EFFECTS OF BRIDGING GROUPS ON ELECTRONIC-STRUCTURES OF CONJUGATED CYCLIC POLYMERS

Theoretical investigation was performed to elucidate effects of the br idging groups (X) on the bandgaps of conjugated cyclic polymers. In ad dition to heterocyclic polymers such as polythiophene, polypyrrole and polyfuran, the polymers concerned in this study include the conjugate d cyclic polymers which contain bridging groups of YZ(2) forms (CH2, C F2, SiH2 and SiF2) or Y=Z forms (C=CH2, C=O and C=S). Geometrical stru ctures of the polymers were optimized through semiempirical band calcu lations with AM1 Hamiltonian. A modified extended Huckel method was em ployed to obtain electronic properties of the polymers. Effects of the bridging groups on bandgaps of the polymers were analyzed in terms of geometrical relaxations and electronic perturbations.