American Chemical Society
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Mechanistic Investigation of Improved Syntheses of Iridium(III)-Based OLED Phosphors

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posted on 2016-02-20, 19:59 authored by Cheng-Huei Lin, Yuan-Chieh Chiu, Yun Chi, Yu-Tai Tao, Liang-Sheng Liao, Meu-Rurng Tseng, Gene-Hsiang Lee
Treatment of [IrCl3(tht)3] (tht = tetrahydrothiophene) with a stoichiometric amount of PPh3 gave the monosubstitution product [Ir­(tht)2(PPh3)­Cl3] (5), whose synthesis, particularly that leading to the effective preparation of OLED phosphors, was studied and optimized to achieve the best product yields. Thus, the independent treatment of 5 with 2,4-difluorophenylpyridine (dfppyH) or with variable amounts of benzyldiphenylphosphine (bdpH) gave rise to the formation of the cyclometalation products [Ir­(dfppy)­(tht)­(PPh3)­Cl2] (7), [Ir­(bdp)­(bdpH)­(tht)­Cl2] (8), and [Ir­(bdp)­(PPh3)­(tht)­Cl2] (10), depending on the stoichiometry and conditions employed. Upon further treatment with 5-pyridyl-3-trifluoromethyl-1H-pyrazole (fppzH), these Ir­(III) complexes 7, 8, and 10 were capable of yielding the phosphors [Ir­(dfppy)­(fppz)2] (1), [Ir­(bdp)2(fppz)] (4), and [Ir­(bdp)­(fppz)2] (2), respectively. The general mechanism en route to their formation was studied and discussed.