Fe(II)-Based Metallo-Supramolecular Polymer Film for Electrochemical Detection of Nitrite: Studies of Kinetics and Reaction Mechanisms

Abstract

Here, a monometallic supramolecular polymer (SMP) was synthesized for the fabrication of an electrochemical nitrite sensor, and a mechanism for nitrite detection was proposed based on the experimental findings. The SMP (polyFe) was synthesized using a symmetrical ligand containing terpyridine moieties [4′,4′′′′-(1,4- Phenylene) bis(2,2′:6′,2′′-terpyridine)] and ferrous acetate. Various analytical methods, such as ultraviolet/visible (UV/Vis) titration, field-emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), and energy dispersive X-ray spectroscopy (EDS), were used to characterize polyFe. The molecular weight of polyFe was calculated from the intrinsic viscosity measurement using the Mark-Houwink-Sakurada equation. The electrochemical behavior of the fabricated sensor was investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The variation in scan rate from CV was used to investigate the kinetics of nitrite oxidation. A possible reaction mechanism was proposed based on the kinetic studies. The proposed sensor showed a good linear range of 2.49 μM to 1.23 mM and a limit of detection of 0.17 μM. Stability, interference, and reproducibility of the proposed sensor were also investigated. The CV technique was used to demonstrate the applicability of the nitrite sensor for real sample analysis. A satisfactory recovery with a low relative standard deviation was achieved.