Phosphorescent mesomorphic dyads based on tetraacetylethane complexes of iridium(III).
Phosphorescent mesomorphic dyads based on tetraacetylethane complexes of iridium(III).
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DOI：
10.1002/anie.201105212
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发表时间：
2012-01
影响因子：
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通讯作者：
A. Prokhorov;Amedeo Santoro;J. Williams;D. Bruce
中科院分区：
文献类型：
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作者：
A. Prokhorov;Amedeo Santoro;J. Williams;D. Bruce
由于Ir和铂与芳香族配体的配合物具有高的自旋-轨道耦合常数，可以促进三重态的磷光，这一过程在其他方面是被正式禁止的，因此作为发光材料是有兴趣的。它们与有机发光二极管(OLED)技术特别相关，在OLED技术中，电荷的组合导致了三重态到单重态的过剩，尽管它们在生物成像和传感等领域的应用最近也受到了极大的关注。掺入发光络合物可以通过促进三重态发射，将OLED的最大内效率提高到100%。4]Thompson和他的同事已经证明了双(2-苯基吡啶)Ir(III)发色团是一种非常有效的三重态发光体，其物理性质使其适合于集成到器件中，并且其发射特性可以很容易地通过取代配体来调节。将液晶性的性质添加到发射材料中也是很有意义的，因为不同中间相中分子的有序状态表明了电荷载流子传输的改进途径，而某些中间相提供了极化发射的可能性。我们已经报道了基于1，3-二(2-吡啶)苯配体形成柱状相的液晶铂(II)化合物，而基于扩展的2，5-二苯基吡啶的液晶铂(II)化合物显示出向列相和SMA相，具有非常高的光致发光量子产率。最近，在报道了Ir(III)的发光离子液晶配合物之后，我们报道了第一个基于六烯基苯基吡啶(PPy)配体的Ir(III)的电荷中性发光介晶配合物的例子，并以乙酰丙酮(Acac)为辅助配体(1a)。在同一项研究中，基于四碳烯酸配体的相关络合物(1b)被发现是高度发射的(F=50%)，但不是液晶性的，而同一配体的二-间氯二聚体2是液晶性的，但几乎不发光(F<；1%；图1)。
Complexes of iridium and platinum with aromatic ligands are of interest as emissive materials owing to their high spin–orbit coupling constants, which can promote phosphorescence from triplet states, a process that is otherwise formally forbidden. They are particularly relevant to organic light-emitting diode (OLED) technology, where the combination of charges leads to a surplus of triplet to singlet states, although their application in areas such as bioimaging and sensing have also received recent significant attention. Incorporation of emissive complexes can raise the maximum internal efficiency of an OLED to 100% by promoting triplet emission. 4] Thompson and co-workers have shown that the bis(2phenylpyridine)iridium(III) chromophore is a very effective triplet emitter, the physical properties of which make it suitable for incorporation into devices, and the emission characteristics of which can be readily tuned through substitution of the ligands. To add the property of liquid crystallinity to emissive materials is also of interest, for the ordered state of the molecules in the different mesophases suggests an improved pathway for the transport of charge carriers, whereas certain mesophases offer the possibility of polarized emission. We have reported liquid-crystalline Pt(II) phosphor compounds based on 1,3-di(2-pyridyl)benzene ligands that form columnar phases, whereas those based on extended 2,5-diphenylpyridines show nematic and SmA phases with very high photoluminescent quantum yields. More recently and following a report of a luminescent, ionic, liquid-crystalline complex of Ir(III), we reported the first example of a charge-neutral, luminescent, mesogenic complex of Ir(III) based on a hexacatenar phenylpyridine (ppy) ligand, with acetylacetonate (acac) as an ancillary ligand (1a). In the same study, a related complex (1b) based on a tetracatenar ligand was found to be highly emissive (F = 50%) but not liquid-crystalline, whereas the di-m-chloro dimer, 2, of the same ligand was liquid-crystalline, but scarcely emissive (F< 1%; Figure 1).