State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
J Am Chem Soc. 2021 Dec 8;143(48):20368-20376. doi: 10.1021/jacs.1c09958. Epub 2021 Nov 19.
The manipulation of covalent bonds could be directed toward degradable, recyclable, and sustainable materials. However, there is an intrinsic conflict between properties of stability and degradability. Here we report light-controlled formation/scission of three types of covalent bonds (C-N, C-O, and C-S) through photoswitching between equilibrium and nonequilibrium states of dynamic covalent systems, achieving dual benefits of photoaddressable stability and cleavability. The photocyclization of dithienylethene fused aldehyde ring-chain tautomers turns on the reactivity, incorporating/releasing amines, alcohols, and thiols reversibly with high efficiency, respectively. Upon photocycloreversion the system is shifted to kinetically locked out-of-equilibrium form, enabling remarkable robustness of covalent assemblies. Reaction coupling allows remote and directional control of a diverse range of equilibria and further broadens the scope. Through locking and unlocking covalent linkages with light when needed, the utility is demonstrated with capture/release of bioactive molecules, modification of surfaces, and creation of polymers exhibiting tailored stability and degradability/recyclability. The versatile toolbox for photoswitchable dynamic covalent reactions to toggle matters on and off should be appealing to many endeavors.
共价键的操纵可以定向于可降解、可回收和可持续的材料。然而，稳定性和可降解性之间存在内在冲突。在这里，我们通过动态共价体系平衡态和非平衡态之间的光致转换，报告了三种类型的共价键（C-N、C-O 和 C-S）的光控形成/断裂，实现了光可寻址稳定性和可裂解性的双重益处。二噻烯-乙烯缩醛环链互变异构体的光环化反应开启了反应性，分别以高效率可逆地结合/释放胺、醇和硫醇。光环化回复时，体系转变为动力学锁定的非平衡形式，使共价组装具有显著的坚固性。反应偶联允许对各种平衡进行远程和定向控制，并进一步拓宽了范围。通过按需用光锁定和解锁共价键，该方法在生物活性分子的捕获/释放、表面修饰以及创建具有定制稳定性和可降解性/可回收性的聚合物方面得到了证明。这种用于光开关动态共价反应的多功能工具包，可用于打开和关闭物质，应该会吸引许多人的关注。
