Structural analysis of a Cu(II) complex with a novel macrocyclic polyamine in aqueous solution

A macrocyclic ligand modified with pendant arm, N-mono(2-aminoethyl)-1,4,8,11-tetraazacyclotetradecane (maec), and its copper(II) complex have been synthesized and characterized. The structure of the copper(II) complex in aqueous solutions at pH 2-6 was determined by extended X-ray absorption fine structure (EXAFS). The EXAFS spectra were analyzed using an FEFF8. It was difficult to determine the coordination geometry of copper(II) ion solely from EXAFS analysis. For that reason, X-ray absorption near-edge structure (XANES) spectroscopy was combined with full multiple scattering calculations (FEFF 8.20) for a series of four-, five- and six-coordination models to determine the coordination geometry.