The electronic structures of a series of pyrazoline derivatives are investigated by means of quantum chemical calculation methods B3LYP/6-31G and ZINDO-SOS, the semi-experiential method AM1 and PM3 as well as the UV-Vis absorption spectroscopy and cyclic voltammograms (CVs) experiment. The results suggest that the theoretical findings are consistent with the experimental observations, indicating that different constituents could considerably alter the electronic structure, i.e., HOMO level, LUMO level and energy gap. (c) 2004 Elsevier B.V. All rights reserved.