ABSTRACT

For the development of self-assembly donor-σ-acceptor (D-σ-A) molecules, a series of D-σ-A low-molecular mass organogelators, consisting of tetrathiafulvalene (D) and cyanobiphenyl (A) connected by a thioalkanoyloxy spacer of varying lengths modified with hydrophobic chains incorporating amide groups on the side, was designed and readily synthesized. Their gelation properties were studied. The results showed that the gelation capability of these compounds was highly dependent on the alkyl chain length in the spacer group and the TTF and cyanobiphenyl units. Derivative 1a with short alkyl chain (n = 4) efficiently gelated in some aromatic solvents, forming opaque organogels. These gelators reacted with F₄TCNQ to form stable charge-transfer complex gels in ethanol. Clear evidence of self-assembled micro/nanoflower, fibrous, or tubular morphologies in gelation state was obtained by scanning electron microscopy. It was found that the molecules adopted lamellar and rectangular columnar molecular packing models in the gel phase by X-ray diffraction. The native gels underwent a reversible gel-sol phase transition upon exposure to external stimuli. The gel-sol transition of the organogel was stimulated by the addition of fluoride anions. Interestingly, all gels showed an irreversible gel-sol transition triggered by TFA and TEA. The formation of flower-like morphologies of TTF-based derivatives in the gel state was observed.

摘要

为了开发自组装供体-σ-受体（D-σ-A）分子，一系列D-σ-A低分子质量有机胶凝剂，由四硫富瓦烯（D）和氰基联苯（A）组成，并通过硫代烷酰氧基连接设计并容易合成了不同长度的间隔基，该间隔基被在侧面结合有酰胺基的疏水链修饰。研究了它们的胶凝性能。结果表明，这些化合物的胶凝能力高度依赖于间隔基团中的烷基链长度以及TTF和氰基联苯单元。具有短烷基链（n = 4）的衍生物1a在某些芳族溶剂中有效地胶凝，形成不透明的有机凝胶。这些胶凝剂与F ₄反应TCNQ在乙醇中形成稳定的电荷转移复合物凝胶。通过扫描电子显微镜获得了凝胶状态下自组装的微/纳米，纤维状或管状形态的清晰证据。通过X射线衍射，发现分子在凝胶相中采用层状和矩形柱状分子堆积模型。天然凝胶在暴露于外部刺激后经历了可逆的凝胶-溶胶相变。通过添加氟阴离子来刺激有机凝胶的凝胶-溶胶转变。有趣的是，所有凝胶均显示出由TFA和TEA触发的不可逆的凝胶-溶胶转变。观察到在凝胶状态下基于TTF的衍生物的花状形态的形成。