Highly phosphorescent iridium complexes containing both tridentate bis(benzimidazolyl)-benzene or -pyridine and bidentate phenylpyridine: Synthesis, photophysical properties, and theoretical study of Ir-bis(benzimidazolyl) benzene complex
Highly phosphorescent iridium complexes containing both tridentate bis(benzimidazolyl)-benzene or -pyridine and bidentate phenylpyridine: Synthesis, photophysical properties, and theoretical study of Ir-bis(benzimidazolyl) benzene complex
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DOI：
10.1021/ic060796o
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发表时间：
2006-10-30
影响因子：
4.6
通讯作者：
Haga, Masa-aki
中科院分区：
文献类型：
--
作者：
Obara, Shinya;Itabashi, Masumi;Haga, Masa-aki
新型混合配体 Ir( III) 配合物，[ Ir( L)( N 布尔值 AND C) X](n+) ( L) N 布尔值 AND C 布尔值 AND N 或 N 布尔值 AND N 布尔值 AND N； X) Cl、Br、I、CN、CH3CN 或 -CCPh； n) 0 或 1)，其中 N 布尔值 AND C 布尔值 AND N) 双(N-甲基苯并咪唑基)苯 (Mebib) 和双(N-苯基苯并咪唑基)苯 (Phbib)、N 布尔值 AND N 布尔值 AND N) 双(N-甲基苯并咪唑基)吡啶 (Mebip) 和 N 布尔值 AND C) 苯基吡啶 (ppy) 衍生物。 [Ir(Phbib)(ppy)Cl]和[Ir(Mebib)(mppy)Cl][mppy)5-甲基-2-(2'-吡啶基)苯基]的X射线晶体结构表明ppy配体的氮原子位于Me-或Phbib中配位碳原子的反式位置，而ppy中的配位碳原子占据Cl的反式位置。 [Ir(Mebip)(ppy)Cl](+)在+1.05V处显示准可逆Ir(III/IV)氧化波，而Ir络合物[Ir(Mebib)(ppy)Cl]相对于Fc/Fc(+)在+0.42V处被氧化。在[Ir(Mebib)(ppy)Cl]中引入Ir-C键会引起负方向0.63V的大电势偏移。此外，[Ir(Mebib)(Rppy) X]的氧化电位通过R、R'和X基团的取代而改变。与氧化电位相比，第一还原电位显示出几乎恒定的值，[Ir(L)(ppy)Cl](L)Mebib 和 Phbib) 为 - 2.36 至 -2.46 V，[Ir(Mebip)(ppy) Cl 为 - 1.52 V。 [Ir(Mebib)(R-ppy) X]的紫外可见光谱显示在 407 nm 附近有清晰的单线态金属到配体电荷转移跃迁，类似于 425 nm，在 498 nm 处显示出三线态金属到配体电荷转移跃迁，类似于 523 nm。 [ Ir(Mebip)(ppy) Cl] + 在 610 nm 处发射，室温下发光量子产率为 Phi = 0.16。在室温下，[Ir(Mebib)(ppy)X]在526 nm处观察到X) CN的磷光，在555 nm处观察到X) Cl的磷光，具有高发光量子产率，Phi = 0.77，类似于0.86，在室温下。 [Ir(Phbib)(ppy)Cl]在559 nm处发射，发光量子产率为0.95，与其他发射金属配合物相比，这是一个前所未有的高值。与 Ir( ppy) 2( L) 衍生物和 [ Ir( Mebip)( ppy) Cl](+) 的发光量子产率相比，中性 Ir 配合物 [ Ir( L)( R-ppy) X] ( L) Me- 或 Phbib) 表现出非常高的量子产率和大辐射速率常数 ( k(r)) 范围从 3.4 x 10(5) 到 5.5 x 10（5） s(-1)。密度泛函理论计算表明这些Ir配合物主要具有金属到配体电荷转移和卤化物到配体电荷转移激发态。本文从使用微扰理论和一中心自旋轨道耦合近似的辐射速率常数的理论考虑的角度讨论了[Ir(bib)(ppy)X]中高磷光产率的机制。
Novel mixed-ligand Ir( III) complexes, [ Ir( L)( N boolean AND C) X](n+) ( L) N boolean AND C boolean AND N or N boolean AND N boolean AND N; X) Cl, Br, I, CN, CH3CN, or - CCPh; n) 0 or 1), were synthesized, where N boolean AND C boolean AND N) bis( N-methylbenzimidazolyl) benzene ( Mebib) and bis( N-phenylbenzimidazolyl) benzene ( Phbib), N boolean AND N boolean AND N) bis( N-methylbenzimidazolyl) pyridine ( Mebip), and N boolean AND C) phenylpyridine ( ppy) derivatives. The X-ray crystal structures of [ Ir( Phbib)( ppy) Cl] and [ Ir( Mebib)( mppy) Cl] [ mppy) 5-methyl-2-( 2'-pyridyl) phenyl] indicate that the nitrogen atom of the ppy ligand is located trans to the coordinating carbon atom in Me- or Phbib, while the coordinating carbon atom in ppy occupies the trans position of Cl. [ Ir( Mebip)( ppy) Cl](+) showed a quasireversible Ir( III/IV) oxidation wave at + 1.05 V, while the Ir complexes, [ Ir( Mebib)( ppy) Cl], were oxidized at + 0.42 V versus Fc/Fc(+). The introduction of an Ir - C bond in [ Ir( Mebib)( ppy) Cl] induces a large potential shift of 0.63 V in a negative direction. Further, the oxidation potential of [ Ir( Mebib)( Rppy) X] was altered by the substitution of R, R', and X groups. Compared to the oxidation potential, the first reduction potential revealed an almost constant value at - 2.36 to - 2.46 V for [ Ir( L)( ppy) Cl] ( L) Mebib and Phbib) and - 1.52 V for [ Ir( Mebip)( ppy) Cl. The UV-vis spectra of [ Ir( Mebib)( R-ppy) X] show a clear singlet metal-to-ligand charge-transfer transition around 407 similar to 425 nm and a triplet metal-to-ligand charge-transfer transition at 498 similar to 523 nm. [ Ir( Mebip)( ppy) Cl] + emits at 610 nm with a luminescent quantum yield of Phi = 0.16 at room temperature. The phosphorescence of [ Ir( Mebib)( ppy) X] was observed at 526 nm for X) CN and 555 nm for X) Cl with the high luminescent quantum yields, Phi = 0.77 similar to 0.86, at room temperature. [ Ir( Phbib)( ppy) Cl] shows the emission at 559 nm with a luminescent quantum yield of) 0.95, which is an unprecedentedly high value compared to those of other emissive metal complexes. Compared to the luminescent quantum yields of the Ir( ppy) 2( L) derivatives and [ Ir( Mebip)( ppy) Cl](+), the neutral Ir complexes, [ Ir( L)( R-ppy) X] ( L) Me- or Phbib), reveal very high quantum yields and large radiative rate constants ( k(r)) ranging from 3.4 x 10(5) to 5.5 x 10(5) s(-1). The density functional theory calculation suggests that these Ir complexes possess dominantly metal-to-ligand charge-transfer and halide-to-ligand charge-transfer excited states. The mechanism for a high phosphorescence yield in [ Ir( bib)( ppy) X] is discussed herein from the perspective of the theoretical consideration of radiative rate constants using perturbation theory and a one-center spin - orbit coupling approximation.