Orthogonal carbazole-perylene bisimide pentad:a photoconversion-tunable photosensitizer with diversified excitation and excited-state relaxation pathways

• 作者: Zhaolong Wang Yue Sun Simin Lin Gang Wang Xingmao Chang Xinyu Gou Taihong Liu Shengye Jin Gang He Yu-Chen Wei Pi-Tai Chou Yu Fang
• 来源期刊: 中国科学：化学（英文版）
• 年，卷（期）: 2021,（12）
• 所属期刊栏目: ARTICLES
• 页码范围: 2193-2202
• 页数: 10页
• 语种: 英文

摘要

Integrating multiple photosensitive properties into an "all-in-one" photosensitizer (PS) shows great promise for the treatment of cancers owing to synergistic effect among them.However,the development of such PSs,especially those that need a single laser source,remains a challenge.Herein,we report an orchestration of electron donors and acceptors in a propeller-like pentad,PBI-4Cz,where four carbazole (Cz) units are covalently linked to the ortho-positions of the perylene bisimide (PBI) core.Strong intramolecular donor-acceptor interaction significantly quenches the luminescence and largely extends the absorption spectra to near-infrared region.Excited-state dynamics investigated via femto-and nano-second transient absorption spectroscopy revealed exclusive charge separation of the PBI-4Cz within initial 0.5 ps when photoexcited regardless of which intermediate is involved.Energy dissipation of the resulting charge-separated state (PBI·--4Cz·+) is subjected to the toggle between intersystem-crossing toward excited triplet states and charge recombination toward ground states.Relative importance of the two pathways can be tuned by micro-environmental polarity,which endows PBI-4Cz remarkable performances of singlet-oxygen generation(＞90.0％) in toluene and photothermal conversion (～28.6％) in DMSO.Harnessing intrinsic photostability and excited-state processes of heavy-atom-free PBI derivatives not only holds a promise for multifunctional phototheranostics,but also provides a prototype for designing high-performance PSs with tunable photoconversion pathways.