芳香酯类三臂液晶化合物的合成与表征

Synthesis and Mesomorphic Properties of Three-Armed Liquid Crystals Containing Aromatic Esters

以间苯三酚为中心,ω [4 (对烷氧基苯甲酰氧基)苯氧甲酰基]戊酸为液晶基元,通过酯化反应合成了芳香酯类三臂液晶化合物·这是一类不同于传统棒状及盘状液晶分子的新型结构液晶化合物·通过红外光谱(IR)、核磁共振谱(1HNMR)对其分子结构进行表征·采用差示扫描量热(DSC)、偏光显微分析(POM)、热重分析(TG)等手段对其液晶性能及热稳定性进行研究·结果表明,此类三臂液晶化合物符合分子设计,热稳定性好,5%热失重温度高于340℃,液晶区间随着分子中末端烷基链的加长而增宽,升、降温过程中均呈现丝状织构,属互变向列相液晶·

A series of novel three-armed liquid crystals based on 1,3,5-trihydroxybenzene as a core and ω-[4-(p-alkoxybenzoloxy)phenoxycarbonyl]valeric acid as mesogenic arms were synthesized by aromatic esterification. They are a new kind of liquid crystals differing from conventional rod-like or discotic molecules. Their chemical structures were confirmed by FTIR and^1HNMR spectra and their mesomorphic phase behavior was investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and thermograrimetric analyzer (TG). The results showed that the three-armed liquid crystals exhibit broad range of liquid crystalline phase at moderate temperature, and the mesomorphic ranges (Δt) broadens with increasing terminal alkyl chains. The temperatures at which the weight loss is up to 5% is higher than 340℃, which revealed that the synthesized three-armed liquid crystals are of high thermal stability. Threadlike texture, typical of nematic phase can be observed in the liquid crystalline state during heating/cooling process.