School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.
Org Biomol Chem. 2018 Oct 31;16(42):7871-7877. doi: 10.1039/c8ob01944d.
The occurrence of dynamic covalent reactions only requires relatively low activation energy, which allows both the forward and reverse reactions to proceed under mild conditions. Here, we report the design and synthesis of amphiphilic maleimide-furan adducts, where hydrophobic maleimide-based and hydrophilic furan-based moieties were connected by reversible dynamic covalent bonds. The Diels-Alder addition reactions of maleimide-furan adducts are simple, efficient, clean, and reversible without catalysts and side reactions, and occur under mild conditions. Single crystal X-ray diffraction revealed that the length of the dynamic covalent bonds is 1.56 Å, which is longer and weaker than for normal covalent bonds. The cleavage and reformation process of the dynamic covalent bonds was monitored by 1H NMR and fluorescence spectroscopy. 1H NMR spectroscopy revealed that the furan moieties of these new maleimide-furan amphiphiles can be exchanged in mixing systems due to dynamic Diels-Alder reactions; thus, two new maleimide-furan compounds can be transformed into each other. The maleimide-furan amphiphiles displayed reversible fluorescence ON/OFF behaviours and interesting H-bonding driven supramolecular assembly.
动态共价反应的发生只需要相对较低的活化能，这使得正、逆反应都能在温和的条件下进行。在这里，我们报告了两亲性马来酰亚胺-呋喃加合物的设计和合成，其中疏水性马来酰亚胺基和亲水性呋喃基部分通过可逆动态共价键连接。马来酰亚胺-呋喃加合物的 Diels-Alder 加成反应简单、高效、清洁、无催化剂和副反应，在温和条件下进行。单晶 X 射线衍射表明，动态共价键的长度为 1.56 Å，比普通共价键长且弱。通过 1H NMR 和荧光光谱监测了动态共价键的断裂和重组过程。1H NMR 光谱表明，由于动态 Diels-Alder 反应，这些新的马来酰亚胺-呋喃两亲物中的呋喃部分可以在混合体系中交换，因此两种新的马来酰亚胺-呋喃化合物可以相互转化。马来酰亚胺-呋喃两亲物表现出可逆的荧光 ON/OFF 行为和有趣的氢键驱动超分子组装。
