Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.
Chemistry. 2010 Dec 10;16(46):13773-82. doi: 10.1002/chem.201000793.
A new class of readily tunable isocyano rhenium(I) diimine luminophores, cis,cis-Re(CO)(2)(CNR)(2)(N-N) (R=2,4,6-Cl(3)C(6)H(2), 4-ClC(6)H(4), 4-Br-2,6-(CH(3))(2)C(6)H(2), 2,6-(CH(3))(2)C(6)H(3), 4-[(CH(3))(2)N]C(6)H(4), 4-(C(6)H(5))C(6)H(4), 4-nBuC(6)H(4), tBu), has been synthesized in high yield by a highly selective photochemical substitution reaction. These complexes were characterized by (1)H NMR and IR spectroscopy, mass spectrometry, and elemental analysis. The X-ray crystal structures of one of the complexes and one of the precursor complexes for the photosubstitution reaction were also determined. As the isocyanide ligands are readily tunable, complexes with excellent solubility in benzene or other nonpolar solvents could be designed through slight modification of the isocyanide ligands with a short nBu substituent. With the characteristic strong infrared absorptions of the carbonyl (C≡O) and isocyanide (C≡N) stretches as well as the high solubility of the reactant and product in benzene, which is the solvent for the photoreaction, the photosubstitution reaction of [Re(CO)(3)(nBuC(6)H(4)NC)(2)Br] with 4,4'-di-tert-butyl-2,2'-bipyridine was also studied by in situ IR spectroscopy. The photophysical and electrochemical properties of these complexes were also investigated. Except for the complex with [(CH(3))(2)N]C(6)H(4)NC ligands, all complexes displayed intense luminescence with quantum yields of up to 0.37 in degassed CH(2)Cl(2) solution at room temperature. These emissions were assigned as the phosphorescence derived from the metal-to-ligand charge transfer [dπ(Re)→π*(N-N)] excited state. The emissive excited states of these complexes have also been characterized by transient absorption spectroscopic studies. The capability of tuning the emissive excited-state energy through the modification of the isocyanide ligands could be reflected by the significant shifting of the phosphorescence from 530 to 620 nm with the same phenanthroline ligand.
一类新型的可调节的偕二氰基铼（I）二亚胺类发光体，cis,cis-Re(CO)(2)(CNR)(2)(N-N)（R=2,4,6-Cl(3)C(6)H(2)，4-ClC(6)H(4)，4-Br-2,6-(CH(3))(2)C(6)H(2)，2,6-(CH(3))(2)C(6)H(3)，4-[(CH(3))(2)N]C(6)H(4)，4-(C(6)H(5))C(6)H(4)，4-nBuC(6)H(4)，tBu），通过高选择性的光化学取代反应，以高产率合成。这些配合物通过（1）H NMR 和 IR 光谱、质谱和元素分析进行了表征。还确定了其中一个配合物和光取代反应的一个前体配合物的 X 射线晶体结构。由于异氰化物配体很容易调节，因此通过用短的 nBu 取代基轻微修饰异氰化物配体，可以设计出在苯或其他非极性溶剂中具有优异溶解性的配合物。羰基（C≡O）和异氰化物（C≡N）伸缩的特征强红外吸收以及反应物和产物在光反应溶剂苯中的高溶解度，使[Re(CO)(3)(nBuC(6)H(4)NC)(2)Br]与 4,4'-二叔丁基-2,2'-联吡啶的光取代反应也通过原位 IR 光谱进行了研究。还研究了这些配合物的光物理和电化学性质。除了具有[(CH(3))(2)N]C(6)H(4)NC 配体的配合物外，所有配合物在室温下的脱气 CH(2)Cl(2)溶液中都显示出高达 0.37 的强发光量子产率。这些发射被归因于来自金属到配体电荷转移[dπ(Re)→π*(N-N)]激发态的磷光。通过瞬态吸收光谱研究还对这些配合物的发射激发态进行了表征。通过异氰化物配体的修饰来调节发射激发态能量的能力可以通过用相同的菲咯啉配体将磷光从 530nm 显著移动到 620nm 来反映。
