光化学
烯胺
亚胺
共价键
光异构化
分子内力
反应性(心理学)
材料科学
发色团
光催化
分子开关
化学
化学物理
分子
有机化学
异构化
催化作用
医学
替代医学
病理
作者
Zheng Lin,Shujing Liu,Weijun Weng,Changchun Wang,Jia Guo
出处
期刊:Small
[Wiley]
日期:2023-10-24
卷期号:20 (10)
标识
DOI:10.1002/smll.202307138
摘要
Covalent organic frameworks (COFs) offer a desirable platform to explore multichoromophoric arrays for photocatalytic conversion. Symmetric arrangement of choromophoric modules over π-extended frameworks enhances exciton delocalization while impairing excitation density and accordingly photochemical reactivity. Herein, a photoisomerization-driven strategy is proposed to break the excited-state symmetry of ketoenamine-linked COFs with multichoromophoric arrays. Incorporating electron-withdrawing benzothiadiazole facilitates the ultrafast excited-state intramolecular proton transfer (ESIPT) from enamine to keto within 140 fs, resulting in partially enolized COF isomers. The hybrid linkages containing imine and enamine bonds at the node of framework alter the symmetry of electronic structure and enforce the photoinduced charge separation. Increasing the imine-to-enamine ratio further promotes the electron transferred number in a long range, thereby affording the optimum photocatalytic hydrogen evolution rate. This work put forward an ESIPT-induced photoisomerization to build a symmetry-breaking COF with weakened exciton effect and enhanced photochemical reactivity.
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