Abstract

Although chirality is an ever-present characteristic in biology and some artificial molecules, controlling the chirality and demystifying the chirality origin of complex assemblies remain challenging. Herein, we report two homochiral Ag14 nanoclusters with inherent chirality originated from identical rotation of six square faces on a Ag8 cube driven by intra-cluster π···π stacking interaction between pntp− (Hpntp = p-nitrothiophenol) ligands. The spontaneous resolution of the racemic (SD/rac-Ag14a) to homochiral nanoclusters (SD/L-Ag14 and SD/R-Ag14) can be realized by re-crystallizing SD/rac-Ag14a in acetonitrile, which promotes the homochiral crystallization in solid state by forming C–H···O/N hydrogen bonds with nitro oxygen atoms in pntp− or aromatic hydrogen atoms in dpph (dpph = 1,6-bis(diphenylphosphino)hexane) on Ag14 nanocluster. This work not only provides strategic guidance for the syntheses of chiral silver nanoclusters in an all-achiral environment, but also deciphers the origin of chirality at molecular level by identifying the special effects of intra- and inter-cluster supramolecular interactions.

Highlights

  • Chirality is an ever-present characteristic in biology and some artificial molecules, controlling the chirality and demystifying the chirality origin of complex assemblies remain challenging

  • As revealed by singlecrystal X-ray diffraction (SCXRD), the inherent chirality of Ag14 nanocluster originates from identical rotational directionality of six square faces on Ag8 cube, which is mainly driven by intracluster π···π stacking interaction between pntp− ligands, while homochiral crystallization is promoted by C–H···O/N hydrogen bonds formed between lattice acetonitrile and the nitro oxygen atoms in pntp− or aromatic hydrogen atoms in dpph on Ag14 nanocluster

  • The inherent chirality of Ag14 nanocluster is induced by identical rotational directionality of six square faces of Ag8 cube, which is locked by π···π interaction between pntp− ligands, maintaining the chirality in solid state

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Summary

Introduction

Chirality is an ever-present characteristic in biology and some artificial molecules, controlling the chirality and demystifying the chirality origin of complex assemblies remain challenging. As revealed by singlecrystal X-ray diffraction (SCXRD), the inherent chirality of Ag14 nanocluster originates from identical rotational directionality of six square faces on Ag8 cube, which is mainly driven by intracluster π···π stacking interaction between pntp− ligands, while homochiral crystallization is promoted by C–H···O/N hydrogen bonds formed between lattice acetonitrile and the nitro oxygen atoms in pntp− or aromatic hydrogen atoms in dpph on Ag14 nanocluster. The enantiomeric conglomerates show mirrorimaged circular dichroism (CD) and circularly polarized luminescence (CPL) responses These results give us precise answers at molecular-level to (i) How to desymmetrize the highly symmetrical polyhedral silver nanocluster to become a chiral one; (ii) what is responsible for the chirality of the overall molecule; (iii) what is the driving force to enantioseparate racemates during the crystallization

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