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 titration, field-emission scanning electron microscopy, Fourier transform infrared spectroscopy, and energy dispersive X-ray spectroscopy, 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. 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.

In this work, we report the synthesis of a mono metallic supramolecular polymer for constructing a new nonenzymatic electrochemical nitrite sensor. Metallo supramolecular polymer have been prepared by the complexation reaction of a ligand bearing terpyridine moieties [4′,4′′′′-(1,4 Phenylene) bis (2,2′:6′,2′′-terpyridine] with Fe(II) salts (Fe salt: Ligand-1:1) (polyFe). The polyFe was characterized with the UV/Vis titration and FTIR. The glassy carbon electrode (GCE) was used for fabricating ployFe_GCE via a drop casting method that was used for detecting nitrite through the oxidation process. The kinetics of the irreversible oxidation mechanism was studied using scan rate. Amperometry and CV techniques were used for studying the effectiveness of the polyFe_GCE for detecting nitrite at different concentrations. The polyFe_GCE was also used for interference, reproducibility, and stability study. We utilized the proposed sensor further for analyzing nitrite in tap water. The recovery obtained was satisfactory with relatively low value of standard deviation.