【摘要】 采用DFT/B3LYP方法对低聚物(p-P)2n、(m-P)2n、(m-P1)n和(m-P2)n(n=1￣4)体系进行了全优化,并用ZINDO,TD-DFT方法计算其吸收光谱性质.分析了各系列HOMO-LUMO能隙、最大吸收波长随n递增的变化规律.根据低聚物的上述结果外推得到聚合物的性质,并由此计算了聚合物的有效共轭长度(ECL).由于间位连接方式的影响,削弱了间位聚苯及其衍生物的有效共轭程度,与对位聚苯比较,能带带隙变宽,吸收光谱蓝移约130nm.更多还原

【Abstract】 Geometrical optimization was performed on the oligomers of (p-P)2n, (m-P)2n, (m-P1)n, and (m-P2)n(n=1~4) using DFT/B3LYP method. The absorption spectra were calculated by ZINDO and TD-DFT. The rules for the variation of the HOMO-LUMO energy gap and the increasing of maximal absorption wavelength with "n" were analyzed. Based on these results, the corresponding properties of the polymers were obtained by extrapolation. ECL (effective conjugated length) of the polymers was calculated by the regressive expression. ECL was shortened greatly due to the meta-linked fashion of poly(m-phenylene). Compared with poly(p-phenylene), poly(m-phenylene) and derivatives hold wider band gap, and its maximal absorption wavelength blue shifted about 130 nm.更多还原