Electrochemical Behavior and Analytical Applications of Self‐Assembled Monolayers on Gold Electrode with a Cobaltous Porphyrin

Abstract

A porphyrin 5‐(4‐hydroxyethoxyphenyl)‐10,15,20‐tris‐phenylporphyrin (HEPP) was synthesized. The voltammetric behavior of gold electrodes modified with neutral free‐base and positively charged cobaltous center porphyrin films through exposed hydroxyl and pre‐assembled carboxyl terminal via coupled reaction were investigated using Fe(CN)₆ ^3−/4−, ascorbic acid (AA), and dopamine (DA) as probe species. The voltammetric sensing of AA at the physiological level in the presence of DA can be achieved on functionalized self‐assembled monolayer (SAM) of short chain cobaltous porphyrin. The selectivity of response can be improved by introducing structural defects and positively charged center (Co²⁺) in monolayer modified electrode. The results showed that the current of AA anodic peak and its concentration had a linear relationship in a wide range of concentration from 4 × 10⁻⁷ to 2 × 10⁻² mol L⁻¹. The detection limit obtained by differential pulse voltammetry was 6.9 × 10⁻⁸ mol L⁻¹.

Keywords:

• Cobaltous porphyrin
• Self‐assembled monolayers
• Ascorbic acid
• Dopamine
• Electroanalysis

Acknowledgments

The present work was supported by a grant from the National Natural Science foundation of China (Nos. 20275031 and 20335030) and KJCXGC‐01 from Northwest Normal University. The authors were also grateful to the State Key Laboratory of Electroanalytical Chemistry (SKLEAC) Foundation, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences.