthalonitrile derivative was prepared by a nucleophilic displacement reaction of 3,4,5-trimethoxybenzyl alcohol with 4-nitrophthalonitrile. Novel metallophthalocyanines [M: Zn (II), Co (II), Ni (II)] with four peripheral 3,4,5-trimethoxybenzyloxy groups were synthesized by cyclotetramerization of phthalonitrile derivative. These compounds were purified by crystallization and column chromatography. They were characterized by elemental analysis, FTIR, 1H NMR, 13C NMR and UV–VIS spectral data. The aggregation investigations carried out in different concentrations indicate that 3,4,5-trimethoxybenzyloxy-substituted phthalocyanine compounds do not have any aggregation behaviour in concentration range of 10−2–10−8 M. The antioxidant activities of phthalocyanines were investigated by in vitro antioxidant assays such as free radical scavenging ability of 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferrous ion chelating ability. The highest DPPH activity and ferrous ion chelating activity were obtained from Tetrakis [(3,4,5-trimethoxybenzyloxy) phthalocyaninato] cobalt and 4-(3,4,5-trimethoxybenzyloxy) phthalonitrile, respectively. 4-(3,4,5-trimethoxybenzyloxy) phthalonitrile was shown to have a fairly ferrous ion chelating activity.

► This work reports the synthesis, characterization, aggregation behaviour and antioxidant activity of the new phthalocyanines.
► The spectra showed monomeric behaviour evidenced by a single Q band, typical of metallophthalocyanines compounds in DMF.
► The single Q band depict the monomeric nature of the these complexes in this solvent.
► Compounds 3 and 5 possess chelating activity and DPPH activity.