Highly Efficient Phosphorescent Tetradentate Platinum(II) Complexes Containing Fused 6/5/6 Metallocycles
Highly Efficient Phosphorescent Tetradentate Platinum(II) Complexes Containing Fused 6/5/6 Metallocycles
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含有稠合 6/5/6 金属环的高效磷光四齿铂 (II) 配合物
DOI：
10.1021/acs.inorgchem.9b03376
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发表时间：
2020-03-16
影响因子：
4.6
通讯作者：
She, Yuanbin
中科院分区：
文献类型：
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作者：
Li, Guijie;Zhan, Feng;She, Yuanbin
设计并合成了一系列具有6/5/6稠合双环和含联苯（bp）配体的中性四齿Pt（II）配合物。所有的桥连原子都采用氮原子，设计为吖啶基（Ac）、氮杂吖啶基（AAc）和氮杂咔唑基（ACz），这可以有效地调节它们的LUMO能级。它们的HOMO能级可以很好地控制，通过分子修饰的bp部分与供电子和吸电子基团。这些分子修饰也对Pt（II）配合物的电化学和光物理性质和光稳定性具有深远的影响。用密度泛函理论（DFT）、含时密度泛函理论（TD-DFT）和自然跃迁轨道（NTO）方法对基态和激发态进行了系统的研究。所有的Pt（II）配合物在不同比例的T-1态下都表现出混合（3）（LC/MLCT）特征，并且具有很强的结构依赖性。这些6/5/6 Pt（II）配合物在室温下在二氯甲烷溶液（Phi（PL）= 27-51%）和掺杂的PMMA膜（Phi（PL）= 36-52%）中表现出高的量子效率，分别具有1.6-9.5 μ s和7.6-9.0 μ s的短发光寿命。它们在溶液中发射绿色光，主峰分别为512-529 nm，在掺杂的PMMA膜中发射绿光，主峰分别为512-524 nm。重要的是，Pt（bp-2）在各种基质中表现出高度稳定的发射颜色，在512 nm处具有相同的主峰，并且还表现出较长的光稳定性寿命，LT 80，在初始亮度的80%下为190 min，其掺杂在聚苯乙烯膜（5 wt %）中，由375 nm的UV光以500 W/m（2）激发。这些研究表明，这些6/5/6 Pt（II）配合物可以作为良好的磷光发光体的OLED应用，并应提供一个可行的路线，开发高效和稳定的Pt（II）基磷光发光体。
A series of neutral tetradentate Pt(II) complexes with fused 6/5/6 metallocycles and biphenyl (bp)-containing ligands have been designed and synthesized. All bridging atoms adopt nitrogens designed as an acridinyl group (Ac), an aza acridinyl group (AAc), and an aza carbazolyl group (ACz), which can effectively tune their LUMO energy levels. Their HOMO energy levels can be well-controlled through molecular modifications on the bp moieties with electron-donating and electron-withdrawing groups. These molecular modifications also have profound effects on the electrochemical and photophysical properties and photostabilities of the Pt(II) complexes. The ground-states and excited states are systematically studied by density functional theory (DFT), time-dependent density functional theory (TD-DFT), and natural transition orbital (NTO) calculations. All the Pt(II) complexes exhibit admixed (3)(LC/MLCT) characters in T-1 states with various proportions, which are strongly structure-dependent. These 6/5/6 Pt(II) complexes demonstrate high quantum efficiencies in dichloromethane solutions (Phi(PL) = 27-51%) and in doped PMMA films (Phi(PL) = 36-52%) at room temperature with short luminescence lifetimes of 1.6-9.5 mu s and 7.6-9.0 mu s, respectively. They emit green light with dominant peaks of 512-529 nm in solutions and 512-524 nm in doped PMMA films, respectively. Importantly, Pt(bp-2) exhibits highly stable emission colors with the same dominant peaks at 512 nm in various matrixes and also demonstrates a long photostability lifetime, LT80, at 80% of initial luminance, of 190 min, which is doped in polystyrene films (5 wt %) excited by UV light of 375 nm at 500 W/m(2). These studies indicate that these 6/5/6 Pt(II) complexes can act as good phosphorescent emitters for OLED applications and should provide a viable route for the development of efficient and stable Pt(II)-based phosphorescent emitters.