中国科学技术大学江海龙团队报道了手性配体修饰铑纳米颗粒嵌入共价有机框架中的不对称催化作用。相关研究成果于2024年8月5日发表在《德国应用化学》。

虽然金属纳米粒子（NPs）在催化方面显示出巨大的潜力，但在金属NPs周围引入手性微环境以实现高效转化和高对映选择性仍然是一个长期的挑战。

该文中，由带有不同官能团的手性二烯配体（Lx）修饰的微小Rh NPs被引入共价有机框架（COF）中，用于芳基硼酸和硝基烯烃之间的不对称1,4-加成反应。尽管COF中的Rh NPs是非活性的，但用Lx修饰Rh NPs会产生活性的Rh-Lx界面并诱导高活性。

此外，通过改变手性二烯配体上的基团来调节Rh NPs周围的手性微环境，大大优化了对映体选择性（高达95.6%ee）。机理研究表明，Lx和硝基烯烃之间氢键相互作用的形成在由此产生的对映选择性中起着关键作用。

该项工作表明了通过手性配体修饰对金属纳米颗粒周围手性微环境调节，对非均相不对称催化的重要性。

附：英文原文

Title: Chiral Ligand-Decorated Rhodium Nanoparticles Incorporated in Covalent Organic Framework for Asymmetric Catalysis

Author: Jiangtao Yu, Ge Yang, Ming-Liang Gao, He Wang, Hai-Long Jiang

Issue&Volume: 2024-08-05

Abstract: While metal nanoparticles (NPs) have demonstrated their great potential in catalysis, introducing chiral microenvironment around metal NPs to achieve efficient conversion and high enantioselectivity remains a long-standing challenge. In this work, tiny Rh NPs, modified by chiral diene ligands (Lx) bearing diverse functional groups, are incorporated into a covalent organic framework (COF) for the asymmetric 1,4-addition reactions between arylboronic acids and nitroalkenes. Though Rh NPs hosted in the COF are inactive, decorating Rh NPs with Lx creates the active Rh-Lx interface and induces high activity. Moreover, chiral microenvironment modulation around Rh NPs by altering the groups on chiral diene ligands greatly optimizes the enantioselectivity (up to 95.6% ee). Mechanistic investigations indicate that the formation of hydrogen-bonding interaction between Lx and nitroalkenes plays critical roles in the resulting enantioselectivity. This work highlights the significance of chiral microenvironment modulation around metal NPs by chiral ligand decoration for heterogeneous asymmetric catalysis.

DOI: 10.1002/anie.202412643

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202412643