Stable Zr(iv) coordination polymers with electroactive metal-terpyridine units for enhanced electrochemical sensing dopamine

Abstract

Coordination polymers (CPs) have attracted remarkable attention in electrochemical sensing for their high selectivity and sensitivity. However, CPs with desired electroactivity and stability for electrochemical sensing in aqueous solution still remain to be developed. Herein, two stable Zr(IV)-based CPs, [M₂Zr₂(HCOO)₈(cptpy)₄]_n·solvent [M = Fe, named Fe-CP; M = Ni, named Ni-CP; HCOO⁻ = formate; Hcptpy = 4′-(4-carboxylphenyl)-2,2′:6′,2′′-terpyridine], with incorporated electroactive metal-terpyridine moieties were explored, using electrochemical dopamine (DA) sensing as a model. Compared with electroactive ligands, Fe-CP and Ni-CP have a large diffusion coefficient and fast electron transfer rate towards DA oxidation, resulting in enhanced signals. The CPs show a low detection limit of 40 nM for Fe-CP and 62 nM for Ni-CP as well as a wide detection range with high selectivity, satisfactory reproducibility and stability. Additionally, the capacity of DA detection on these CP modified electrodes in simulated urine further demonstrates their feasible application in real systems.