基于胆固醇的新型小分子胶凝剂的合成与胶凝行为

Synthesis and Gelation Properties of Cholesterol-Based New Low-Molecular-Mass Gelators

设计合成了3种以丙二胺为连接臂（L）、苯环为A单元的A（LS）2型双胆固醇（S）类小分子胶凝剂： 化合物1（邻位）, 化合物2（间位）和化合物3（对位）, 考察了其在30种溶剂中的胶凝行为. 结果表明, 苯环取代位置的不同对化合物的胶凝性质有决定性影响. 就胶凝溶剂的数量来讲, 对位取代的化合物3的胶凝能力明显高于邻位和间位取代的化合物1和2. 此外, 化合物2和3可以形成5个室温胶凝体系, 且化合物3/二甲苯凝胶透明、柔韧,以至于可以形成超分子薄膜. 傅里叶变换红外（FTIR）光谱和核磁共振氢谱（1H NMR）研究表明, 胶凝剂分子之间的氢键和π-π堆积作用在凝胶形成过程中发挥了一定的作用. X射线衍射（XRD）研究表明在化合物1/苯凝胶中, 胶凝剂分子聚集为六方堆积结构, 进而形成贯穿整个凝胶体系的网络结构.

Three novel dimeric cholesteryl-based low-molecular-mass gelators （LMMGs）, which have the structure A（LS）2, were designed and synthesized. In the structures, 1,3-diaminopropane is a linker （L）, A is a benzene ring, and S is cholesteryl. According to the positions of the substituents on the benzene ring, the as-prepared compounds are denoted by 1 （o-position）, 2 （m-position）, and 3 （p-position）, respectively. Their gelation properties were evaluated in 30 solvents. It was revealed that the relative positions of the two cholesteryl moieties on the benzene ring play a crucial role in the gelation behaviors of the compounds. In terms of the number of solvents gelled by the tested compounds, compound 3 is a more versatile gelator than compounds 1 and 2; compounds 2 and 3 can form five gels at room temperature. Furthermore, the compound 3/xylene gel is transparent and flexible, and forms a supramolecular film in the wet state. Fourier- transform infrared （FTIR） spectroscopy and IH nuclear magnetic resonance （IH NMR） spectroscopy studies demonstrated that intermolecular hydrogen bonding and TT- TT stacking among the molecules of the gelators play important roles in the gelation process. X-ray diffraction （XRD） analysis showed that the aggregate of compound 1 from its benzene gel adopts a hexagonal packing mode as the elementary structure of the gel networks.