Formation, characterization and electrochemical properties of novel tetrasubstituted cobalt phthalocyanines bearing tetrahydropyran, furan and coumarin moieties

Cobalt phthalocyanines (CoPcs) bearing peripherally tetrasubstituted tetrahydropyran (thp) or furan (fur) moieties were formed and spectroscopically characterized. Structural elucidations of 4-(tetrahydropyran-2-methoxy)phthalonitrile (1) and 4-(furan-2-methylthio) phthalonitrile (2) were confirmed via single crystal X-ray analysis. The redox properties of CoPc-thp (3) and CoPc-fur (4) were investigated via cyclic and squarewave voltammetry as well as UV-Vis spectroelectrochemistry. Glassy carbon electrodes (GCEs) modified with 3, 4 and a previously reported coumarin (cou) substituted CoPc (CoPc-cou, 5), were tested for their electrocatalytic activities toward L-cysteine. While the bare GCE and 4-GCE showed no peaks for L-cysteine oxidation in the 0.0-0.70 V potential window; 3-GCE and 5-GCE showed peaks at 0.42 V and 0.52 V, respectively. Kinetic parameters were determined by chronoamperometry studies. L-Cysteine oxidation using 3-GCE was found to proceed at a faster rate than 5-GCE. (C) 2016 Elsevier B.V. All rights reserved.