Meiji Pharmaceutical University.
Chem Pharm Bull (Tokyo). 2022;70(6):443-447. doi: 10.1248/cpb.c22-00134.
Urea derivatives 1 and 2, synthesized from adenosine, were designed as low-molecular-weight gelators. Hydrophobic groups have been introduced into all or part of the hydroxy groups of the hydrophilic ribose moiety of 1 and 2 to control the solvophilicity of the molecules and their aggregates. Compound 2 selectively formed supramolecular gels in halogenated solvents such as chloroform and 1,2-dichloroethane. The supramolecular gel of 2 and chloroform was thermally stable and its gel-to-sol phase transition temperature was higher than the boiling point of chloroform. The physical properties of the supramolecular gel were investigated by determining its viscoelastic properties using a rheometer. The supramolecular gel realized multiple stimuli-responsive reversible gel-sol phase transitions. The supramolecular gel showed reversible phase transition by repeated warming-cooling cycles accompanying with the gel-sol transitions. The supramolecular gel could undergo five repeated mechano-responsive gel-sol transitions. Gel-to-sol phase transition could also be achieved by adding various anions to the supramolecular gel, such as tetrabutylammonium fluoride. Regelation was realized by adding boron trifluoride etherate to the fluoride ion containing sol. Addition of methanol to the supramolecular gel also induced gel-to-sol phase transition. Regelation was realized by adding molecular sieves 4 Å to the suspension.
尿素衍生物 1 和 2 是由腺苷合成的，被设计为低分子量凝胶剂。在 1 和 2 的亲水性核糖部分的所有或部分羟基中引入了疏水性基团，以控制分子及其聚集体的亲溶剂性。化合物 2 选择性地在卤代溶剂（如氯仿和 1,2-二氯乙烷）中形成超分子凝胶。2 和氯仿的超分子凝胶热稳定，其凝胶-溶胶相转变温度高于氯仿的沸点。使用流变仪测定其粘弹性来研究超分子凝胶的物理性质。超分子凝胶实现了多种刺激响应的可逆凝胶-溶胶相转变。超分子凝胶通过伴随凝胶-溶胶转变的反复加热-冷却循环实现了可逆的相转变。超分子凝胶可以进行五次重复的机械响应凝胶-溶胶转变。向超分子凝胶中加入各种阴离子，如四丁基氟化铵，也可以实现凝胶-溶胶相转变。向含有氟离子的溶胶中加入三氟化硼乙醚可以实现再凝胶化。向超分子凝胶中加入甲醇也会诱导凝胶-溶胶相转变。向悬浮液中加入 4Å分子筛可以实现再凝胶化。
