Trifluoromethylated Phenanthroline Ligands Reduce Excited-State Distortion in Homoleptic Copper(I) Complexes
Trifluoromethylated Phenanthroline Ligands Reduce Excited-State Distortion in Homoleptic Copper(I) Complexes
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DOI：
10.1021/acs.inorgchem.9b03146
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发表时间：
2020-03-02
影响因子：
4.6
通讯作者：
Rack, Jeffrey J.
中科院分区：
文献类型：
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作者：
Livshits, Maksim Y.;Reeves, Brian J.;Rack, Jeffrey J.
我们报告的合成和激发态动力学的一系列均配铜（I）三氟甲基菲咯啉配合物与两个，三个和四个三氟甲基官能团。我们的稳态吸光度和发射，瞬态吸收光谱，和电子结构理论计算结果的分析，使深入分析的伪Jahn-Teller扭曲抑制从增加的空间位阻的三氟甲基官能团相对于原型二甲基菲咯啉络合物。令人惊讶的是，我们的研究结果表明，最大程度的伪Jahn-Teller畸变抑制是实现与三氟甲基化的只有2和9的位置由一个不寻常的组合的空间位阻和稳定的非畸变（MLCT）-M-1流形观察到的瞬态动力学寿命和优化的激发态结构。2，9-二（三氟甲基）-1，10-邻菲咯啉Cu（I）配合物的系间跃迁（ISC）寿命为69 ps，三重态激发态寿命和发射量子产率分别为106 ns和4 × 10 ~（-3）。菲咯啉的进一步三氟甲基化在菲咯啉氮上产生更大的t键诱导拔出力，最终导致与铜的配位较弱。最后，2，9-双（三氟甲基）-1，10-菲咯啉Cu（I）配合物通过调节配体空间和电子性质的惊人成功概述了开发长寿命Cu（I）电荷转移配合物的新策略。
We report the synthesis and excited-state dynamics for a series of homoleptic copper(I) trifluoromethylated phenanthroline complexes with two, three, and four trifluoromethyl functional groups. Our analysis of the steady-state absorbance and emission, transient-absorption spectroscopy, and electronic-structure-theory calculations results enable in-depth analysis of the pseudo-Jahn-Teller distortion inhibition from increased steric hindrance of the trifluoromethyl functional group relative to the prototypical dimethyl phenanthroline complex. Surprisingly, our results demonstrate that the greatest degree of pseudo-Jahn-Teller distortion inhibition is achieved with trifluoromethylation of only the 2 and 9 positions by an unusual combination of steric hindrance and stabilization of a nondistorted (MLCT)-M-1 manifold observed by transient kinetic lifetimes and optimized excited-state structures. The intersystem-crossing (ISC) lifetime for the 2,9-bis(trifluoromethyl)-1,10-phenanthroline Cu(I) complex is 69 ps, while the triplet excited-state lifetime and emission quantum yield are 106 ns and 4 x 10(-3), respectively. Further trifluoromethylation of the phenanthroline yields a greater t bond inductive withdrawing force on the phenanthroline nitrogens, ultimately resulting in weaker coordination to the copper. Last, the surprising success of the 2,9-bis(trifluoromethyl)-1,10-phenanthroline Cu(I) complex by adjusting both ligand sterics and electronic properties outlines a new strategy for developing long-lived Cu(I) charge-transfer complexes.