Hasegawa Tatsuya, Kobayashi Atsushi, Ohara Hiroki, Yoshida Masaki, Kato Masako
Department of Chemistry, Faculty of Science, Hokkaido University , North-10 West-8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan.
Inorg Chem. 2017 May 1;56(9):4928-4936. doi: 10.1021/acs.inorgchem.6b03122. Epub 2017 Apr 10.
We have synthesized two luminescent mononuclear Cu(I) complexes, Cu(PPhTol)(THF)(4Mepy) (1) and Cu(PPhTol)(4Mepy) (2) (PPhTol = diphenyl(o-tolyl)phosphine, 4Mepy = 4-methylpyridine, THF = tetrahydrofuran), and investigated their crystal structures, luminescence properties, and vapor-induced ligand exchange reactions in the solid state. Both coordination complexes are tetrahedral, but one of the three 4Mepy ligands of complex 2 is replaced by a THF solvent molecule in complex 1. In contrast to the very weak blue emission of the THF-bound complex 1 (wavelength of emission maximum (λ) = 457 nm, emission quantum yield (Φ) = 0.02) in the solid state at room temperature, a very bright blue-green emission was observed for 2 (λ = 484 nm, Φ = 0.63), suggesting a contribution of the THF ligand to nonradiative deactivation. Time-dependent density functional theory calculations and emission lifetime measurements suggest that the room-temperature emissions of the complexes are due to thermally activated delayed fluorescence from the metal-to-ligand charge transfer excited state. Interestingly, by exposing the solid sample of THF-bound 1 to 4Mepy vapor, the emission intensity drastically increased and the emission color changed from blue to blue-green. Powder X-ray diffraction measurements revealed that the emission change of 1 is due to the vapor-induced ligand exchange of THF for 4Mepy, forming the strongly emissive complex 2. Further emission tuning was achieved by exposing 1 to pyrimidine or pyrazine vapors, forming green (λ = 510 nm) or orange (λ = 618 nm) emissive complexes, respectively. These results suggest that the vapor-induced ligand exchange is a promising method to control the emission color of luminescent Cu(I) complexes.
我们合成了两种发光单核铜（I）配合物，Cu(PPhTol)(THF)(4Mepy)（1）和Cu(PPhTol)(4Mepy)（2）（PPhTol = 二苯基（邻甲苯基）膦，4Mepy = 4-甲基吡啶，THF = 四氢呋喃），并研究了它们的晶体结构、发光性质以及固态下的气相诱导配体交换反应。两种配位配合物均为四面体结构，但配合物2的三个4Mepy配体中的一个在配合物1中被一个THF溶剂分子取代。与室温下固态时THF配位的配合物1的非常微弱的蓝色发射（发射最大值波长（λ） = 457 nm，发射量子产率（Φ） = 0.02）形成对比，配合物2观察到非常明亮的蓝绿色发射（λ = 484 nm，Φ = 0.63），这表明THF配体对非辐射失活有贡献。含时密度泛函理论计算和发射寿命测量表明，配合物的室温发射是由于从金属到配体电荷转移激发态的热激活延迟荧光。有趣的是，通过将THF配位的1的固体样品暴露于4Mepy蒸气中，发射强度急剧增加，发射颜色从蓝色变为蓝绿色。粉末X射线衍射测量表明，1的发射变化是由于THF与4Mepy的气相诱导配体交换，形成了强发射配合物2。通过将1暴露于嘧啶或吡嗪蒸气中，分别形成绿色（λ = 510 nm）或橙色（λ = 618 nm）发射配合物，实现了进一步的发射调谐。这些结果表明，气相诱导配体交换是控制发光铜（I）配合物发射颜色的一种有前景方法。
