Bis(tetraethylthiophosphoramidoyl)methylamine as an electrochemical ligand for the simultaneous detection of iron and copper bivalent cations

A new thiophosphoramide-based electrochemical ligand was synthesized and used as a bivalent metallic cation sensor. Electrochemical studies reveal a sensitive detection process toward various cations such as Fe²⁺, Co²⁺, Ni²⁺, Cd²⁺, Cu²⁺ and Ca²⁺. The chelation process was accompanied by dramatic changes in the redox properties of the free ligand. Interestingly, the ligand shows a simultaneous sensing behavior towards iron and copper cations. The oxidation peak potentials of the two complexes can be well separated, allowing sensitive detection. Furthermore, UV–Visible spectra showed redshifts of absorbance bands of the free ligand in the presence of cations due to the coordination of the thiophosphoryl groups. Electrochemical and UV–Visible studies confirmed that the metal-ligand complexes have 1:2 stoichiometry.