Acid-Induced Degradation of Phosphorescent Dopants for OLEDs and Its Application to the Synthesis of Tris-heteroleptic Iridium(III) Bis-cyclometalated Complexes
Acid-Induced Degradation of Phosphorescent Dopants for OLEDs and Its Application to the Synthesis of Tris-heteroleptic Iridium(III) Bis-cyclometalated Complexes
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DOI：
10.1021/ic202162q
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发表时间：
2012-01-02
影响因子：
4.6
通讯作者：
Nazeeruddin, Md. Khaja
中科院分区：
文献类型：
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作者：
Baranoff, Etienne;Curchod, Basile F. E.;Nazeeruddin, Md. Khaja
基于[Ir（2-（2，4-二氟苯基）吡啶）2（吡啶甲酸酯）]（FIrPic）的蓝色磷光有机发光二极管（OLED）的研究已经指出吡啶甲酸酯的裂解是器件不稳定的可能原因。通过加入布朗斯台德酸或刘易斯酸，我们再现了吡啶甲酸盐和乙酰丙酮酸盐辅助配体在溶液中的损失。当将盐酸加入到[Ir（（CN）-N-boolean AND）（2）（（XO）-O-boolean AND）]络合物（（CN）-N-boolean AND = 2-苯基吡啶（ppy）或2-苯基吡啶（ppy））的溶液中时，（2，4-二氟苯基）吡啶（diFppy）和（XO）-O-布尔AND =吡啶甲酸酯（pic）或乙酰丙酮酸酯（acac）），辅助配体的裂解导致氯桥连铱（III）二聚体[{Ir（（CN）-N-boolean AND）（2）（μ-Cl）}（2）]的直接形成。当使用三氟甲磺酸或三氟化硼时，加入氯化物源（此处为氯化四丁基铵）以获得相同的氯桥连铱（III）二聚体。然后，我们有利地使用该降解反应来有效合成三杂配环化铱（III）络合物[Ir（（CN 1）-N-boolean AND）（（CN 2）-N-boolean AND）（L）]，这是一个环化络合物家族，否则制备具有挑战性。我们使用铱（I）络合物[{Ir（COD）（mu-Cl）}（2）]和化学计量量的两种不同的（CN）-N-boolean AND配体（（CN 1）-N-boolean AND = ppy;（CN 2）-N-boolean AND = dIFppy）作为快速制备氯桥连铱（III）二聚体的起始材料。将混合物与乙酰丙酮反应并随后纯化后，可以从含有双混配配合物[Ir（ppy）（2）（acac）]和[Ir（diFppy）（2）（acac）]的粗产物中以良好的产率分离出三混配配合物[Ir（ppy）（diFppy）（acac）]。三混配acac配合物与盐酸反应得到纯的氯桥铱二聚体[{Ir（ppy）（diFppy）（mu-Cl）}（2）]，它可作为制备基于这两个（CN）-N-布尔AND配体的新的三混配铱（III）配合物的起始原料。最后，我们使用DFT/LR-TDDFT来合理化两种不同的（CN）-N-布尔AND配体对所观察到的物理和电化学性质的影响。
Investigations of blue phosphorescent organic light emitting diodes (OLEDs) based on [Ir(2-(2,4-difluorophenyl)pyridine)2(picolinate)] (FIrPic) have pointed to the cleavage of the picolinate as a possible reason for device instability. We reproduced the loss of picolinate and acetylacetonate ancillary ligands in solution by the addition of Bronsted or Lewis acids. When hydrochloric acid is added to a solution of a [Ir((CN)-N-boolean AND)(2)((XO)-O-boolean AND)] complex ((CN)-N-boolean AND = 2-phenylpyridine (ppy) or 2-(2,4-difluorophenyl)pyridine (diFppy) and (XO)-O-boolean AND = picolinate (pic) or acetylacetonate (acac)), the cleavage of the ancillary ligand results in the direct formation of the chloro-bridged iridium(III) dimer [{Ir((CN)-N-boolean AND)(2)(mu-Cl)}(2)]. When triflic acid or boron trifluoride are used, a source of chloride (here tetrabutylammonium chloride) is added to obtain the same chloro-bridged iridium(III) dimer. Then, we advantageously used this degradation reaction for the efficient synthesis of tris-heteroleptic cyclometalated iridium(III) complexes [Ir((CN1)-N-boolean AND)((CN2)-N-boolean AND)(L)], a family of cyclometalated complexes otherwise challenging to prepare. We used an iridium(I) complex, [{Ir(COD)(mu-Cl)}(2)], and a stoichiometric amount of two different (CN)-N-boolean AND ligands ((CN1)-N-boolean AND = ppy; (CN2)-N-boolean AND = diFppy) as starting materials for the swift preparation of the chloro-bridged iridium(III) dimers. After reacting the mixture with acetylacetonate and subsequent purification, the tris-heteroleptic complex [Ir(ppy)(diFppy)(acac)] could be isolated with good yield from the crude containing as well the bis-heteroleptic complexes [Ir(ppy)(2)(acac)] and [Ir(diFppy)(2)(acac)]. Reaction of the tris-heteroleptic acac complex with hydrochloric acid gives pure heteroleptic chloro-bridged iridium dimer [{Ir(ppy)(diFppy)(mu-Cl)}(2)], which can be used as starting material for the preparation of a new tris-heteroleptic iridium(III) complex based on these two (CN)-N-boolean AND ligands. Finally, we use DFT/LR-TDDFT to rationalize the impact of the two different (CN)-N-boolean AND ligands on the observed photophysical and electrochemical properties.