Synthesis, structural and electrochemical properties of a new family of amino-acid-based coordination complexes.

Metalloproteins involved in oxidation-reduction processes in metabolism are fundamental for the wellbeing of every organism. The use of amino-acid-based compounds as ligands for the construction of biomimetic coordination systems represents a promising alternative for the development of new catalysts. Herein is presented a new family of copper, zinc and nickel coordination compounds, which show four-, five- and six- coordination geometries, synthesized using Schiff base ligands obtained from the amino acids L-alanine and L-phenylalanine. Structural analysis and property studies were performed using single-crystal X-ray diffraction data, spectroscopic and electrochemical experiments and DFT calculations. The analysis of the molecular and supramolecular architectures showed that the non-covalent interactions developed in the systems, together with the identity of the metal and the amino acid backbone, are determinants for the formation of the complexes and the stabilization of the resultant geometries. The CuII complexes were tested as candidates for the electrochemical conversion reduction of nitrite to NO, finding that the five-coordinate L-phenylalanine complex is the most suitable. Finally, some insights into the rational design of ligands for the construction of biomimetic complexes are suggested.