聚并苯和取代聚并苯电子性质的量子化学研究

准一维聚并苯体系是一类典型的梯形结构有机导体材料．采用量子化学一维紧束缚自洽场晶体轨道ＣＮＤＯ／２　方法，研究了顺、反式聚并苯和取代聚并苯的结构、能量和电子布居．计算了甲基、甲氧基、氯和羟基取代聚并苯的电子能带，与聚并苯进行了分析比较．结果表明：（１）单取代使对称性明显降低，对聚并苯的能带结构影响较大，使能隙值普遍增大，导电性能降低．（２）双取代虽使电荷重新分布，但基本保持聚并苯自身结构特征．取代聚并苯与聚并苯比较能隙值变化不大．对于不同的取代基影响规律不同．对位双取代与间位双取代也表现出差异．（３）顺式和反式结构聚并苯的电子性质略有差异，取代后变化较大．

Quantum Chemistry Studies on the Electronic Properties of Polyacene (PA) and its Derivatives

Quasi-one dimension polyacene (PA) is a kind of organic conducting material with typical ladder shape structure. In this paper, the structure, energy and charge distribution of trans-and cis-PA and its derivatives have been studied by using quantum chemical CNDO/2-CO method.The energy bands of PA substituted with methyl, methoxy, chlorine and hydroxy have been calculated and compared with that of PA respectively. The results show:(1) With the extension of PA from quasi-one dimension to two dimensions,the energy of substituted PA decreases, which illustrated that the changing rule of stability of substituted PA is analogous to that of PA, that is, substitution have no effect on the stability changing rule when the PA molecular extend to two dimensions. (2) Substitution did not change the energy gap evidently.(3) The energy Gap values of bisubstituted PA increased with the molecular width and showed vibration trend. This trend varies with substitution group.