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Diastereoselective Synthesis and Photophysical Properties of Bis-Cyclometalated Ir(III) Stereoisomers with Dual Stereocenters
Organometallics ( IF 2.5 ) Pub Date : 2017-08-24 00:00:00 , DOI: 10.1021/acs.organomet.7b00406
Li-Ping Li 1 , Su-Yang Yao 1 , Yan-Ling Ou 1 , Lian-Qiang Wei 1 , Bao-Hui Ye 1
Affiliation  

Diastereoselective synthesis of bis-cyclometalated Ir(III) stereoisomers Δ/Λ-[Ir(CN)2(d-pro)] and Δ/Λ-[Ir(CN)2(l-pro)] (where CN is 2-phenylpyridine (Hppy), (4,6-difluorophenyl)pyridine (Hdfppy), and 2-phenylquinoline (Hpq) and pro is proline) with dual stereogenic centers at the metal and auxiliary ligand has been developed. The diastereomers Λ-l and Λ-d, and Δ-l and Δ-d exhibit distinguishable photophysical properties in both solution and the solid state. The thermodynamically stable diastereomers Λ-[Ir(ppy)2(l-pro)], Λ-[Ir(dfppy)2(l-pro)], and Λ-[Ir(pq)2(l-pro)] emit a green emission at 524 nm (Φ = 3.5% and τ = 35 ns), a blue-green emission at 480 nm (Φ = 4.5% and τ = 59 ns), and a red emission at 588 nm (Φ = 6.5% and τ = 200 ns) in DCM solution, respectively, which are blue-shifted accompanied by a large quantum yield and long lifetime relative to the corresponding unstable diastereomers Δ-[Ir(ppy)2(l-pro)] at 537 nm (Φ = 2.3% and τ = 29 ns), Δ-[Ir(dfppy)2(l-pro)] at 489 nm (Φ = 2.8% and τ = 43 ns), and Δ-[Ir(pq)2(l-pro)] at 591 nm (Φ = 5.4% and τ = 192 ns). Similar cases were also observed in crystals, but the signals were significantly red-shifted with respect to those in solution. Single-crystal structural analyses show that the Δ-l and Λ-d diastereomers exhibit larger interligand repulsion and loose molecular packing with respect to the Δ-d and Λ-l diastereomers, resulting in energy and photophysical property differences. In addition, the isomers with Δ and Λ configurations at the metal center exhibit positive and negative circularly polarized luminescence (CPL) signals, respectively, indicating that the effects of the chiral carbon atoms in pro ligands on CPL signals are negligible.

中文翻译:

具有双立体中心的双环金属化Ir(III)立体异构体的非对映选择性合成及其光物理性质

双-环金属化铱(III)的非对映选择性合成的立体异构体Δ/Λ-的[Ir(C N)2d -pro)]和Δ/Λ-的[Ir(C N)2-Pro)](其中ç N是2-苯基吡啶(Hppy),(4,6-二氟苯基)吡啶(Hdfppy)和2-苯基喹啉(HPQ)和pro是脯氨酸)具有双立体中心在金属和辅助配已经研制成功。非对映体Λ-和Λ- d,和Δ-和Δ- ð表现出在两种溶液和固态区分的光物理特性。热力学稳定的非对映异构体Λ-[Ir(ppy)2l-pro)],Λ-[Ir(dfppy)2l -pro)]和Λ-[Ir(pq)2l -pro )]在524 nm处发出绿色发射(Φ= 3.5%,τ= 35 ns),分别在DCM溶液中的480 nm处的蓝绿色发射(Φ= 4.5%和τ= 59 ns)和588 nm处的红色发射(Φ= 6.5%和τ= 200 ns),分别是蓝移伴随着大量的量子产率和相对长的寿命为相应的非对映体不稳定Δ-[的Ir(ppy)2-pro)]在537纳米(Φ= 2.3%和τ= 29纳秒),Δ-[ Ir(dfppy)2l- pro)]在489 nm(Φ= 2.8%和τ= 43 ns)和Δ-[Ir(pq)2l-pro)]在591 nm(Φ= 5.4%,τ= 192 ns)。在晶体中也观察到类似的情况,但是信号相对于溶液中的信号明显红移。单晶体结构分析表明,相对于Δ - d和Λ- 1非对映异构体,Δ - 1和Λ- d非对映异构体表现出更大的配体排斥力和疏松的分子堆积,导致能量和光物理性质差异。此外,在金属中心具有Δ和Λ构型的异构体分别显示正和负圆偏振发光(CPL)信号,表明原配体中的手性碳原子对CPL信号的影响可忽略不计。
更新日期:2017-08-24
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