| Autor: |
Tsuchiya, Kazuyoshi, Yagai, Shiki, Kitamura, Akihide, Karatsu, Takashi, Endo, Kyoko, Mizukami, Junji, Akiyama, Seiji, Yabe, Masayoshi |
| Zdroj: |
European Journal of Inorganic Chemistry; February 2010, Vol. 2010 Issue: 6 p926-933, 8p |
| Abstrakt: |
Substitution effects on the photoluminescence and electrochemical properties and the photochemical stability of trisphenylbenzimidazolinatoIrIIIcomplexes were investigated. Facial and meridional isomers of a series of complexes having the general structure of IrC C3, where C C is 4Rphenylbenzimidazolinato R = H, CF3, CN, OCH3, were prepared. They are abbreviated to Irpmb31, IrCF3pmb32, IrCNpmb33, and IrOpmb34, respectively. Electrondonating or withdrawing groups on the phenyl ring lead to both higher emission quantum yields and longer emission lifetimes compared to those of 1in each merand facseries. 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 merb isomers of Irpmb3, IrCF3pmb3, and IrCNpmb3on irradiation with a 313nm wavelength light from a 400 W mercury lamp for more than 20 h. All complexes excluding facIrpmb31a show excellent photochemical stability in degassed anhydrous thf solution. The locations of the HOMO and LUMO and the lowest excitation energy of these complexes were investigated by DFT and TDDFT calculations on fac and merIrOpmb34aand 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 Xray single crystal structures obtained for facIrCF3pmb32a and merIrOpmb34b are also discussed. |
| Databáze: |
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