Enhanced Electrocatalytic Activity of Thiophene-Substituted Asymmetric Porphyrin Film for Electrochemical Determination of Dopamine

Thiophene substituted porphyrin derivative was synthesized and investigated. The porphyrin derivative was characterized via MALDI-MS, H-1 NMR, FT-IR, and cyclic voltammetry methods. The poly-porpyrin (PPor) film was electrochemically deposited on a glassy carbon electrode (GCE) via cyclic voltammetry in phosphate buffer solution (PBS). The electrocatalytic activity of the polymeric porphyrin film-modified electrode (GCE-PPor) was investigated towards dopamine through differential pulse voltammetry (DPV) method. The electrochemical results revealed that GCE-PPor exhibited a better catalytic activity towards dopamine in PBS when compared to an unpolymerized porphyrin-modified electrode. The PPor-modified electrode shows a sensitivity of 5.82 mu A mu M-1 cm(-2) and low detection limit of 0.42 mu M with high selectivity in the presence of ascorbic acid (AA) and uric acid (UA) as interferents. The enhancement of the electrocatalytic activity can be explained by the enhanced pi-conjugation after polymerization.