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Long-Lived Triplet Excited State Accessed with Spin-Orbit Charge Transfer Intersystem Crossing in Red Light-Absorbing Phenoxazine-Styryl BODIPY Electron Donor/Acceptor Dyads.
ChemPhysChem ( IF 2.3 ) Pub Date : 2020-06-02 , DOI: 10.1002/cphc.202000300
Yu Dong 1 , Ayhan Elmali 2 , Jianzhang Zhao 1 , Bernhard Dick 3 , Ahmet Karatay 2
Affiliation  

Orthogonal phenoxazine‐styryl BODIPY compact electron donor/acceptor dyads were prepared as heavy atom‐free triplet photosensitizers (PSs) with strong red light absorption (ϵ=1.33×105 M−1 cm−1 at 630 nm), whereas the previously reported triplet photosensitizers based on the spin‐orbit charge transfer intersystem crossing (SOCT‐ISC) mechanism show absorption in a shorter wavelength range (<500 nm). More importantly, a long‐lived triplet state (τT=333 μs) was observed for the new dyads. In comparison, the triplet state lifetime of the same chromophore accessed with the conventional heavy atom effect (HAE) is much shorter (τT=1.8 μs). Long triplet state lifetime is beneficial to enhance electron or energy transfer, the primary photophysical processes in the application of triplet PSs. Our approach is based on SOCT‐ISC, without invoking of the HAE, which may shorten the triplet state lifetime. We used bisstyrylBodipy both as the electron acceptor and the visible light‐harvesting chromophore, which shows red‐light absorption. Femtosecond transient absorption spectra indicated the charge separation (109 ps) and SOCT‐ISC (charge recombination, CR; 2.3 ns) for BDP‐1. ISC efficiency of BDP‐1 was determined as ΦT=25 % (in toluene). The dyad BDP‐3 was used as triplet PS for triplet‐triplet annihilation upconversion (upconversion quantum yield ΦUC=1.5 %; anti‐Stokes shift is 5900 cm−1).

中文翻译:

通过红光吸收吩恶嗪-苯乙烯基 BODIPY 电子供体/受体二元体中的自旋轨道电荷转移系间窜越获得长寿命的三重态激发态。

正交吩恶嗪-苯乙烯基BODIPY紧凑电子供体/受体二元体被制备为具有强红光吸收( 630 nm处ε = 1.33×10 5  M -1  cm -1)的无重原子三线态光敏剂(PSs),而之前报道的基于自旋轨道电荷转移系间窜越(SOCT-ISC)机制的三重态光敏剂在较短波长范围(<500 nm)内显示出吸收。更重要的是,在新的二元体中观察到了长寿命的三重态(τ T = 333 μs)。相比之下,通过传统重原子效应(HAE)获得的相同发色团的三重态寿命要短得多(τ T =1.8 μs)。长的三重态寿命有利于增强电子或能量转移,这是三重态PS应用中的主要光物理过程。我们的方法基于 SOCT-ISC,不调用 HAE,这可能会缩短三线态寿命。我们使用双苯乙烯基Bodipy作为电子受体和可见光捕获发色团,其显示出红光吸收。飞秒瞬态吸收光谱表明BDP-1的电荷分离(109 ps)和 SOCT-ISC(电荷复合,CR;2.3 ns) 。BDP-1的 ISC 效率确定为 Φ T =25 %(在甲苯中)。二重态BDP-3用作三重态PS进行三重态-三重态湮没上转换(上转换量子产率Φ UC =1.5%;反斯托克斯位移为5900 cm -1)。
更新日期:2020-06-02
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