Rigidly linked dinuclear platinum( ii ) complexes showing intense, excimer-like, near-infrared luminescence
Rigidly linked dinuclear platinum( ii ) complexes showing intense, excimer-like, near-infrared luminescence
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刚性连接的双核铂 ( ii ) 配合物显示出强烈的准分子状近红外发光
DOI：
10.1039/d3tc03432a
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发表时间：
2023
影响因子：
6.4
通讯作者：
Pander P
中科院分区：
文献类型：
--
作者：
Pander P
许多发光铂（II）配合物在邻近分子之间进行面对面的相互作用，导致双分子激发态，可能以较低的能量发射（二聚体和/或准分子）。详细的光物理研究报道了双核配合物，其中两个ncn配位Pt（II）单元通过一个杂蒽共价连接，使得分子内形成这种二聚体或准分子态成为可能。这些配合物在低浓度下表现出强烈的准分子样光致发光，而它们的单金属类似物则没有。然而，铂（NCN）单元通过三齿配体（a类）直接与杂蒽相连的配合物（b类）与通过单齿乙酰基配体连接的新一类化合物之间存在显著差异。前者需要大量的几何重排，将Pt（NCN）单元的金属中心移动到足够短的距离，以形成类似准分子的状态。后者只需要很小的变形。因此，a类化合物在固体薄膜中显示出可忽略不计的准分子样发射，因为刚性环境阻碍了必要的几何重排。相比之下，b类配合物在薄膜中显示出强烈的准分子样发射，即使在非常低的负载下也是如此。因此，新的双核分子结构可能为寻求高效的nir发射器件提供新的机会。
Many luminescent platinum(II) complexes undergo face-to-face interactions between neighbouring molecules, leading to bimolecular excited states that may emit at lower energy (dimers and/or excimers). Detailed photophysical studies are reported on dinuclear complexes, in which two NCN-coordinated Pt(II) units are covalently linked by a xanthene such that intramolecular formation of such dimeric or excimeric states is possible. These complexes display strong excimer-like photoluminescence at low concentrations where their monometallic analogues do not. However, a striking difference emerges between complexes where the Pt(NCN) units are directly connected to the xanthene through the tridentate ligand (denoted Class a) and a new class of compounds reported here (Class b) in which the attachment is through a monodentate acetylide ligand. The former require a substantial geometrical rearrangement to move the metal centres of the Pt(NCN) units to a distance short enough to form excimer-like states. The latter require only a small deformation. Consequently, Class a compounds display negligible excimer-like emission in solid films, as the rigid environment hinders the requisite geometric rearrangement. Class b complexes, in contrast, display strong excimer-like emission in film, even at very low loadings. The new dinuclear molecular architecture may thus offer new opportunities in the quest for efficient NIR-emitting devices.