【摘要】 设计、合成了一系列新型低聚噻吩衍生物N ,N′ 双烷烃基 5 ,5″ 二溴基 2 ,2′ :5′ ,2″ 三噻吩 4,4″ 二酰胺 [N ,N′ dialkyl 5 ,5″ dibromo 2 ,2′ :5′ ,2″ terthiophene 4,4″ dicarboxamide] (DNCnDBr3T ,n =5 ,8,16,18) .示差扫描量热法 (DSC)测定的结果及偏光光学显微镜观察的结果显示 ,DNC18DBr3T ,DNC16DBr3T ,DNC8DBr3T具有近晶A形液晶性质 ,DNC5DBr3T不具有液晶性质 .为了探讨分子间氢键对液晶形成的影响 ,设计、合成了新型低聚噻吩衍生物 4,4″ 双烷烃酯 5 ,5″ 二溴基 2 ,2′ :5′ ,2″ 三噻吩 [4,4″ bis(alkyloxycarbonyl) 5 ,5″ dibromo 2 ,2′ :5′ ,2″ terthiophene] (DOCnDBr3T ,n =5 ,8,16,18) .测定和观察的结果发现 ,DOCnDBr3T (n =5 ,8,16,18)不具有液晶的性质 .这个结果表明 ,酰胺基的存在对于液晶的形成起着重要的作用 .测定DNC18DBr3T在结晶状态和液晶状态下的红外光谱 ,进一步证实了部分分子间氢键对于液晶的形成起着重要的作用更多还原

【Abstract】 With the aim of developing new oligothiophene based liquid crystals involving hydrogen bonding, new terthiophene derivatives containing an alkylamide group, N,N′ dialkyl 5,5″ dibromo 2,2′:5′,2″ terthiophene 4,4″ dicarboxamide (DNC n DBr3T, n =5, 8, 16, 18), were designed and synthesized, and their thermal behaviors were examined. While DNC n DBr3T compounds with n =8, 16, 18 were found to form smectic A phase, DNC 5DBr3T did not form liquid crystal phase. In addition to liquid crystal behavior, crystal polymorphism was also observed for DNC 16 DBr3T . It is shown that the alkyl chain length greatly affects liquid crystal phase formation. The absence of liquid crystallinity in the corresponding ester derivatives suggests that intermolecular hydrogen bonding plays a role in the formation of liquid crystal phase in the DNC n DBr3T system.更多还原