光响应偶氮苯类小分子凝胶因子的合成及性能

Synthesis and Properties of Photoresponsive Organogels Based on Azobenzene Derivatives

合成了3个系列各6类的偶氮苯衍生物1a^6a,1b^6b和1c^6c.凝胶性能测试结果表明,这些化合物均能在多种极性或非极性有机溶剂中形成凝胶.运用扫描电子显微镜和核磁共振波谱仪对代表性化合物4b形成的凝胶结构和成胶驱动力进行了分析.化合物4a^4c形成的凝胶在紫外光和可见光照射下,能够发生凝胶-溶胶的相互转化.计算了溶剂和凝胶因子的梯氏参数,利用梯氏三角图分析了凝胶测试结果,发现凝胶因子在溶剂中的4种行为(溶液、半凝胶、凝胶和沉淀)分别分布在三角图的不同区域;在凝胶区域,溶剂与凝胶因子之间的距离反映了凝胶的热稳定性,距离越远表示凝胶的热稳定性越好.

Eighteen azobenzene derivatives, 1a-6a, 1b-6b and 1c-6c, were synthesized and their gelation behaviors were tested. The synthesized azobenzenes readily formed stable gels in many polar or apolar organic solvents. As the representative, the structures of gels from compound 4b and the driving force of the gel formation were investigated by SEM and ^1H NMR. The photoresponse of the gels from compounds 4a-4c was studied and they all showed gel-sol transition under UV light irradiation while sol-gel transition in visible light radiation. Teas parameters of the solvents and gelators were systematically calculated and presented in the Teas plots. The results show that the four gelation behaviors（ solution, partial gelation, gelation and precipitation） are located in different regions respectively. In the region of gelation, the distance between the solvent and the gelator reflects the thermal stability of the gel, the farther the distance is, the better the thermal stability of the gel will be.