Wang Xuanhang, Song Yucong, Pan Guocui, Han Wenkun, Wang Boyu, Cui Li, Ma Huili, An Zhongfu, Xie Zhigang, Xu Bin, Tian Wenjing
State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University Qianjin Street No. 2699 Changchun 130012 China
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences Changchun 130022 PR China
Chem Sci. 2020 Sep 2;11(40):10921-10927. doi: 10.1039/d0sc03128c.
Fluorescent photosensitizers (PSs) often encounter low singlet oxygen (O) quantum yields and fluorescence quenching in the aggregated state, mainly involving the intersystem crossing process. Herein, we successfully realize maximizing O quantum yields of fluorescent PSs through promoting radical-pair intersystem crossing (RP-ISC), which serves as a molecular symmetry-controlling strategy of donor-acceptor (D-A) motifs. The symmetric quadrupolar A-D-A molecule PTP exhibits an excellent O quantum yield of 97.0% with bright near-infrared fluorescence in the aggregated state. Theoretical and ultrafast spectroscopic studies suggested that the RP-ISC mechanism dominated the formation of the triplet for PTP, where effective charge separation and an ultralow singlet-triplet energy gap (0.01 eV) enhanced the ISC process to maximize O generation. Furthermore, and experiments demonstrated the dual function of PTP as a fluorescent imaging agent and an anti-cancer therapeutic, with promising potential applications in both diagnosis and theranostics.
荧光光敏剂（PSs）在聚集态时常常面临单线态氧（O）量子产率低和荧光猝灭的问题，这主要涉及系间窜越过程。在此，我们通过促进自由基对系间窜越（RP-ISC）成功实现了荧光PSs的单线态氧量子产率最大化，这是一种供体-受体（D-A）基序的分子对称性控制策略。对称四极A-D-A分子PTP在聚集态下表现出97.0%的优异单线态氧量子产率以及明亮的近红外荧光。理论和超快光谱研究表明，RP-ISC机制主导了PTP三线态的形成，其中有效的电荷分离和超低的单线态-三线态能隙（0.01 eV）增强了ISC过程，从而使单线态氧的产生最大化。此外，实验证明了PTP作为荧光成像剂和抗癌治疗剂的双重功能，在诊断和治疗诊断学方面具有广阔的潜在应用前景。
