Journal of the American Chemical Society
Journal of the American Chemical Society
3 years ago

[ASAP] Assembly of Chiral Cluster-Based Metal–Organic Frameworks and the Chirality Memory Effect during their Disassembly

[ASAP] Assembly of Chiral Cluster-Based Metal–Organic Frameworks and the Chirality Memory Effect during their Disassembly
Guocheng Deng, Boon K. Teo, Nanfeng Zheng
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 (Ag14) 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-Ag14m and S-Ag14m. 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]n (Ag14-LR), [Ag14(SPh(CF3)2)12(PPh3)4(LS)2]n (Ag14-LS), and [Ag14(SPh(CF3)2)12(PPh3)4(LRS)2]n (Ag14-LRS), respectively. As expected, the building blocks in Ag14-LR or Ag14-LS are homochiral R-Ag14 or S-Ag14, respectively. In contrast, Ag14-LRS is achiral and crystallizes with a diamond-like structure containing alternate R-Ag14 and S-Ag14 clusters. During the assembly process, the racemic Ag14 clusters were converted to homochiral building blocks, namely, R-Ag14 for Ag14-LR and S-Ag14 for Ag14-LS. Subsequently, the chiral linkers were removed from the crystals of Ag14-LR and Ag14-LS via hydrolysis with water, and from the disassembled solid material Ag14-DR and Ag14-DS, optically pure enantiomers R-Ag14m and S-Ag14m 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. The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/jacs.1c03251. Figures of 1H and 13C NMR spectra, CD spectra, crystal structures, tetrahedron structures, PXRD, UV–vis spectra, fluorescence spectra, CPL spectra, packing diagram, intensity changes, FT-IR spectra, and Arrhenius plot ln(k) vs 1/T and tables of crystal data and structure refinement (PDF) This article has not yet been cited by other publications.

Publisher URL: http://feedproxy.google.com/~r/acs/jacsat/~3/jEzkfT-w5Qs/jacs.1c03251

DOI: 10.1021/jacs.1c03251

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