Mannich reaction derived phthalocyanine polymer for electrochemical detection of salicylic acid

[Display omitted] •The precursor compound is prepared by the Mannich reaction.•The Mannich base was attached to 4-NPN to get polymeric phthalocyanine.•The synthesized Pc was characterized by various physicochemical and analytical techniques.•The polymer with KB was used for the detection of SA using CV, DPV and CA.•The composite hybrid electrode exhibited better sensitivity and reproducibility towards SA. The Mannich base derived polymeric cobalt phthalocyanine poly(CoTAPOPMPPc) was synthesized via three steps viz., i) formation of Mannich base, ii) conversion of Mannich base to oxy bridged phthalonitrile ligand and iii) the cyclotetramerization of oxy bridged phthalonitrile ligand to form polymeric phthalocyanine. The synthesized compounds were in pure state and have been characterized using various physicochemical and analytical techniques. The synthesized polymeric phthalocyanine poly(CoTAPOPMPPc) was immobilized on the glassy carbon electrode and characterised. The carbon nanoparticles (KB) were used for the fabrication of composite electrode GCE/KB-poly(CoTAPOPMPPc) and employed for the detection of salicylic acid (SA) using voltammetry and differential pulse voltametry (DPV). DPV peaks were well-resolved than the peaks observed in the CV. The DPV technique displayed linear response in the range 5–120 μM with limit of detection (LOD) 2 and 1.5 μM and sensitivity 0.0690 and 5.9957 μA μM−1 cm−2 at GCE/poly(CoTAPOPMPPc) and GCE/KB-poly(CoTAPOPMPPc), respectively. The chronoamperometry showed linear range between 0.5 and 4.5 μM salicylic acid with LOD of 0.18 and 0.12 μM with sensitivity of 1.7788 and 8.8245 μA μM−1 cm−2 at GCE/poly(CoTAPOPMPPc) and GCE/KB-poly(CoTAPOPMPPc) electrodes respectively. In addition to better electrocatalytic response for salicylic acid, GCE/KB-poly(CoTAPOPMPPc) did not show response for co-existing molecules inferring a selective response for salicylic acid. The proposed sensor demonstrated better sensing parameters and could be applied in the real sample analysis of SA.