Theoretical Studies of the Influence of Intermolecular Interactions on the Photophysical Properties of Poly (p-phenylene-2,6-benzobisoxazole) (PBO)

The photo-physical properties of hetero-aromatic(poly(p)-phenylene-2, 6-benzobisoxazole)(PBO) were studied by a quantum chemistry calculation method AM1-ZINDO/CI.The interfacial action between two conjugated planar structures of the PBO molecules affected the transition of the electrons on the fronted molecular orbit,resulting in a red shift in the electronic spectrum of the aggregated polymer compared to that of the theoretical mono-molecular chain.The analog computation of the PBO congeries molecular model,which is composed of three repeated units,shows that the interfacial action between two conjugated planar structures of the PBO molecules makes the maximum(absorption)-peak of electronic spectrum a red shift from 383.06 nm to 407.19 nm.Based on the homologous linear rule,the maximum(absorption)-peak of the electronic spectrum of the PBO molecule is deduced to the 425.33 nm.The spectrum characteristic of the electronic spectrum of the PBO congeries is explained from its intrinsic structure.