Baranova Kristina F, Titov Aleksei A, Shakirova Julia R, Baigildin Vadim A, Smol'yakov Alexander F, Valyaev Dmitry A, Ning Guo-Hong, Filippov Oleg A, Tunik Sergey P, Shubina Elena S
A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov Str., 28, 119991 Moscow, Russia.
Institute of Chemistry, St. Petersburg State University, Universitetskii pr., 26, 198504 St. Petersburg, Russia.
Inorg Chem. 2024 Sep 9;63(36):16610-16621. doi: 10.1021/acs.inorgchem.4c00751. Epub 2024 Aug 28.
A series of structurally similar trinuclear macrocyclic copper(I) and silver(I) pyrazolate complexes bearing various short-bite diphosphine RPCH(R')PR ligands are reported. Upon diphosphine coordination, the planar geometry of the initial complexes undergoes bending along the line between two metal atoms coordinated to the phosphorus moieties. The complexes based on dcpm ligands (R = cyclohexyl, R' = H, Ph) do not exhibit dynamic behavior in solution at room temperature on the P NMR time scale as it was previously observed for similar trinuclear copper complexes bearing the dppm (R = Ph, R' = H) scaffold. All copper(I) complexes exhibit thermally activated delayed fluorescence (TADF) behavior in the solid state. Importantly, the use of aliphatic substituents on the phosphorus atoms instead of aromatic ones leads to an almost double increase in the quantum efficiency (Φ) of photoluminescence by eliminating nonradiative decay from the LC states of the dppm aromatic rings. The higher donating ability of the substituents in the pyrazolate ligand (CF vs CH) lowers the energy of the metal-centered excited state, allowing for a significant metal impact on the T state. Finally, the Ag(I) complex displays an emission efficiency of approximately 14%, being the highest among known trinuclear silver(I) pyrazolate homometallic derivatives.
报道了一系列结构相似的带有各种短齿二膦 RPCH(R')PR 配体的三核大环铜(I)和银(I)吡唑配合物。在二膦配位后，初始配合物的平面几何结构沿着与磷部分配位的两个金属原子之间的连线发生弯曲。基于 dcpm 配体（R = 环己基，R' = H，Ph）的配合物在室温下的溶液中，在 P NMR 时间尺度上不表现出动态行为，这与之前观察到的带有 dppm（R = Ph，R' = H）骨架的类似三核铜配合物不同。所有铜(I)配合物在固态下均表现出热激活延迟荧光（TADF）行为。重要的是，在磷原子上使用脂肪族取代基而非芳香族取代基，通过消除 dppm 芳香环的 LC 态的非辐射衰变，使光致发光的量子效率（Φ）几乎提高了一倍。吡唑配体中取代基（CF 对 CH）的给电子能力更强，降低了以金属为中心的激发态的能量，使得金属对 T 态有显著影响。最后，Ag(I)配合物的发射效率约为 14%，是已知的三核银(I)吡唑同金属衍生物中最高的。
