Spectroscopic studies of some copper(II) complexes with amino acids

Copper-amino acids complexes in aqueous solution: [Cu-(L-1)(2)]center dot H2O(1), (L-1 = methionine), [Cu-(L-2)(2)]center dot H2O (2), (L-2 = phenylalanine) and [Cu(L-3)(2)](3), (L-3 = triptophan) were synthesized and characterized by means of elemental, thermal and IR, UV-Vis and EPR spectroscopic investigations. The IR spectra show that amino acids act as bidentate ligands with coordination involving the carboxylic oxygen and the nitrogen atom of the amino group. The nu(C=O) and delta(N-H) vibrations are shifted toward higher (for 1 and 2) and lower-wave numbers for 3. Visible electronic and Powder EPR spectra at room temperature are typical for monomeric species with square-planar local symmetry around the metal ion. (c) 2006 Elsevier B.V. All rights reserved.