Synthesis and Cyclic Voltammetry Studies of Copper Complexes of Bromo- and Alkoxyphenyl-Substituted Derivatives of Tris(2-pyridylmethyl)amine: Influence of Cation-Alkoxy Interactions on Copper Redox Potentials.

A combination of host-guest chemistry and coordination chemistry in the design of electrochemical sensors for alkali metal and ammonium ions is described. The sensor molecules are coordination complexes between a copper ion and a functionalized tripodal ligand. Upon presentation of the ion to the sensor molecule, a shift in the redox potential of the copper ion occurs. In the course of the study, three new alkoxyphenyl-substituted derivatives of the ligand tris(2-pyridylmethyl)amine (TPA) were prepared and characterized. The synthesis of the new ligands involved the preparation of bromopyridyl-TPA derivatives followed by Suzuki coupling with substituted phenylboronic acids. Cyclic voltammetry studies of copper complexes of the ligands indicated that steric effects played a dominant role in the overall determination of the copper redox couple. Studies of the alkoxyphenyl ligands indicated that small but reproducible changes in the copper redox couple occurred upon presentation of a guest cation that would be expected to form a complex with the copper-ligand complex.