Wong Keith Man-Chung, Hung Ling-Ling, Lam Wai Han, Zhu Nianyong, Yam Vivian Wing-Wah
Centre for Carbon-Rich Molecular and Nano-Scale Metal-Based Materials Research and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong.
J Am Chem Soc. 2007 Apr 11;129(14):4350-65. doi: 10.1021/ja068264u. Epub 2007 Mar 16.
A new class of luminescent cyclometalated alkynylgold(III) complexes, [Au(RC=N(R')=CR)(CCR' ')], i.e., [Au(C=N=C)(C triple bond CR'')] (HC=N=CH = 2,6-diphenylpyridine) R' ' = C6H5 1, C6H4-Cl-p 2, C6H4-NO2-p 3, C6H4-OCH3-p 4, C6H4-NH2-p 5, C6H4-C6H13-p 6, C6H13 7, [Au(tBuC=N=CtBu)(C triple bond CC6H5)] 8 (HtBuC=N=CtBuH = 2,6-bis(4-tert-butylphenyl)pyridine), and [Au(C=NTol=C)(CCC6H4-C6H13-p)] 9 (HC=NTol=CH = 2,6-diphenyl-4-p-tolylpyridine), have been synthesized and characterized. The X-ray crystal structures of most of the complexes have also been determined. Electrochemical studies show that, in general, the first oxidation wave is an alkynyl ligand-centered oxidation, while the first reduction couple is ascribed to a ligand-centered reduction of the cyclometalated ligand with the exception of 3 in which the first reduction couple is assigned as an alkynyl ligand-centered reduction. Their electronic absorption and luminescence behaviors have also been investigated. In dichloromethane solution at room temperature, the low-energy absorption bands are assigned as the pi-pi* intraligand (IL) transition of the cyclometalated RC=N(R')=CR ligand with some mixing of a [pi(C triple bond CR'') --> pi*(RC=N(R')=CR)] ligand-to-ligand charge transfer (LLCT) character. The low-energy emission bands of all the complexes, with the exception of 5, are ascribed to origins mainly derived from the pi-pi* IL transition of the cyclometalated RC=N(R')=CR ligand. In the case of 5 that contains an electron-rich amino substituent on the alkynyl ligand, the low-energy emission band was found to show an obvious shift to the red. A change in the origin of emission is evident, and the emission of 5 is tentatively ascribed to a [pi(CCC6H4NH2) --> pi*(C=N=C)] LLCT excited-state origin. DFT and TDDFT computational studies have been performed to verify and elucidate the results of the electrochemical and photophysical studies.
一类新型的发光环金属化炔基金(III)配合物,即[Au(RC=N(R')=CR)(CCR'')],也就是[Au(C=N=C)(C≡CR'')](HC=N=CH = 2,6 - 二苯基吡啶),R'' = C6H5 1、C6H4 - Cl - p 2、C6H4 - NO2 - p 3、C6H4 - OCH3 - p 4、C6H4 - NH2 - p 5、C6H4 - C6H13 - p 6、C6H13 7、[Au(tBuC=N=CtBu)(C≡CC6H5)] 8(HtBuC=N=CtBuH = 2,6 - 双(4 - 叔丁基苯基)吡啶)以及[Au(C=NTol=C)(CCC6H4 - C6H13 - p)] 9(HC=NTol=CH = 2,6 - 二苯基 - 4 - 对甲苯基吡啶)已被合成并表征。大多数配合物的X射线晶体结构也已确定。电化学研究表明,一般来说,第一个氧化波是以炔基配体为中心的氧化,而第一个还原偶归因于环金属化配体以配体为中心的还原,但3除外,其中第一个还原偶被指定为以炔基配体为中心的还原。它们的电子吸收和发光行为也已被研究。在室温下的二氯甲烷溶液中,低能量吸收带被指定为环金属化的RC=N(R')=CR配体的π - π配体内(IL)跃迁,并伴有一定程度的[π(C≡CR'')→π(RC=N(R')=CR)]配体到配体电荷转移(LLCT)特征。除5外,所有配合物的低能量发射带主要归因于环金属化的RC=N(R')=CR配体的π - π* IL跃迁。对于在炔基配体上含有富电子氨基取代基的5,发现其低能量发射带明显向红色移动。发射起源发生了明显变化,5的发射暂归因于[π(CCC6H4NH2)→π*(C=N=C)] LLCT激发态起源。已进行密度泛函理论(DFT)和含时密度泛函理论(TDDFT)计算研究以验证并阐明电化学和光物理研究结果。