In this work, a quantum chemical methods calculationsat B3LYP/6-31G(d) study on the structural and electronic
properties of thienylene-phenylene co-oligomers substituted by donor and acceptor groups is carried out. Eight cooligomers
based on thiophene and phenyleneare studied here.The comparison results of mesomericdonor effect and
mesomeric acceptor effect on the structural and electronic properties of thienylene-phenylene co-oligomers are
discussed. As the electronic properties of this type of conjugatedco-oligomers are governed by their electronic band
gap, we shall also present a comparison among HOMO, LUMO and band gap energies of these different
materials.We conclude that both acceptor and donor side-chains affect the HOMO and LUMO levels significantly.
However, while the acceptor groups stabilize HOMO and LUMO, the donors destabilize them.