In this paper a combined experimental and quantum chemical study of two co-polymers, derived from poly(phenylene vinylene), referred to as PPV-ether and C1-4PPV-ether, is presented. First, the geometries of these co-polymers were fully optimized. In fact, semiempirical, ab initio and density functional theory (DFT) have been used to investigate the ground-state properties of these co-polymers. Then, the electronic properties, lying in the excitation between the highest occupied molecular orbitals (HOMO) and the lowest unoccupied molecular orbitals (LUMO), the transition eigenvalues, the density of states together with other relevant physical quantities, were investigated. Moreover, the vibrational properties and the force constants are determined. In fact, the calculated results have well reproduced the available experimental data in which the pattern of dialkoxy-substitution is found to have a large effect. (c) 2005 Elsevier Ltd. All rights reserved.