Kazuyoshi Tsuchiya, Shiki Yagai, Akihide Kitamura, Takashi Karatsu, Kyoko Endo, Junji Mizukami, Seiji Akiyama, Masayoshi Yabe
European Journal of Inorganic Chemistry 2010(6) 926-933 2010年2月 査読有り
Substitution effects on the photoluminescence and electrochemical properties and the photochemical stability of tris-(phenylbenzimidazolinato) Ir complexes were investigated. Facial and meridional isomers of a series of complexes having the general structure of Ir(CC) , where (CC) is (4-R-phenyl)benzimidazolinato (R = H, CF , CN, OCH ), were prepared. They are abbreviated to Ir(pmb) (1), Ir-(CF pmb) (2), Ir(CNpmb) (3), and Ir(Opmb) (4), respectively. Electron-donating or -withdrawing groups on the phenyl ring lead to both higher emission quantum, yields and longer emission lifetimes compared to those of 1 in each mer and fac series. Particularly, the emission quantum yields were high in the cases of 2a, 3a, 3b, and 4a. No photochemical isomerization was observed, in both fac- (a) and mer (b) isomers of Ir(pmb) ,Ir(CF3pmb) , and Ir(CNpmb) on irradiation with a 313-nm wavelength light from a 400 W mercury lamp for more than 20 h. All complexes excluding fac-Ir(pmb) (1a) show excellent photochemical stability in degassed anhydrous the solution. The locations of the HOMO and LUMO and the lowest excitation energy of these complexes were investigated by DFT and TD-DFT calculations on fac- and mer-Ir(Opmb) (4a and 4b). The HOMO is mainly localized over the Ir metal center and the phenyl moiety, and the LUMO mainly localized over the benzimidazole moiety. The calculated lowest: excitation energies agree with the experimental values. The X-ray single crystal structures obtained for fac-Ir(CF pmb) (2a) and mer-Ir(Opmb) (4b) are also discussed. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA. III 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3