Novel bright blue emissions IIB group complexes constructed with various polyhedron-induced 2-[2′-(6-methoxy-pyridyl)]-benzimidazole derivatives
作者:Shuo Chen、Rui-Qing Fan、Xin-Ming Wang、Yu-Lin Yang
DOI:10.1039/c4ce00382a
日期:——
Five IIB group complexes, [ZnL1Cl2] (1), [CdL1Cl2]}2 (2), [Cd(L1)2(NO3)2]·H2O (3), [HgL1Cl2] (4), and [ZnL2Cl2] (5) [L1 = 1-[2-(6-methoxy-2-pyridylmethyl)]-2-[2-(6-methoxy-pyridyl)]benzimidazole; L2 = 2-[2-(6-methoxypyridyl)]benzimidazole] have been synthesized and structurally characterized by elemental analysis, IR spectroscopy, 1H NMR, 13C NMR and X-ray single-crystal analyses. The structural investigations testify that the ionic radius and counterions (Clâ and NO3â) cooperatively affect the coordination mode of central metal. As small and medium radii, four-coordinated Zn2+ (1 and 5) and five-coordinated Cd2+ (2) possess tetrahedron and trigonal bipyramid geometries, respectively. Though Hg2+ (4) has a larger radius, its three-coordinated geometry is trigonal planar in order to eliminate repulsive forces. Further observations illustrate that Cd2+ (3) is bound to two ligands L1 when NO3â is the counter anion, forming seven-coordinated monocapped trigonal prismatic geometry. Complexes 1â5 display bright blue luminescence with the emission maxima (λmax) ranging from 399 to 499 nm at 298 K, depending on the N,Nâ²-chelating ligand-centered Ï* â Ï transition. Upon cooling to 77 K, the complexes show rich structured emission profiles compared to those at 298 K. The emission lifetimes of L and 1â5 are on the microsecond scale. The emission efficiency of 1â5 is shown by quantum yields ranging from 0.23 to 0.40. Complexes 1â5 offer a good insight into the opportunities in the utilization of blue materials for application and function.
合成了五种 IIB 族配合物:[ZnL1Cl2] (1)、[CdL1Cl2]}2 (2)、[Cd(L1)2(NO3)2]Â-H2O (3)、[HgL1Cl2] (4) 和 [ZnL2Cl2] (5) [L1 = 1-[2-(6-甲氧基-2-吡啶基甲基)]-2-[2-(6-甲氧基吡啶基)]苯并咪唑;合成了 L2 = 2-[2-(6-甲氧基吡啶基)]苯并咪唑,并通过元素分析、红外光谱、1H NMR、13C NMR 和 X 射线单晶分析对其结构进行了表征。结构研究证明,离子半径和反离子(Clâ 和 NO3â)会共同影响中心金属的配位模式。作为中小半径,四配位的 Zn2+ (1 和 5)和五配位的 Cd2+ (2)分别具有四面体和三叉双锥体的几何结构。虽然 Hg2+ (4) 的半径较大,但为了消除排斥力,其三配位几何形状为三棱平面。进一步的观察表明,当 NO3â 为反阴离子时,Cd2+(3)与两个配体 L1 结合,形成七配位的单帽三棱柱几何形状。配合物 1â5 显示出明亮的蓝色荧光,在 298 K 时,发射最大值(δ "max)在 399 至 499 nm 之间,这取决于 N,Nâ²-螯合配体的中心 Ï* â Ï 转变。冷却到 77 K 时,与 298 K 时相比,复合物显示出丰富的结构发射曲线。1â5 的量子产率从 0.23 到 0.40 不等,显示了其发射效率。络合物 1â5 为利用蓝色材料的应用和功能提供了良好的机会。