Microscopic chiral pockets in a tris(chelated) iridium(III) complex as sites for dynamic enantioselective quenching
Microscopic chiral pockets in a tris(chelated) iridium(III) complex as sites for dynamic enantioselective quenching
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DOI：
10.1039/c7nj04688j
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发表时间：
2018-03
影响因子：
3.3
通讯作者：
Kazuyoshi Takimoto;K. Tamura;Y. Watanabe*;A. Yamagishi;Hisako Sato
中科院分区：
文献类型：
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作者：
Kazuyoshi Takimoto;K. Tamura;Y. Watanabe*;A. Yamagishi;Hisako Sato
描述了开发具有对映选择性的手性发光探针的尝试。合成了具有大配体 [Ir(bzq)2(phen)]+（bzqH = 苯并[h]喹啉；phen = 1,10-菲咯啉）的三（螯合）铱（III）配合物，并光学拆分为 Δ- 和 Λ- 对映体。该络合物（表示为 Ir(III)）在非极性有机溶剂中具有发射性，而在非质子和质子极性溶剂中发射性较低。当Ir(III)被合成皂石(记为SAP)的胶体颗粒吸附时，即使在含水溶剂中也能恢复其发射能力。通过添加 [Ru(acac)3]（acac = 乙酰丙酮，表示为 Ru(III)）来猝灭 SAP 吸附的 Ir(III) 的发射。斯特恩-沃尔默常数（KSV）表现出显着的立体选择性；对于 Δ-Ir(III)/Δ-[Ru(acac)3]（或 Λ-Ir(IIII)/Λ-[Ru(acac)3]），KSV = 15 900 ± 900 M−1；对于 Δ-Ir(III)/Λ-[Ru(acac)3]，KSV = 7000 ± 500 M−1（或Λ-Ir(III)/Δ-[Ru(acac)3])。发射寿命对 Ru(III) 浓度的依赖性表明猝灭是动态进行的。根据分子模型，假设吸附的 Ir(III) 顶部被大配体包围的微观口袋充当区分接近分子的手性的位点。
An attempt to develop a chiral luminescent probe with enantioselectivity is described. A tris(chelated) iridium(III) complex with bulky ligands, [Ir(bzq)2(phen)]+ (bzqH = benzo[h]quinoline; phen = 1,10-phenanthroline), was synthesized and optically resolved into Δ- and Λ-enantiomers. The complex (denoted as Ir(III)) was emissive in non-polar organic solvents, while in aprotic and protic polar solvents it was less emissive. When Ir(III) was adsorbed by the colloidal particles of synthetic saponite (denoted as SAP), it recovered its emitting capability even in a solvent containing water. Emission from Ir(III) adsorbed by SAP was quenched by adding [Ru(acac)3] (acac = acetylacetonato, denoted as Ru(III)). The Stern–Volmer constant (KSV) exhibited remarkable stereoselectivity; KSV = 15 900 ± 900 M−1 for Δ-Ir(III)/Δ-[Ru(acac)3] (or Λ-Ir(IIII)/Λ-[Ru(acac)3]) and 7000 ± 500 M−1 for Δ-Ir(III)/Λ-[Ru(acac)3] (or Λ-Ir(III)/Δ-[Ru(acac)3]). The dependence of the emission lifetime on the concentration of Ru(III) indicated that quenching proceeded dynamically. On the basis of the molecular model, it was postulated that a microscopic pocket surrounded by the bulky ligands at the top of adsorbed Ir(III) acted as a site discriminating the chirality of an approaching molecule.