四川大学向海峰团队开发出桥接两方平面铂(II)配合物实现高磷光平面手性的方法。相关研究成果发表在2022年1月20日出版的《美国化学会杂志》。

手性金属有机配合物已显示出许多潜在的实际应用。然而，为正方形平面配合物建立金属诱导的手性仍然是一个巨大的挑战，因为它们的二维平面分子结构通常可以叠加在它们的镜像上。

该文中，研究人员报道了一种通过构建三维双层分子结构来实现新型平面手性的简单而有效的方法。用非手性配体1,3,4-恶二唑-2-硫醇（OXT）桥联两个方形平面配合物，得到一对外消旋R/S平面手性双核Pt（II）配合物，可通过手性高效液相色谱（HPLC）进行分离。此外，使用手性（R）-/（S）-联萘衍生的OXT配体，可以制备对映体纯R,R,R或S,S,S络合物，非对映选择性为99%，无需使用手性HPLC。联萘基团有助于确保良好的溶解性和光滑的非晶态薄膜形态，但对光物理性质影响不大。

合成的配合物显示出强烈的橙红色和近红外磷光，量子产率高达83.4%，可作为高效溶液处理有机发光二极管的发射器，实现亮度、亮度效率、外部量子效率，不对称因子高达3.22×104 cd m^–2，28.7cdA^-1、14.3%和2.0×10^-3。综合考虑EL效率和不对称因素，这是基于Pt（II）络合物的圆极化OLED中性能最好的。

研究工作为建立平面手性的手性光学和圆极化发光应用提供了一个新的和简单的策略。

附：英文原文

Title: Highly Phosphorescent Planar Chirality by Bridging Two Square-Planar Platinum(II) Complexes: Chirality Induction and Circularly Polarized Luminescence

Author: Jintong Song, Hui Xiao, Lizhi Fang, Lang Qu, Xiangge Zhou, Zong-Xiang Xu, Cheng Yang, Haifeng Xiang

Issue&Volume: January 20, 2022

Abstract: Chiral organometallic complexes have demonstrated many potential and practical applications. However, building metal-induced chirality for square-planar complexes still remains a big challenge, because their 2D planar molecular structures are usually superimposable on their mirror images. Herein, we report a straightforward and efficient way to achieve a novel kind of planar chirality by constructing 3D double-layer molecular structures. When the achiral ligand 1,3,4-oxadiazole-2-thiol (OXT) was used to bridge two square-planar complexes, a pair of racemic R/S planar-chiral binuclear Pt(II) complexes was obtained, which could be separated by chiral high-performance liquid chromatography (HPLC). Moreover, enantiopure R,R,R or S,S,S complexes could be prepared by the use of chiral (R)-/(S)-binaphthalene-derived OXT ligands in 99% diastereoselectivity without the use of chiral HPLC. The binaphthalene groups help to ensure good solubility and a smooth amorphous thin film morphology but have little effect on the photophysical properties. The resultant complexes display strong orange-red and near-infrared phosphorescence with quantum yields of up to 83.4% and can be applied as emitters in highly efficient solution-processed organic light-emitting diodes to achieve luminance, luminance efficiency, external quantum efficiency, and an asymmetry factor of up to 3.22 × 104 cd m–2, 28.7 cd A–1, 14.3%, and 2.0 × 10–3, respectively. With a comprehensive consideration of EL efficiency and the asymmetry factor, this is the best performance among Pt(II) complex based circularly polarized OLEDs. Therefore, this work provides a new and simple strategy to build planar chirality for chiroptical and circularly polarized luminescence applications.

DOI: 10.1021/jacs.1c11699

Source: https://pubs.acs.org/doi/10.1021/jacs.1c11699