title: Os(II) phosphors with near-infrared emission induced by ligand-to-ligand charge transfer transition.
abstract: Heating of Os3(CO)12 with 6 equiv of 2-(3-(trifluoromethyl)-1H-1,2,4-triazol-5-yl) pyridine (fptzH) in refluxing diethylene glycol monomethyl ether, followed by sequential treatment with stoichiometric Me3NO and addition of PPhMe2, afforded two isomeric mixtures of red-emitting [Os(fptz)2(PPhMe2)2] (1T and 1C), for which the notations T and C stand for the trans and cis-oriented fptz chelates, respectively. Alternatively, preparation of Os(II) complex using a 1:1 mixture of 5,5'-di(trifluoromethyl)-3,3'-di-1,2,4-triazole (dttzH2) and 2,2'-bipyridine (bpy), instead of fptzH, gave isolation of a mononuclear Os(II) complex [Os(bpy)(dttz)(CO)2] (2) in moderate yield. Replacement of CO with PPhMe2 on 2 afforded near-infrared (NIR)-emitting Os(II) complex [Os(bpy)(dttz)(PPhMe2)2] (3). The single-crystal X-ray structural analyses were executed on 1C, 2, and 3 to reveal the structural influence imposed by the various chelates. The photophysical and electrochemical properties were measured and discussed using the results of density functional theory (DFT) and time-dependent DFT calculations. Complex 3 is selected as the dopant to probe its electroluminescent properties by fabrication of the NIR emitting organic light-emitting diodes.
authors.affiliation: Department of Chemistry and Low Carbon Energy Research Center, National Tsing Hua University , Hsinchu 30013, Taiwan.
authors.forename: Jia-Ling
authors.initials: JL
authors.lastname: Liao
authors.forename: Yun
authors.initials: Y
authors.lastname: Chi
authors.forename: Shih-Hung
authors.initials: SH
authors.lastname: Liu
authors.forename: Gene-Hsiang
authors.initials: GH
authors.lastname: Lee
authors.forename: Pi-Tai
authors.initials: PT
authors.lastname: Chou
authors.forename: Hao-Xiang
authors.initials: HX
authors.lastname: Huang
authors.forename: Yu-De
authors.initials: YD
authors.lastname: Su
authors.forename: Chih-Hao
authors.initials: CH
authors.lastname: Chang
authors.forename: Jin-Sheng
authors.initials: JS
authors.lastname: Lin
authors.forename: Meu-Rurng
authors.initials: MR
authors.lastname: Tseng