Near-IR-Absorbing BODIPY-5,10-Dihydrophenazine Compact Electron Donor/Acceptor Dyads and Triads: Spin-Orbit Charge Transfer Intersystem Crossing and Charge-Transfer State
Near-IR-Absorbing BODIPY-5,10-Dihydrophenazine Compact Electron Donor/Acceptor Dyads and Triads: Spin-Orbit Charge Transfer Intersystem Crossing and Charge-Transfer State
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DOI：
10.1002/cptc.201900294
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发表时间：
2020-07-01
期刊：
影响因子：
3.7
通讯作者：
Di Donato, Mariangela
中科院分区：
文献类型：
--
作者：
Chen, Kepeng;Taddei, Maria;Di Donato, Mariangela
将 5,10-二氢-5,10-二甲基吩嗪 (PZ) 和硼二吡咯亚甲基 (Bodipy) 连接起来制备紧凑的电子供体/受体二元组和三元组。研究了分子几何形状对紫外-可见吸收、荧光和自旋轨道电荷转移系间窜越（SOCT-ISC）效率的影响。有趣的是，观察到二元组/三元组具有较宽的近红外电荷转移 (CT) 吸收带（中心位于 670 nm），显示出更多的共面几何形状。在具有正交几何形状的三元组中，在低极性溶剂中观察到三重态形成（三重态量子产率为 30%，寿命为 tT= 210 μs）。飞秒瞬态吸收光谱表明快速电荷分离（CS，2 ps）和慢速电荷复合（CR，> 1.5 ns）。通过分子间三重态光敏实验和自旋密度表面分析证实了极性溶剂中二元组/三元组的低位（CT）-C-3态（1.23 eV vs. 1.65，类似于3LE态的1.69 eV）。这些结果对于设计新型宽带、近红外吸收重无原子三重态光敏剂非常有用。
5,10-dihydro-5,10-dimethylphenazine (PZ) and boron dipyrromethene (Bodipy) were linked to prepare compact electron donor/acceptor dyads and triads. The effect of the molecular geometry on the UV-Vis absorption, fluorescence and the spinorbit charge transfer intersystem crossing (SOCT-ISC) efficiency were studied. Interestingly, a broad near-IR charge transfer (CT) absorption band (centred at 670 nm) was observed for the dyad/triad showing more coplanar geometry. Triplet state formation was observed in low polar solvents for the triad with orthogonal geometry (triplet state quantum yield is 30% and lifetime is tT= 210 mu s). Femtosecond transient absorption spectra indicated fast charge separation (CS, 2 ps) and slow charge recombination (CR, > 1.5 ns). The low-lying (CT)-C-3 state of the dyads/triads in polar solvent (1.23 eV vs. the 1.65 similar to 1.69 eV of the 3LE state) was confirmed by intermolecular triplet photosensitizing experiments and the spin density surface analysis. These results are useful for design of new broadband, near-IR absorbing heavy atom-free triplet photosensitizers.