Synthesis of novel azo group substituted polymeric phthalocyanine for amperometric sensing of nitrite

[Display omitted] •Synthesised novel polymeric azosubstituted phthalocyanine and characterized.•Modification of the surface was done with the polymer and carbon nanoparticle.•The modified electrode showed good amperometric response for nitrite oxidation.•The method is simple, sensitive and stable. The novel tetraazo-bridged cobalt phthalocyanine polymer [poly(TazoCoPc)] was synthesized by oxy-bridge to extend the conjugation effect on the phthalocyanine molecule. Firstly, the ligand [phenyl-1,4-bisdiazenyl naphthalene-1-oxy] benzene 1,2-dicarbonitrile was prepared and it was characterized. Then, the polymeric phthalocyanine was prepared and characterized by elemental analysis, UV–vis, FTIR, TGA, XRD and electrochemistry. Polymeric phthalocyanine and carbon nanoparticles (CNP) were mixed and used for modifying the glassy carbon electrode to fabricate the electrochemical voltametric and amperometric nitrite sensor. Composite of phthalocyanine polymer and CNP exhibits enhanced electrocatalytic behaviour for the oxidation of nitrite compared to pure polymeric phthalocyanine. The fabricated amperometric sensor exhibits excellent analytical performance for nitrite detection in the concentration range of 20 nM to 1 μM with a detection limit of 6 nM (S/N = 3) and a sensitivity of 0.137 mA/μM. The modified composite electrode is highly selective and it didn’t show any interference effect even in presence of excess interfering ions such as Mg2+, SO42−, K+, CO32−, NO3-.