Synthesis of Aminothiophene derivative complexes and electrochemical sensor application for carbofuran pesticide

In this study, a ligand named 2-amino-6-ethyl-4,5,6,7-tetrahydrothieno[2,3-c]pyridine-3‑carbonitrile (ATL), which is an aminothiophene ligand, was synthesized. ATL was used to synthesize ATL-Co(II), ATL-Cu(II), and ATL-Zn(II) complexes. The chemical structures of the complexes were elucidated by spectroscopic methods such as FT-IR, UV–visible, and LC-MS analysis, as well as TG-DTA analysis, magnetic susceptibility measurements, and elemental analysis. Finally, the electrochemical characterization of ATL and the electrochemical sensor application of its complexes was performed. In electrochemical sensor studies, a carbofuran pesticide sensor application was investigated. ATL exhibited an irreversible oxidation peak around 1.0 V. It was observed that ATL-Co(II), ATL-Cu(II), and ATL-Zn(II) complexes behaved similarly to ATL and exhibited an irreversible oxidation peak at the same potential. Carbofuran pesticide was added to the sensor medium using the standard addition method. The changes in peak current with different carbofuran concentrations constituted the data of the amperometric sensor application, and the changes in the peak potential constituted the data of the voltammetric sensor application. Linear working ranges, LOD, and LOQ values were calculated for ATL, ATL-Co(II), ATL-Cu(II), and ATL-Zn(II) complexes, separately. The widest operating range as a voltammetric sensor was achieved with the ATL: 20 μmol L−1 to 350 μmol L−1. The lowest LOD and LOQ values were achieved with the ATL-Co(II) complex for voltammetric detection as 8.8 μmol L−1 and 29.2 μmol L−1, respectively. The lowest LOD and LOQ values were achieved with the ATL-Co(II) complex as 1.6 μmol L−1 and 5.2 μmol L−1 with the amperometric technique, respectively.