Electrocatalytic Sensing of Para-Hydroxybenzoic Acid Using Metalloporphyrin Microporous Polymers: Effect of the Central Metal

In this study, we synthesized a series of metalloporphyrin-based conjugated microporous polymers (MPor-Tp-CMPs) through a Schiff base condensation reaction between triformyl phloroglucinol (Tp) and metallated tetraaminophenyl porphyrins (CoTAPor, NiTAPor, ZnTAPor). The CMPs were used to modify a glassy carbon electrode (GCE) and applied for electrochemical detection of para—hydroxybenzoic acid (pHBA). It was found that the change in the central metal ions in MPor-Tp-CMPs had a significant effect on the catalytic performance of CMPs, and CoTAPor had the most excellent catalytic property. Under optimized experimental conditions (PBS, pH 7, catalyst loading 70.7 µg.cm− 2), the CoPor-Tp-CMP/GCE sensor exhibited the highest oxidation peak current toward pHBA, which was attributed to the catalytic activity of the cobalt (II) and extended π-conjugated system. A good linearity was obtained in the concentration range of 2 µM to 125 µM, with the sensitivity, limit of detection (LoD), and limit of quantification (LoQ) of 0.180 µA.µM− 1.cm− 2, 1.13 µM, and 3.79 µM, respectively, for CoPor-Tp-CMP/GCE. The sensor showed good reproducibility over multiple electrode fabrications.