南京大学雷建平研究团队报道了引导电化学发光的网状棘轮。相关研究成果于2024年6月5日发表在《美国化学会杂志》。

电化学发光（ECL）涉及电化学氧化还原中间体之间的电荷转移，以产生用于发光的激发态。确保电荷转移的精确控制对于分析ECL基本原理至关重要，然而如何实现传统发射器的精确控制的指导方针尚未探索。分子棘轮提供了一种潜在的解决方案，因为它们能够实现能量或化学物质的定向转移，同时阻碍反向运动。

该文中，研究人员设计了10对亚胺基共价有机框架作为网状棘轮，以精细地操纵网状内电荷转移，从而指导电能和化学能的ECL转导。将供体和受体（D–A）方向与亚胺偶极对齐有效地促进了电荷迁移，而反转D–A方向则阻碍了电荷迁移。值得注意的是，电荷转移方向性的棘轮效应随着D–A对比度的增加而增强，导致ECL效率显著提高了680倍。

此外，偶极控制的激子结合能、电子/空穴衰变动力学和飞秒瞬态吸收光谱，确定了ECL转导过程中电子从网状棘轮的N端向C端的转移趋势。研究发现了ECL效率与偶极差之间的指数相关性。

研究工作为操纵电荷转移和设计下一代电化学器件提供了一种通用方法。

附：英文原文

Title: Reticular Ratchets for Directing Electrochemiluminescence

Author: Rengan Luo, Xiao Luo, Haocheng Xu, Sushu Wan, Haifeng Lv, Beier Zou, Yufei Wang, Tianrui Liu, Chuang Wu, Qizhou Chen, Siqi Yu, Pengfei Dong, Yuxi Tian, Kai Xi, Shuai Yuan, Xiaojun Wu, Huangxian Ju, Jianping Lei

Issue&Volume: June 5, 2024

Abstract: Electrochemiluminescence (ECL) involves charge transfer between electrochemical redox intermediates to produce an excited state for light emission. Ensuring precise control of charge transfer is essential for decoding ECL fundamentals, yet guidelines on how to achieve this for conventional emitters remain unexplored. Molecular ratchets offer a potential solution, as they enable the directional transfer of energy or chemicals while impeding the reverse movement. Herein, we designed 10 pairs of imine-based covalent organic frameworks as reticular ratchets to delicately manipulate the intrareticular charge transfer for directing ECL transduction from electric and chemical energies. Aligning the donor and acceptor (D–A) directions with the imine dipole effectively facilitates charge migration, whereas reversing the D–A direction impedes it. Notably, the ratchet effect of charge transfer directionality intensified with increasing D–A contrast, resulting in a remarkable 680-fold improvement in the ECL efficiency. Furthermore, dipole-controlled exciton binding energy, electron/hole decay kinetics, and femtosecond transient absorption spectra identified the electron transfer tendency from the N-end toward the C-end of reticular ratchets during ECL transduction. An exponential correlation between the ECL efficiency and the dipole difference was discovered. Our work provides a general approach to manipulate charge transfer and design next-generation electrochemical devices.

DOI: 10.1021/jacs.4c03981

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.4c03981