State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, E-208 West Campus, 2 Ling-Gong Road, Dalian 116024, PR China.
Dalton Trans. 2013 Feb 14;42(6):2062-74. doi: 10.1039/c2dt32420b.
We prepared N^N Re(I) tricarbonyl chloride complexes (Re-1 and Re-2) that give very strong absorption of visible light. To this end, it is for the first time that boron dipyrimethane (Bodipy) was used to prepare Re(I) tricarbonyl chloride complexes. The π-conjugation linker between the π-conjugation framework of the antenna Bodipy and the Re(I) coordination centre ensures efficient intersystem crossing (ISC). Re-0 without visible light-harvesting ligand was prepared as a model complex in the photophysical studies. Re-1 (with Bodipy) and Re-2 (with carbazole-ethynyl Bodipy) show unprecedented strong absorption of visible light at 536 nm (ε = 91700 M(−1) cm(−1)) and 574 nm (ε = 64,600 M(−1) cm(−1)), respectively. Interestingly, different from Re-0, Re-1 and Re-2 show fluorescence of the ligand, not the phosphorescence of the Re(I) coordination centre. However, long-lived triplet excited states were observed upon visible light excitation (τ(T) = 104.0 μs for Re-1; τ(T) = 127.2 μs for Re-2) vs. the short lifetime of Re-0 (τ(T) = 26 ns). With nanosecond time-resolved transient absorption spectroscopy and DFT calculations, we proved that the triplet excited states of Re-1 and Re-2 are localized on the Bodipy ligands. The complexes were used as triplet photosensitizers for two triplet–triplet-energy-transfer (TTET) processes, i.e.(1)O(2) mediated photooxidation and triplet–triplet annihilation (TTA) upconversion. With the strong visible light-harvesting ability, Re-1 proved to be a better (1)O(2) photosensitizer than the conventional triplet photosensitizer tetraphenylporphyrin (TPP). Significant upconversion was observed with Re-1 as the triplet photosensitizer. Our result is useful for preparation of Re(I) tricarbonyl chloride complexes that show strong absorption of visible light and long-lived triplet excited states and for the application of these complexes as triplet photosensitizers in photocatalysis, photodynamic therapy and TTA upconversion.
我们制备了 N^N Re(I) 三羰基氯化物配合物（Re-1 和 Re-2），它们对可见光具有很强的吸收。为此，首次使用硼二吡咯甲烷（Bodipy）制备了 Re(I) 三羰基氯化物配合物。天线 Bodipy 的 π-共轭骨架与 Re(I) 配位中心之间的π-共轭连接体确保了有效的系间窜越（ISC）。在光物理研究中，制备了没有可见光收集配体的 Re-0 作为模型配合物。Re-1（带有 Bodipy）和 Re-2（带有咔唑-乙炔基 Bodipy）在 536nm（ε=91700M(-1)cm(-1)）和 574nm（ε=64600M(-1)cm(-1)）处表现出前所未有的可见光强吸收。有趣的是，与 Re-0 不同，Re-1 和 Re-2 显示配体的荧光，而不是 Re(I) 配位中心的磷光。然而，在可见光激发下观察到长寿命三重态激发态（Re-1 的 τ(T)=104.0μs；Re-2 的 τ(T)=127.2μs），而 Re-0 的寿命较短（τ(T)=26ns）。通过纳秒时间分辨瞬态吸收光谱和 DFT 计算，我们证明了 Re-1 和 Re-2 的三重态激发态定域在 Bodipy 配体上。该配合物被用作两种三重态-三重态能量转移（TTET）过程的三重态光敏剂，即（1）O(2)介导的光氧化和三重态-三重态湮灭（TTA）上转换。由于具有很强的可见光吸收能力，Re-1 被证明是比传统三重态光敏剂四苯基卟啉（TPP）更好的（1）O(2)光敏剂。使用 Re-1 作为三重态光敏剂时，观察到明显的上转换。我们的结果可用于制备对可见光具有强吸收和长寿命三重态激发态的 Re(I) 三羰基氯化物配合物，并将这些配合物作为三重态光敏剂应用于光催化、光动力治疗和 TTA 上转换中。
