T-型氢键液晶复合物的制备与液晶行为

以不具有液晶行为的2,6-二[N,N′-二-(4-烷基苯甲酰基)]氨基吡啶(A系列)和4-正烷氧基苯甲酸(D系列)作为氢键液晶复合物的单体,组装成T-型氢键液晶系列复合物(AmDn)。用红外光谱对其结构进行了表征,用DSC及偏光显微方法对其液晶行为进行了研究。结果表明:所合成的21种复合物分子间存在氢键且都具有向列相。通过调整2,6-二[N,N′-二-(4-烷基苯甲酰基)]氨基吡啶分子上柔性烷基的长度和极性,可以有效地调节它与4-烷氧基苯甲酸形成的氢键复合物的液晶相变温度以及液晶态的稳定性;增加2,6-二[N,N′-二-(4-烷基苯甲酰基)]氨基吡啶分子上柔性烷基的长度,其复合物AmDn的液晶相温度范围趋于变窄,清亮点逐渐下降,其液晶态稳定性也逐渐下降;以2,6-二[N,N′-二-(4-烷基苯甲酰基)]氨基吡啶分子替代2,6-二[N,N′-二-(4-烷氧基苯甲酰基)]氨基吡啶分子,可以降低分子的极性,使其单体的熔点及其氢键复合物AmDn的相变温度下降。

Preparation and Liquid Crystalline Phase of T-Shaped Hydrogen-Bonded Liquid Crystal Complexes

2,6-Bis(4-alkylbenzoyl) aminopyridine(A series),no liquid crystalline phase,and(4-alkoxybenzoic) acids(D series) were selected as the monomers of hydrogen-bonded liquid crystals to form T-shaped hydrogen-bonded liquid crystal complexes(AmDn).As verified by infrared spectrum, there existed intermolecular hydrogen bonds,and the liquid crystalline behavior of the complexes was studied by DSC and polarizing microscopy.The study indicates that the 21 synthesized hydrogen-bonded complexes are all nematic liquid crystals,and by means of adjusting the length and polarity of the soft alkyl connecting 2,6-bis(4-alkylbenzoyl) aminopyridine molecular,the phase transition temperature and stability of the hydrogen-bonded liquid crystal complexes formed by 2, 6-bis(4-alkylbenzoyl) aminopyridine and 4-alkoxybenzoic acid can be effectively adjusted.The experiment show when the alkyl of 2,6-bis(4-alkylbenzoyl) aminopyridine is lengthened,the range concerning the phase transition temperature of its complexes(AmDn) tended to be narrow,the clearing point decrease gradually and so does the stability of its liquid crystalline phase.By adopting 2,6-bis(4-alkylbenzoyl) aminopyridine instead of 2,6-bis(4-alkoxybenzoyl) aminopyridine,the polarity of the molecular could be lowered,which result in melting point of the monomer and phase transition temperature of the hydrogen-bonded liquid crystal complexes(AmDn) decrease.