Abstract
In order to reduce the number of hydrogen bonds in biamide derivatives, one amide group in N-(4-cetyloxybenzoyl)-N'-(4'-nitrobenzoyl) hydrazine (C16-NO2) was replaced by a Schiff base group, forming N-(4-cetyloxybenzoyl)-N'-(4'-nitrobenzylidene) hydrazine (C16-Sch). Computational study on the molecular structure at B3LYP/6–311+G** level revealed that the molecular geometry of C16-NO2 could be well retained by C16-Sch. In addition, C16-Sch exhibited the same mesophase structure (SmA1) as C16-NO2, and the hydrogen bonding was demonstrated to be still interacting in the mesophase. However, compared to C16-NO2, the mesophase stability of C16-Sch is dramatically decreased by the reduction of the number of hydrogen bonds, providing direct evidence that intermolecular hydrogen bonding plays an important role in stabilising the smectic phase.
Acknowledgements
This work was supported by the National Science Foundation of China (50873044, 51073071, 20973076 and 21003057) and Jilin University (200903014).