新型偶氮苯基团凝胶因子的合成及其光响应行为

Synthesis and Photo-responsive Properties of Novel Gelators Based on Azobenzene

设计合成了两种新型偶氮苯类凝胶因子Azo-1和Azo-2,两者均能在多种有机溶剂中形成稳定凝胶.利用扫描电子显微镜观察凝胶的显微结构,发现随着溶剂极性增大,凝胶纤维束直径有所增大.采用Hansen溶度参数对凝胶性能进行分析,形成凝胶的溶剂集中分布在Hansen空间的一定区域,凝胶的Tgel主要受色散参数的影响.通过紫外-可见吸收光谱考察了凝胶因子在稀溶液及凝胶状态的光谱性质,在溶液中Azo-1的偶氮苯基团的光致反-顺异构转变速度远快于Azo-2,仅Azo-1在四氢呋喃和三氯乙烯等溶剂中表现出光致凝胶-溶胶的转变.光照前后的凝胶微观形貌结构发生显著的改变.通过Hansen溶度参数分析发现,能够发生光致相转变的溶剂在Hansen空间基本处在同一直线上.

Two novel gelators Azo-1and Azo-2based on azobenzene were designed and synthesized.The two gelators can form gel in the multiple organic solvents.The SEM images of the xerogels showed the diameter of the gel fibers increased with the increase of polar organic solvents.Further investigation on gelation behavior based on Hansen solubility parameters of solvents revealed that most of solvents could form gels cluster in a certain region in Hansen space,and the value Tgel of gel was influenced by the dispersion parameters.The spectra character of the gelator in gel phase and sol phase was examined by UV-Vis spectra.The azobenzene group of Azo-1in solution had a much faster trans-cis photoisomerization reaction than that of Azo-2.The azobenzene groups of Azo-1in the gel in certain solvents performed the expected trans-cis photoisomerization with a gel to sol phase upon irradiation of UV light.An obvious change of morphologies occurred in gel phase and sol phase.The three solvents that could produce photo-induced phase transition lie on the same line in Hansen space.