Ogino Yasuyo, Kusamoto Tetsuro, Hattori Yohei, Shimada Masaki, Tsuchiya Mizuho, Yamanoi Yoshinori, Nishibori Eiji, Sugimoto Kunihisa, Nishihara Hiroshi
Department of Chemistry, Graduate School of Science, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Division of Physics, Faculty of Pure and Applied Sciences, Tsukuba Research Center for Interdisciplinary Materials Science (TIMS) &, Center for Integrated Research in Fundamental Science and Engineering (CiRfSE), University of Tsukuba , Tsukuba, Ibaraki 305-8571, Japan.
Inorg Chem. 2017 Apr 3;56(7):3909-3915. doi: 10.1021/acs.inorgchem.6b02864. Epub 2017 Mar 15.
A paramagnetic, luminescent organometallic gold(I) complex Au(CF)(PyBTM), where PyBTM is a photostable fluorescent polychlorinated diphenyl(4-pyridyl)methyl radical, was prepared, and its crystal and electronic structures and magnetic and optical properties were investigated. Magnetic studies using electron spin resonance spectroscopy and a superconducting quantum interference device magnetometer indicated the existence of S = / spin per molecule, with the spin density distributed mainly on the PyBTM ligand. The complex exhibited fluorescence in CHCl with emission peak wavelength (λ) of 619 nm and the absolute fluorescence quantum yield (ϕ) of 0.04, confirming that Au(CF)(PyBTM) is the first luminescent organometallic complex with a coordinated luminescent radical. Solvent-dependent unique luminescent characteristics were observed in halogenated solvents (CCl, CHCl, CHCl, and ClCHCHCl). ϕ decreased, and λ shifted to longer wavelengths as the polarity (dielectric constant) of the solvent increased. Notably, the complex in CCl displayed fluorescence with ϕ = 0.23, which was quite high in radicals, while showed dual fluorescence in CHCl and ClCHCHCl with lifetimes of around 1 and 7 ns for two emissive components. Density functional theory (DFT) and time-dependent (TD)-DFT calculations indicated that the fluorescence occurred from an interligand charge transfer (CT) excited state in CCl, in which the CF and PyBTM moieties acted as electron donor and acceptor, respectively, while the fluorescence was centered at the PyBTM ligand in the other three solvents. This method, i.e., the formation of an interligand CT state, to enhance ϕ is distinctly different from the methods reported previously. The present study revealed that a coordination bond is available for forming emissive CT excited states that lead to high ϕ, providing a novel method with greater capability for realizing highly emissive radicals.
制备了一种顺磁性、发光的有机金属金（I）配合物Au（CF）（PyBTM），其中PyBTM是一种光稳定的荧光多氯代二苯基（4-吡啶基）甲基自由基，并对其晶体结构、电子结构以及磁学和光学性质进行了研究。使用电子自旋共振光谱和超导量子干涉仪磁力计进行的磁性研究表明，每个分子存在S = 1/2自旋，自旋密度主要分布在PyBTM配体上。该配合物在CHCl₃中表现出荧光，发射峰波长（λ）为619 nm，绝对荧光量子产率（ϕ）为0.04，证实Au（CF）（PyBTM）是首个具有配位发光自由基的发光有机金属配合物。在卤代溶剂（CCl₄、CHCl₃、CH₂Cl₂和ClCH₂CH₂Cl）中观察到了溶剂依赖性的独特发光特性。随着溶剂极性（介电常数）的增加，ϕ降低，λ移向更长波长。值得注意的是，该配合物在CCl₄中显示出荧光，ϕ = 0.23，这在自由基中相当高，而在CHCl₃和ClCH₂CH₂Cl中表现出双重荧光，两个发射组分的寿命分别约为1和7 ns。密度泛函理论（DFT）和含时（TD）-DFT计算表明，在CCl₄中荧光源于配体间电荷转移（CT）激发态，其中CF和PyBTM部分分别作为电子供体和受体，而在其他三种溶剂中荧光则以PyBTM配体为中心。这种通过形成配体间CT态来提高ϕ的方法与先前报道的方法明显不同。本研究表明，配位键可用于形成导致高ϕ的发射性CT激发态，为实现高发射性自由基提供了一种具有更大能力的新方法。
