Abstract
Three kinds of benzoic acid compounds were synthesized and characterized; the corresponding symmetric hydrogen‐bonded liquid crystalline complexes based on these benzoic acid compounds and 4,4′‐bipyridine (BPy) were then prepared. The existence of the hydrogen bonds was verified by Fourier transform infrared spectroscopy. The liquid crystalline properties of the complexes were demonstrated by polarizing microscopy and differential scanning calorimetry. 4‐Allyloxy‐2‐fluorobenzoic acid and two fluorinated hydrogen‐bonded complexes exhibited only nematic phases, whereas the non‐fluorinated complex showed both smectic and nematic phases. The clearing points and mesophase thermal range of the complexes decreased with increasing number of lateral fluorine atoms on the rigid core.
Acknowledgements
This research was supported by the National High Technology 863 Program of China under Grant No. 2003AA327050 and the Major Project of Ministry of Education of the People's Republic of China under Grant No.104187.