Synthesis and photoluminescence properties of four rhenium(I) complexes based on diimine ligands with oxadiazole/carbazole moiety
作者:Jing Wu、Hong-Yan Li、Ling-Chen Kang、Dong-Ping Li、Huan-Rong Li、Xin-Hui Zhou、Yan Sui、You-Xuan Zheng、Jing-Lin Zuo、Xiao-Zeng You
DOI:10.1016/j.jphotochem.2010.02.010
日期:2010.4
By introducing two carrier-transporting moieties (oxadiazole and carbazole) into two diimine ligands (2-(2-pyridine)-benzimidazole and 2,2'-dipyridylamine), respectively, four novel ligands (L1-L4) and their corresponding rhenium(I) complexes (1-4) have been synthesized and characterized by elemental analysis, H-1 NMR and IR spectra. Their photophysical properties, thermal analysis, along with the X-ray crystal structure analysis of 14 and corresponding complex 4 are also described. In absorption spectra, the 2-(2-pyridine)benzimidazole containing complexes 1,2 show the intraligand charge-transfer (pi -> pi* (L)) bands and metal-to-ligand charge-transfer d pi(Re) -> pi* MLCT bands, while the 2,2'-dipyridylamine containing complexes 3,4 only show the pi -> pi* bands. In the excitation spectra, all the complexes show strong M La bands. After excitation of pi -> pi* or MLCT bands, all the four Re(I) complexes exhibit broad bands around 550-560 nm due to the Re(I)-based (MLCT)-M-3 emission. The two complexes 1 (with oxadiazole moiety) and 2 (with carbazole moiety) show the photoluminescence quantum efficiency of 2.0% and 7.5% in solid state, respectively, indicating that the carbazole unit is the better chromophore to enhance the luminescence efficiency of diimine Re(I) complexes than the oxadiazole moiety. (C) 2010 Elsevier B.V. All rights reserved.