Copper(II) complexes of new biomimetic polydentate amide ligands: a spectroscopic study

Complexes of Cu(II) with N,N′-bis(3-carboxy-1-oxopropanyl)-1,2-ethylenediamine(C10H16N2O6,L1), N,N′-bis(3-carboxy-1-oxopropanyl)-1,2-phenylenediamine(C14H16N2O6,L2), N,N′-bis(2-carboxy-1-oxophenelenyl)-1,2-phenylenediamine(C22H16N2O6,L3) and N,N′-bis(3-carboxy-1-oxoprop-2-enyl)-1,2-phenylenediamine(C14H12N2O6,L4) have been prepared and characterised by elemental analyses, vibrational spectra, magnetic susceptibility measurements, ligand field spectra, EPR spectra, thermal studies and X-ray diffraction spectra. Vibrational spectra indicate coordination of amide and carboxylate oxygens of the ligands giving a MO4 square planar chromophore. Ligand field and EPR spectra support square planar geometry around Cu(II). [Cu(L1)] complex has the maximum activation energy and [Cu(L3)] complex has the minimum activation energy.