State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, PR China.
Chemistry. 2012 Feb 13;18(7):1961-8. doi: 10.1002/chem.201102634. Epub 2012 Jan 16.
Room-temperature long-lived near-IR phosphorescence of boron-dipyrromethene (BODIPY) was observed (λ(em) = 770 nm, Φ(P) = 3.5 %, τ(P) = 128.4 μs). Our molecular-design strategy is to attach Pt(II) coordination centers directly onto the BODIPY π-core using acetylide bonds, rather than on the periphery of the BODIPY core, thus maximizing the heavy-atom effect of Pt(II). In this case, the intersystem crossing (ISC) is facilitated and the radiative decay of the T(1) excited state of BODIPY is observed, that is, the phosphorescence of BODIPY. The complex shows strong absorption in the visible range (ε = 53,800 M(-1) cm(-1) at 574 nm), which is rare for Pt(II)-acetylide complexes. The complex is dual emissive with (3)MLCT emission at 660 nm and the (3)IL emission at 770 nm. The T(1) excited state of the complex is mainly localized on the BODIPY moiety (i.e. (3)IL state, as determined by steady-state and time-resolved spectroscopy, 77 K emission spectra, and spin-density analysis). The strong visible-light-harvesting ability and long-lived T(1) excite state of the complex were used for triplet-triplet annihilation based upconversion and an upconversion quantum yield of 5.2 % was observed. The overall upconversion capability (η = ε×Φ(UC)) of this complex is remarkable considering its strong absorption. The model complex, without the BODIPY moiety, gives no upconversion under the same experimental conditions. Our work paves the way for access to transition-metal complexes that show strong absorption of visible light and long-lived (3)IL excited states, which are important for applications in photovoltaics, photocatalysis, and upconversions, etc.
室温下观察到硼二吡咯甲川（BODIPY）的长寿命近红外磷光（λ（em）= 770nm，Φ（P）= 3.5％，τ（P）= 128.4μs）。我们的分子设计策略是使用炔键将 Pt（II）配位中心直接连接到 BODIPY π-核上，而不是连接到 BODIPY 核的外围，从而最大限度地提高 Pt（II）的重原子效应。在这种情况下，促进了系间窜越（ISC），并观察到 BODIPY 的 T（1）激发态的辐射衰减，即 BODIPY 的磷光。该配合物在可见光范围内具有很强的吸收（在 574nm 处ε=53800M（-1）cm（-1）），这对于 Pt（II）-炔配合物来说很少见。该配合物具有双重发射性，在 660nm 处具有（3）MLCT 发射，在 770nm 处具有（3）IL 发射。该配合物的 T（1）激发态主要定域在 BODIPY 部分（即（3）IL 态，通过稳态和时间分辨光谱、77K 发射光谱和自旋密度分析确定）。配合物的强可见光收集能力和长寿命 T（1）激发态用于三重态-三重态湮灭上转换，并观察到 5.2％的上转换量子产率。考虑到其强吸收，该配合物的整体上转换能力（η=ε×Φ（UC））非常显著。在相同的实验条件下，没有 BODIPY 部分的模型配合物没有发生上转换。我们的工作为获得具有强可见光吸收和长寿命（3）IL 激发态的过渡金属配合物铺平了道路，这对于在光伏、光催化和上转换等方面的应用非常重要。
