Platinum(ii) complexes with cyclometallated 5-π-delocalized-donor-1,3-di(2-pyridyl)benzene ligands as efficient phosphors for NIR-OLEDs
作者:Filippo Nisic、Alessia Colombo、Claudia Dragonetti、Dominique Roberto、Adriana Valore、Joanna M. Malicka、Massimo Cocchi、Gemma R. Freeman、J. A. Gareth Williams
DOI:10.1039/c3tc32086c
日期:——
Two new pincer proligands, namely 5-(p-(N,N-diphenylamino)phenylethynyl)-1,3-di(2-pyridyl)benzene (HL1) and trans-5-(p-(N,N-diphenylamino)styryl-1,3-di(2-pyridyl)benzene (HL2) were prepared together with their N^C^N-coordinated cyclometallated platinum(II) complexes PtL1X (X = Cl, NCS) and PtL2Cl. Both ligands are intensely luminescent in solution (quantum yields > 0.8). PtL1X complexes display high quantum yields in solution whereas that of PtL2Cl is very low due to the ease with which trans to cis isomerisation of the diphenylaminostyryl CC bond occurs. Distinct sets of emission bands attributable to the cis and trans forms are observable in glass at 77 K, the assignments being supported by TD-DFT calculations. Organic light-emitting diodes (OLEDs) have been prepared using the new compounds as phosphorescent emitters. Remarkably, despite the inferior quantum yield of PtL2Cl in solution, the best electroluminescence quantum efficiencies are obtained with this complex, which emerges as an excellent candidate for the preparation of NIR-OLEDs.
研究人员制备了两种新型钳状原配体,即 5-(对-(N,N-二苯基氨基)苯乙炔基)-1,3-二(2-吡啶基)苯 (HL1) 和反式-5-(对-(N,N-二苯基氨基)苯乙烯基)-1,3-二(2-吡啶基)苯 (HL2),以及它们的 N^C^N 配位环金属化铂(II)配合物 PtL1X (X = Cl, NCS) 和 PtL2Cl。这两种配体在溶液中都能强烈发光(量子产率大于 0.8)。PtL1X 复合物在溶液中的量子产率很高,而 PtL2Cl 的量子产率则很低,这是因为二苯胺苯乙烯 CC 键很容易发生反式到顺式的异构化。在 77 K 的玻璃中可以观察到顺式和反式的不同发射带,TD-DFT 计算支持了这些分配。利用这些新化合物作为磷光发光体,制备了有机发光二极管(OLED)。值得注意的是,尽管 PtL2Cl 在溶液中的量子产率较低,但这种复合物却能获得最佳的电致发光量子效率,成为制备近红外有机发光二极管的最佳候选化合物。