LAUSR

Abstract Analogs of amide bridge cobalt phthalocyanine complexes with different peripheral substituents have been prepared with good yield and these dyes possess dark green colour. These phthalocyanine complexes are characterized by elemental analysis, absorption spectra, infrared spectroscopy, mass and electrochemical methods. An attempt has been made to understand the structure–property relationship of these molecules for electrochemical properties. Hence, uniform and thin film of amide phthalocyanine (Pc) complex was administered on glassy carbon electrode (GCE) surface and scanning electron microscopy (SEM) images displayed the uniform distribution of the macrocycle on the surface. The modified electrodes are found to be electroactive and the Ohmic/Faradic surface response of the film is studied using electrochemical impedance spectroscopy (EIS). The formal Co(II)/(I) redox behavior of the substituted phthalocyanines have been explained using Hammett parameter. The electrode surface modified with terminal amide bridged Co-N4 macrocyclic complexes were applied for the sensing of hydroquinone (QH2). An attempt was made to understand the influence of structure and functional groups on the electrocatalytic activity. Cyclic voltammetry (CV) displayed significantly increasing current trend for QH2 in the quantitative range 200–2200 nM at the furan containing amide phthalocyanine (CoTAMFCAPc) electrode with a low limit of detection (LOD) of 65 nM. Further, the chronoamperometric analysis showed better linear response for QH2 in 170–1530 nM range with LOD 56 nM at GCE/CoTAMFCAPc electrode compared to other molecules. The fabricated GCE/CoTAMFCAPc electrode demonstrated good stability and selectivity for QH2 in presence of molecules with similar structure which co-exist along with QH2. GCE/CoTAMFCAPc electrode can be employed for practical application and produced superior recovery values for QH2.