In this work, six Pt(II) complexes based on 4,4′-bis(triethylsilylethynyl)-2,2′-bipyridine ligand were designed and synthesized. The crystal structures of complexes 1, 2, 5 and 6 showed that these complexes adopt dimer structures with ultra-short intermolecular Pt⋯Pt distances [3.1674(4)–3.1973(7) Å]. In the solid state, all complexes exhibited long-wavelength NIR luminescence with maximum emission centered at 1045 nm for 1, 1062 nm for 2, 939 nm for 3, 1051 nm for 4, 1037 nm for 5, and 1029 nm for 6. This is the first report on the Pt(II) dimer with luminescence exceeding 1000 nm. More importantly, 1062 nm of complex 2 is the longest emission wavelength of the reported 2,2′-bipyridyl-platinum(II) complex. Furthermore, these complexes also exhibited reversible mechanoluminescence property. Systematic studies on the crystal structure, photophysical properties and PXRD patterns revealed that the long-wavelength NIR luminescence of dimers is due to the enhanced MMLCT transitions, and the mechanism of reversible mechanoluminescence property involves changes in the strength of the Pt–Pt interaction caused by reversible alteration of intermolecular Pt⋯Pt distances during the mechanical grinding-vapor absorbing process.

中文翻译：

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通过增强的 Pt-Pt 相互作用实现 2,2'-联吡啶-Pt(II) 二聚体的长波长 NIR 发光

在这项工作中，设计并合成了六种基于 4,4'-双(三乙基甲硅烷基乙炔基)-2,2'-联吡啶配体的Pt( II ) 配合物。复合物的晶体结构1，2，5和6表明，这些配合物通过与超短分子间的Pt的Pt⋯距离[3.1674（4）-3.1973（7）]二聚体结构。在固体状态下，所有的复合物表现出长波长发光NIR与最大发射中心在对1045纳米1，为1062纳米2，对于939纳米的3，为1051纳米4，为1037纳米5，以及用于1029纳米6。这是关于 Pt( II ) 的第一份报告) 发光超过 1000 nm 的二聚体。更重要的是，1062 nm 的配合物2是所报道的 2,2'-联吡啶-铂 ( II ) 配合物的最长发射波长。此外，这些配合物还表现出可逆的机械发光特性。对晶体结构、光物理性质和 PXRD 图案的系统研究表明，二聚体的长波长 NIR 发光是由于增强的 MMLCT 跃迁，可逆机械发光性质的机制涉及 Pt-Pt 相互作用强度的变化。在机械研磨蒸汽吸收过程中分子间 Pt⋯Pt 距离的可逆变化。