Hou Yuqi, Liu Jinling, Zhang Nan, Zhao Jianzhang
State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, E-208 West Campus, 2 Ling Gong Road, Dalian 116024, P.R. China.
J Phys Chem A. 2020 Nov 12;124(45):9360-9374. doi: 10.1021/acs.jpca.0c07907. Epub 2020 Nov 3.
The spin-orbit charge transfer intersystem crossing (SOCT-ISC) and the formation of a long-lived charge transfer (CT) state were studied with a series of 4,4'-dimethoxy triphenylamine-BODIPY compact electron donor/acceptor dyads. Different torsion freedoms were applied in the dyads to tune the electronic coupling between the donor and acceptor, and a red-shifted CT absorption band was observed for one dyad. The dyads show solvent polarity-dependent singlet oxygen photosensitizing ability (quantum yields 3%-79%). Nanosecond transient absorption spectra of the dyad in nonpolar solvent confirm the formation of triplet states. The intrinsic triplet state lifetime is up to 383 μs (in fluid solution), which is much longer than that accessed with the heavy atom effect (276 μs). Intermolecular triplet photosensitizing of the dyads in a polar solvent produces a long-lived CT state (lifetime, τ = 8.0 μs supported by the electron spin density surface analysis). The triplet state lifetime of the dyads doped in a Clear Flex 50 polymer film is exceptionally long (7.6-11.4 ms), and formation of a long-lived CT state (37 μs) was observed. Triplet-triplet annihilation upconversion was performed with the electron donor/acceptor dyads used as the triplet photosensitizer and perylene used as the triplet acceptor; the upconversion quantum yield is up to 15.8%.
利用一系列4,4'-二甲氧基三苯胺-硼二吡咯紧凑电子供体/受体二元体系，研究了自旋轨道电荷转移系间窜越（SOCT-ISC）和长寿命电荷转移（CT）态的形成。在二元体系中应用了不同的扭转自由度来调节供体和受体之间的电子耦合，并且观察到一个二元体系的CT吸收带发生了红移。这些二元体系表现出溶剂极性依赖性单线态氧光敏化能力（量子产率为3%-79%）。在非极性溶剂中该二元体系的纳秒瞬态吸收光谱证实了三重态的形成。其固有三重态寿命长达383 μs（在流体溶液中），这比通过重原子效应获得的寿命（276 μs）长得多。在极性溶剂中该二元体系的分子间三重态光敏化产生了一个长寿命的CT态（寿命，τ = 8.0 μs，电子自旋密度表面分析证实）。掺杂在Clear Flex 50聚合物薄膜中的二元体系的三重态寿命异常长（7.6-11.4 ms），并且观察到形成了一个长寿命的CT态（37 μs）。以电子供体/受体二元体系作为三重态光敏剂、苝作为三重态受体进行了三重态-三重态湮灭上转换；上转换量子产率高达15.8%。
