Temperature Dependence of Blue Phosphorescent Cyclometalated Ir(III) Complexes.
The photophysical properties for a series of facial (fac) cyclometalated Ir(III) complexes (fac-Ir(C^N) (C^N = 2-phenylpyridyl (ppy), 2-(4,6-difluorophenyl)pyridyl (F2ppy), 1 -phenylpyrazolyl (ppz), 1-(2,4-difluorophenyl)pyrazolyl) (F2ppz), and 1-(2-(9,9′-dimethylfluorenyl))pyrazolyl (fIz)), fac-lr(...
| Publicado en: | Journal of the American Chemical Society Vol. 131; no. 28; pp. 9813 - 9823 |
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| Autores principales: | , , , , , |
| Formato: | Artículo |
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American Chemical Society
7/22/2009
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| Materias: | |
| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=43815288&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 43815288 longDbName: Humanities International Complete uiTag: AN controlInfo: bkinfo: jinfo: jid: 00027863 ACS jtl: Journal of the American Chemical Society issn: 00027863 maglogo: N pubinfo: dt: 7/22/2009 vid: 131 iid: 28 pid: 997 pub: American Chemical Society artinfo: ui: 43815288 10.1021/ja903317w ppf: 9813 ppct: 10 formats: tig: atl: Temperature Dependence of Blue Phosphorescent Cyclometalated Ir(III) Complexes. aug: au: Sajoto, Tissa Djurovich, Peter I. Tamayo, Arnold B. Oxgaard, Jonas Goddard III, William A. Thompson, Mark E. affil: Department of Chemistry, University of Southern California, Los Angeles, California 90089 Department of Chemistry, California Institute of Technology, Pasadena, California 91125 su: Photophores Density functionals Ligands (Chemistry) Biochemistry Immobilized ligands (Biochemistry) Low temperatures Mathematical complexes sug: subj: Photophores Density functionals Ligands (Chemistry) Biochemistry Immobilized ligands (Biochemistry) Low temperatures Mathematical complexes ab: The photophysical properties for a series of facial (fac) cyclometalated Ir(III) complexes (fac-Ir(C^N) (C^N = 2-phenylpyridyl (ppy), 2-(4,6-difluorophenyl)pyridyl (F2ppy), 1 -phenylpyrazolyl (ppz), 1-(2,4-difluorophenyl)pyrazolyl) (F2ppz), and 1-(2-(9,9′-dimethylfluorenyl))pyrazolyl (fIz)), fac-lr(C^N)(C^N′) (C^N = ppz or F2ppz and C^N′ = ppy or F2ppy), and fac-Ir(C^C′)3 (C^C′ = 1-phenyl-3-methylbenzimidazolyl (pmb)) have been studied in dilute 2-methyltetrahydrofuran (2-MeTHF) solution in a temperature range of 77-378 K. Photoluminescent quantum yields (Φ) for the 10 compounds at room temperature vary between near zero and unity, whereas all emit with high efficiency at low temperature (77 K). The quantum yield for fac-Ir(ppy) (Φ = 0.97) is temperature-independent. For the other complexes, the temperature-dependent data indicates that the luminescent efficiency is primarily determined by thermal deactivation to a nonradiative state. Activation energies and rate constants for both radiative and nonradiative processes were obtained using a Boltzmann analysis of the temperature-dependent luminescent decay data. Activation energies to the nonradiative state are found to range between 1600 and 4800 cm. The pre-exponential factors for deactivation are large for complexes with C^N ligands (10-10 s) and significantly smaller for fac-Ir(pmb) (10 s). The kinetic parameters for decay and results from density functional theory (DFT) calculations of the triplet state are consistent with a nonradiative process involving Ir-N (Ir-C for fac-Ir(pmb)) bond rupture leading to a five-coordinate species that has triplet metal-centered (MC) character. Linear correlations are observed between the activation energy and the energy difference calculated for the emissive and MC states. The energy level for the MC state is estimated to lie between 21 700 and 24 000 cm for the fac-Ir(C^N) complexes and at 28 000 cm for fac-Ir(pmb). pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2009 holdings: @attributes: islocal: N |
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