Synthesis and electropolymerization of cobalt tetraaminebenzamidephthalocyanine macrocycle for the amperometric sensing of dopamine

Cobalt (II) tetra[β-N-(4-nitrophenyl) benzamide] phthalocyanine (CoTNBAPc) complex was synthesised in pure state for the first time and was reduced to respective aminephthalocyanine (CoTABAPc). The synthesised complexes were characterised by elemental analysis, UV–Visible, FTIR and TGA techniques. The benzamidephthalocyanine derivatives exhibited redox peaks corresponding to the central metal (Co+2/Co+1) and macrocycle (Pc−2/Pc−3) and in addition, a small shoulder peak was observed for the amine oxidation. The peripheral primary amine of the phthalocyanine undergoes oxidative polymerization and forms polymeric film on the electrode surface in DMSO solvent. The polymeric film modified electrode was used for the voltammetric and amperometric detection of dopamine (DA) and voltammetric method showed linear response in the concentration range 100–4000nmolL−1. Whereas, the amperometric method showed linear response in the concentration range of 100–1000nM and the correlation coefficient (R2) was found to be 0.999 with limit of detection (LOD) 20nmolL−1 and the sensitivity was 0.024μAnmol−1cm−2 for DA. The fabricated sensor was also used for the amperometric sensing of dopamine in real sample. Other co-existing molecules did not show overlapping peaks for the oxidation or interference during the determination of dopamine. [Display omitted] •New cobalt (II) tetra[β-N-(4-nitrophenyl) benzamide] phthalocyanine complex has been synthesised in pure state.•The synthesised ligand and complex were characterised by spectroscopic as well as electrochemical techniques.•The complex is electrochemically active and undergoes electropolymerization on electrochemical cycling.•The polymeric film modified electrode was employed for the nano molar detection of dopamine.•The modified electrode is selective and sensitive for amperometric sensing of dopamine.