title: Emissive osmium(II) complexes with tetradentate bis(pyridylpyrazolate) chelates.
abstract: A tetradentate bis(pyridylpyrazolate) chelate, L, is assembled by connecting two bidentate 3-(trifluoromethyl)-5-(2-pyridyl)pyrazole chelates at the 6 position of the pyridyl fragment with a phenylamido appendage. This chelate was then utilized in the synthesis of three osmium(II) complexes, namely, [Os(L)(CO)2] (4), [Os(L)(PPh2Me)2] (5), and [Os(L)(PPhMe2)2] (6). Single-crystal X-ray structural analyses were executed on 4 and 5 to reveal the bonding arrangement of the L chelate. Phosphine-substituted derivatives 5 and 6 are highly emissive in both solution and the solid state, and their photophysical properties were measured and discussed on the basis of computational approaches. For application, fabrication and analysis of organic light-emitting diodes (OLEDs) were also carried out. The OLEDs using 5 and 6 as dopants exhibit saturated red emission with maximum external quantum efficiencies of 9.8% and 9.4%, respectively, which are higher than that of the device using [Ir(piq)3] as a red-emitting reference sample. Moreover, for documentation, 5 and 6 also achieve a maximum brightness of 19540 cd·m(-2) at 800 mA·cm(-2) (11.6 V) and 12900 cd·m(-2) at 500 mA·cm(-2) (10.5 V), respectively.
authors.affiliation: Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors.forename: Shih-Han
authors.initials: SH
authors.lastname: Chang
authors.forename: Chun-Fu
authors.initials: CF
authors.lastname: Chang
authors.forename: Jia-Ling
authors.initials: JL
authors.lastname: Liao
authors.forename: Yun
authors.initials: Y
authors.lastname: Chi
authors.forename: Dong-Ying
authors.initials: DY
authors.lastname: Zhou
authors.forename: Liang-Sheng
authors.initials: LS
authors.lastname: Liao
authors.forename: Tzung-Ying
authors.initials: TY
authors.lastname: Jiang
authors.forename: Tsao-Pei
authors.initials: TP
authors.lastname: Chou
authors.forename: Elise Y
authors.initials: EY
authors.lastname: Li
authors.forename: Gene-Hsiang
authors.initials: GH
authors.lastname: Lee
authors.forename: Ting-Yi
authors.initials: TY
authors.lastname: Kuo
authors.forename: Pi-Tai
authors.initials: PT
authors.lastname: Chou
mesh_terms: D002614:Chelating Agents / Q000138:chemical synthesis / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D009992:Osmium / Q000737:chemistry*; D011720:Pyrazoles / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*
chemical_list: D002614:Chelating Agents; D009942:Organometallic Compounds; D011720:Pyrazoles; D011725:Pyridines; D009992:Osmium