Diphenyl(1-naphthyl)phosphine Ancillary for Assembling of Red and Orange-Emitting Ir(III) Based Phosphors; Strategic Synthesis, Photophysics, and Organic Light-Emitting Diode Fabrication

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• 作者：Bo-Sian Du ; Chen-Huey Lin ; Yun Chi ; Jui-Yi Hung ; Min-Wen Chung ; Tsung-Yi Lin ; Gene-Hsiang Lee ; Ken-Tsung Wong ; Pi-Tai Chou ; Wen-Yi Hung ; Hao-Chih Chiu
• 刊名：Inorganic Chemistry
• 出版年：2010
• 出版时间：October 4, 2010
• 年：2010
• 卷：49
• 期：19
• 页码：8713-8723
• 全文大小：1119K
• 年卷期：v.49,no.19(October 4, 2010)
• ISSN：1520-510X

文摘

Treatment of a series of dinuclear Ir(III) complexes [(fnazo)₂Ir(μ-Cl]₂, [(fpiq)₂Ir(μ-Cl]₂, and [(fppy)₂Ir(μ-Cl]₂ with diphenyl(1-naphthyl)phosphine (dpnH) in decalin at 100 °C afforded the simple adducts, trans-N,N′-[(fnazo)₂Ir(dpnH)Cl] (1a), trans-N,N′-[(fpiq)₂Ir(dpnH)Cl] (1b), and trans-N,N′-[(fppy)₂Ir(dpnH)Cl] (1c), for which the CN cyclometalating reagents, that is, fnazoH, fpiqH and fppyH, stands for 4-(4-fluorophenyl)quinazoline, 1-(4-fluorophenyl)isoquinoline and 4-fluorophenylpyridine, respectively. Single crystal X-ray diffraction study on 1a revealed existence of two trans-N,N′ cyclometalates, with both chloride and dpnH donors located at the positions opposite to the phenyl substituents. Subsequent heating of 1a−1c at higher temperature afforded the second isomer (2a−2c), showing formation of cis-N,N′ orientation for the aforementioned cyclometalates. Further thermolysis of either trans or cis-Ir(III) complexes 1 or 2 in presence of sodium acetate, which serves as both activator and chloride scavenger, gave successful isolation of a mixture of two fully cyclometalated Ir(III) complexes trans-N,N′-[(CN)₂Ir(dpn)] (3a−3c) and cis-N,N′-[(CN)₂Ir(dpn)] (4a−4c). Structural and photophysical properties of complexes 3a−3c and 4a−4c were measured and compared. Time-dependent density functional theory (DFT) studies suggested that, upon changing the CN cyclometalates from quinazolinyl, isoquinolinyl, and, finally, to pyridyl fragment, the lowest unoccupied molecular orbitals (LUMOs) are gradually shifted from the cyclometalating nitrogen heterocycles to the 1-naphthyl group of the phosphine chelate and, concomitantly altered the photophysical properties. An organic light-emitting diode (OLED) using orange-red phosphors 4a and 4b has been successfully fabricated. At the practical brightness of 500 cd·m⁻², decent external quantum efficiency of 10.6% and 12.5% could be reached for 4a and 4b, respectively, revealing the usefulness of relevant molecular architecture in designing triplet OLED emitters.