新型环三藜芦烃衍生物的合成及其热致液晶行为的研究

设计了先关环再衍生的方法,合成了系列外围含不同反应性官能团的新的环三藜芦烃(CTV)衍生物.利用1HNMR、13C-NMR、元素分析、质谱等对合成的CTV衍生物进行了结构表征.研究表明,分子间作用力增大会导致CTV衍生物的热致液晶性减弱,结晶性增强.合成的CTV-A具有热致液晶性；CTV-D和CTV-E由于氨基的存在产生了较强的分子间氢键作用,既形成了热致液晶态,又发生冷结晶；而CTV-B和CTV-C由于含有羧基、羰基、羟基或氨基等,分子间作用力强,只出现冷结晶,不能形成热致液晶.研究发现,通过外围基团的分子设计,调节氢键能力或柔性间隔基,可调节分子间作用力和熵的大小,从而控制CTV衍生物的热致液晶性.

Synthesis and Thermotropic Liquid Crystallinity Study of Novel Cyclotriveratrylene Derivatives

A novel series of cyclotriveratrylene derivatives(named as CTV-A,CTV-B,CTV-C,CTV-D and CTV-E) were synthesized by cyclization-derivatization method,which was different from traditional synthesis route as monomer derivatization first,then cyclization.Chemical structure of these derivatives was characterized by NMR,elemental analysis and mass spectrometry.Thermotropic liquid crystallinity was studied by the combination of DSC and thermal polarized optical microscopy(TPOM).It was found that the enhancement of intermolecular interaction of CTV derivatives led to their liquid crystallinity weakened,but crystallinity enhanced.Compared with CTV-A,the melting temperature(Tm) and clear temperature(Tc) of CTV-D and CTV-E both increase resulted by hydrogen bonding between amino group and carbonyl group;and the flexible spacer —CH2—CH2— in CTV-E makes its Tm decreased,leading to a widest liquid crystal temperature-range.However,CTV-B and CTV-C are not thermotropic liquid crystal but only crystalline compounds,due to their strong intermolecular interaction caused by the introduction of carboxyl and hydroxyl groups.Therefore,the liquid crystallinity of CTV derivatives can be controlled by the tuning of intermolecular interaction and conformation entropy through rational molecular design.