烷氧链链长对三环喹唑啉电荷传输性质的影响

Effects of Alkoxy Chain Length on Charge Transfer Properties of Tricycloquinazoline Molecules

使用Marcus模型,在B3LYP/6-31G**水平上研究了四个不同烷氧链链长(n=1,3,5,7)取代的三环喹唑啉衍生物分子的电荷传输性质.计算结果表明,电荷传输矩阵元是影响分子电荷传输的主要因素.4个分子中,随烷氧链长度(n)增大,正、负电荷传输重组能变化范围分别为26～30 KJ/mol和35～47 KJ/mol.正电荷传输矩阵元tA减小超过2倍,电荷传输速率常数kA减小1个数量级.负电荷传输矩阵元tB约增大3倍,电荷传输速率常数kB增大近1个数量级.表明烷氧链增长不利于正电荷传输,有利于负电荷传输.

Discotic liquid crystal molecule of tricycloquinazoline derivatives is used as current carrier transfer material. Theoretical study on the length of alcoxyl soft chain has great influence on the positive and negative charge transfer properties of tricycloquinazoline rigid nuclear. Charge transfer properties of tricycloquinazoline derivative molecules replaced with four dif- ferent alkoxy chain lengths （n = 1, 3, 5, 7） have been investigated through application of semi-classical Marcus model and density functional theory at B3LYP/6-31G^＊＊ level. The calculation results show that charge transfer matrix element is the main factor that affects molecular charge transfer. Of the four molecules, with the increase of alkoxy chain length, the range of positive and negative charge transfer reorganization energy is 26 - 30 kJ/mol and 35 - 47 kJ/mol respectively. Positive charge transfer matrix element tA reduces two times and positive charge transfer rate constant kAdecreases to a lower level in terms of the order of magnitude; negative charge transfer matrix element tB increases three times and negative charge transfer rate constant kB increases to a higher level in terms of the order of magnitude, which indicates that the increase of alkoxy chain length is harmful to positive charge transfer but good for negative charge transfer.