金属铱配合物中萘酰亚胺的长寿命室温深红光内配体三重态激发态及其在三重态-三重态湮灭上转换中的应用。
Long-lived room-temperature deep-red-emissive intraligand triplet excited state of naphthalimide in cyclometalated Ir(III) complexes and its application in triplet-triplet annihilation-based upconversion.
机构信息
State Key Laboratory of Fine Chemicals, E-208, West Compus, Dalian University of Technology, Dalian 116024, China.
出版信息
Chemistry. 2012 Jun 25;18(26):8100-12. doi: 10.1002/chem.201200224. Epub 2012 May 21.
Cyclometalated Ir(III) complexes with acetylide ppy and bpy ligands were prepared (ppy = 2-phenylpyridine, bpy = 2,2'-bipyridine) in which naphthal (Ir-2) and naphthalimide (NI) were attached onto the ppy (Ir-3) and bpy ligands (Ir-4) through acetylide bonds. [Ir(ppy)(3)] (Ir-1) was also prepared as a model complex. Room-temperature phosphorescence was observed for the complexes; both neutral and cationic complexes Ir-3 and Ir-4 showed strong absorption in the visible range (ε=39,600 M(-1) cm(-1) at 402 nm and ε=25,100 M(-1) cm(-1) at 404 nm, respectively), long-lived triplet excited states (τ(T)=9.30 μs and 16.45 μs) and room-temperature red emission (λ(em)=640 nm, Φ(p)=1.4 % and λ(em)=627 nm, Φ(p)=0.3 %; cf. Ir-1: ε=16,600 M(-1) cm(-1) at 382 nm, τ(em)=1.16 μs, Φ(p)=72.6 %). Ir-3 was strongly phosphorescent in non-polar solvent (i.e., toluene), but the emission was completely quenched in polar solvents (MeCN). Ir-4 gave an opposite response to the solvent polarity, that is, stronger phosphorescence in polar solvents than in non-polar solvents. Emission of Ir-1 and Ir-2 was not solvent-polarity-dependent. The T(1) excited states of Ir-2, Ir-3, and Ir-4 were identified as mainly intraligand triplet excited states ((3)IL) by their small thermally induced Stokes shifts (ΔE(s)), nanosecond time-resolved transient difference absorption spectroscopy, and spin-density analysis. The complexes were used as triplet photosensitizers for triplet-triplet annihilation (TTA) upconversion and quantum yields of 7.1 % and 14.4 % were observed for Ir-2 and Ir-3, respectively, whereas the upconversion was negligible for Ir-1 and Ir-4. These results will be useful for designing visible-light-harvesting transition-metal complexes and for their applications as triplet photosensitizers for photocatalysis, photovoltaics, TTA upconversion, etc.
合成了具有炔键连接的二吡啶并[3,2-a:2',3'-c]吩嗪（ppy）和 2,2'-联吡啶（bpy）配体的环金属化 Ir(III) 配合物（ppy = 2-苯基吡啶，bpy = 2,2'-联吡啶），其中萘（Ir-2）和萘酰亚胺（NI）通过炔键连接到 ppy（Ir-3）和 bpy 配体（Ir-4）上。[Ir(ppy)(3)]（Ir-1）也被制备为模型配合物。该配合物在室温下表现出磷光；中性和阳离子配合物 Ir-3 和 Ir-4 在可见光范围内具有强吸收（在 402nm 处 ε=39600 M(-1) cm(-1)，在 404nm 处 ε=25100 M(-1) cm(-1)），长寿命三重态激发态（τ(T)=9.30 μs 和 16.45 μs）和室温红色发射（λ(em)=640nm，Φ(p)=1.4 %和 λ(em)=627nm，Φ(p)=0.3 %；与 Ir-1 相比：在 382nm 处 ε=16600 M(-1) cm(-1)，τ(em)=1.16 μs，Φ(p)=72.6 %）。Ir-3 在非极性溶剂（即甲苯）中具有强烈的磷光，但在极性溶剂中发射完全猝灭。Ir-4 对溶剂极性表现出相反的响应，即在极性溶剂中比在非极性溶剂中具有更强的磷光。Ir-1 和 Ir-2 的发射不受溶剂极性的影响。Ir-2、Ir-3 和 Ir-4 的 T(1)激发态通过较小的热诱导斯托克斯位移（ΔE(s)）、纳秒时间分辨瞬态差分吸收光谱和自旋密度分析确定为主要的内配体三重态激发态（(3)IL）。这些配合物被用作三重态光敏剂用于三重态-三重态湮灭（TTA）上转换，观察到 Ir-2 和 Ir-3 的量子产率分别为 7.1%和 14.4%，而 Ir-1 和 Ir-4 的上转换可以忽略不计。这些结果将有助于设计可见光收集过渡金属配合物，并将其用作光催化、光伏、TTA 上转换等的三重态光敏剂。
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