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Updated: Oct 31, 2025

Development of Heterogeneous Enantioselective Catalysts using Chiral Metal-Organic Frameworks MOFs
Published on: January 17, 2020
Assembly of Chiral Cluster-Based Metal-Organic Frameworks and the Chirality Memory Effect during their Disassembly
Guocheng Deng1, Boon K Teo1, Nanfeng Zheng1
1Collaborative Innovation Center of Chemistry for Energy Materials, State Key Laboratory for Physical Chemistry of Solid Surfaces, National & Local Joint Engineering Research Center of Preparation Technology of Nanomaterials, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
Abstract:
Many metal clusters are intrinsically chiral but are often synthesized as a racemic mixture. By taking chiral Ag14(SPh(CF3)2)12(PPh3)4(DMF)4 (Ag) clusters with bulky thiolate ligands as an example, we demonstrate herein an interesting assembly disassembly (ASDS) strategy to obtain the corresponding, optically pure crystals of both homochiral enantiomers, R-Ag and S-Ag. The ASDS strategy makes use of two bidentate linkers with different chiral configurations, namely, (1R,2R,N1E,N2E)-N1,N2-bis(pyridin-3-ylmethylene)cyclohexane-1,2-diamine (LR) and the corresponding chiral analogue LS. For comparison, we also use the racemic mixture of equimolar of LR and LS (LRS). Three three-dimensional (3D) Ag14-based metal-organic frameworks (MOFs) were characterized by X-ray crystallography to be [Ag14(SPh(CF3)2)12(PPh3)4(LR)2] (Ag-LR), [Ag14(SPh(CF3)2)12(PPh3)4(LS)2] (Ag-LS), and [Ag14(SPh(CF3)2)12(PPh3)4(LRS)2] (Ag-LRS), respectively. As expected, the building blocks in Ag-LR or Ag-LS are homochiral R-Ag or S-Ag, respectively. In contrast, Ag-LRS is achiral and crystallizes with a diamond-like structure containing alternate R-Ag and S-Ag clusters. During the assembly process, the racemic Ag clusters were converted to homochiral building blocks, namely, R-Ag for Ag-LR and S-Ag for Ag-LS. Subsequently, the chiral linkers were removed from the crystals of Ag-LR and Ag-LS via hydrolysis with water, and from the disassembled solid material Ag-DR and Ag-DS, optically pure enantiomers R-Ag and S-Ag were obtained. It is hoped that this simple assembly strategy can be used to construct cluster-based chiral assemblage materials and that the subsequent disassembly protocol can be used to obtain optically pure chiral cluster molecules from as-prepared racemic mixtures.
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