標題: Strategic design and synthesis of osmium(II) complexes bearing a single pyridyl azolate pi-chromophore: Achieving high-efficiency blue phosphorescence by localized excitation
作者: Cheng, Yi-Ming
Li, Elise Y.
Lee, Gene-Hsiang
Chou, Pi-Tai
應用化學系
Department of Applied Chemistry
公開日期: 26-十一月-2007
摘要: We present the strategic design and synthesis of Os(II) complexes bearing a single pyridyl azolate T-chromophore with an aim to attain high efficiency blue phosphorescence by way of localized transition. It turns out that our proposal of localized excitation seems to work well upon anchoring a single)T-chromophore on the Os(II) complexes such that the control of MLCT versus pi pi* (or even LLCT) transitions is more straightforward. Among the titled complexes, [OS(CO)(3)(tfa)(fppz)] (1) and [Os(CO)(3)(tfa)(fbtz)] (5) (tfa = trifluoroacetate, (fppz)H = 3-(trifluoromethyl)5-(2-pyridyl)pyrazole, and (fbtz)H = 3-(trifluoromethyl)-5-(4-tert-butyl-2-pyridyl)-1,2,4-triazole) give the anticipated blue phosphorescence with efficiencies of 0.26 (lambda(max) = 460 nm) and 0.27 (lambda(max) = 450 nm), respectively. For their halide analogues [Os(CO)(3)(X)(fppz)] (2, X = Cl; 3, X Br; 4, X = 1) and phosphine-substituted isomeric derivatives [Os(tfa)(fppz)(PPh(2)Me)(2)(CO)] (6-8), the localization of the excitation energy seems to populate at certain vibrational modes with weak bonding strength and hence an associated shallow potential energy surface to induce a facile radiationless transition. Furthermore, their ancillary ligands play an important role in fine-tuning not only the energy gap but also the emission intensity, i.e., in manifesting the radiationless transition pathways. Our results clearly show that there is always a tradeoff upon varying the parameters in an aim to optimize the hue and efficiency of phosphorescence toward blue.
URI: http://dx.doi.org/10.1021/ic7015269
http://hdl.handle.net/11536/10105
ISSN: 0020-1669
DOI: 10.1021/ic7015269
期刊: INORGANIC CHEMISTRY
Volume: 46
Issue: 24
起始頁: 10276
結束頁: 10286
顯示於類別:期刊論文


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