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

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 different 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 kA decreases 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.