中山大学潘梅团队报道了ESIPT属性配位聚合物的热激活荧光与长持续发光。相关研究成果发表在2022年1月9日出版的《美国化学会杂志》。

激发态分子内质子转移（ESIPT）分子表现出特殊的烯醇-酮互变异构和相关的光致发光（PL）开关，在显示、传感、成像、激光等方面有着广泛的应用，ESIPT属性的配位聚合物在热激活荧光（TAF）和长持续发光（LPL）之间表现出交替的PL，这一点从未被探索过。

该文中，研究人员报告了由ESIT型配体HPI2C（5-（2-（2-羟基苯基）-4,5-二苯基-1H-咪唑-1-基）间苯二甲酸）组装的动态Cd（II）配位聚合物（LIFM-101）。首次在ESIPT激发态的指导下通过控制温度实现了TAF和/或颜色调谐LPL。值得注意的是，LIFM-101中HPI2C配体的扭曲结构实现了高能激发态的有效混合，导致高位酮三重态（Tn（K*））和第一单重态（S1（K*）之间的ISC（系统间交叉）/RISC（反向系统间交叉）能量转移。

同时，实验和理论结果表明RISC、ISC和内转换（IC）在这种独特的ESIPT属性配位聚合物中的发生概率和相关性，导致了前所未有的TAF/LPL开关机制，并为未来先进光学材料的设计和应用铺平了道路。

附：英文原文

Title: Thermally Activated Fluorescence vs Long Persistent Luminescence in ESIPT-Attributed Coordination Polymer

Author: Peng-Yan Fu, Bao-Ning Li, Qiang-Sheng Zhang, Jun-Ting Mo, Shi-Cheng Wang, Mei Pan, Cheng-Yong Su

Issue&Volume: January 9, 2022

Abstract: Excited-state intramolecular proton transfer (ESIPT) molecules demonstrating specific enol-keto tautomerism and the related photoluminescence (PL) switch have wide applications in displaying, sensing, imaging, lasing, etc. However, an ESIPT-attributed coordination polymer showing alternative PL between thermally activated fluorescence (TAF) and long persistent luminescence (LPL) has never been explored. Herein, we report the assembly of a dynamic Cd(II) coordination polymer (LIFM-101) from the ESIPT-type ligand, HPI2C (5-(2-(2-hydroxyphenyl)-4,5-diphenyl-1H-imidazol-1-yl)isophthalic acid). For the first time, TAF and/or color-tuned LPL can be achieved by controlling the temperature under the guidance of ESIPT excited states. Noteworthily, the twisted structure of the HPI2C ligand in LIFM-101 achieves an effective mixture of the higher-energy excited states, leading to ISC (intersystem crossing)/RISC (reverse intersystem crossing) energy transfer between the high-lying keto-triplet state (Tn(K*)) and the first singlet state (S1(K*)). Meanwhile, experimental and theoretical results manifest the occurrence probability and relevance among RISC, ISC, and internal conversion (IC) in this unique ESIPT-attributed coordination polymer, leading to the unprecedented TAF/LPL switching mechanism, and paving the way for the future design and application of advanced optical materials.

DOI: 10.1021/jacs.1c11874

Source: https://pubs.acs.org/doi/10.1021/jacs.1c11874