The synthesis and characterization of a new dioxime ligand, (H,L), (III) and its trinuclear copper(II) complex, [Cu3L2(H2O)(2)](ClO4)(2), (V) is described. IR spectra show that the ligand acts in a tetradentate manner and coordinates N-4 donor groups of H,L to copper(II) ion. The structure of the metal chelate is clarified with the help of elemental analysis, magnetic moment, conductometric and spectroscopic measurements. The optical absorption studies reveal that the transition is direct with band gap energy values are calculated. The optical constants such as refractive index and dielectric constant of the compound were determined. The refractive index dispersion curves of the films obey the single-oscillator model and oscillator parameters. Optical dispersion parameters E-0 and E-d developed by Wemple-DiDomenico were calculated. (c) 2006 Elsevier B.V. All rights reserved.