Chiral Superlattices Self-Assembled from Post-Modified Metal-Organic Polyhedra.

Abstract

Metal-organic polyhedra (MOPs) are inherently porous, discrete, and solvent-dispersive, and directing them into chiral superlattices through direct self-assembly remains a considerable challenge due to their nanoscale size and structural complexity. In this work, we illustrate a postmodification protocol to covalently conjugate a chiral cholesteryl pendant to MOPs. Postmodification retained the coordination cores and allowed for reaction-induced self-assembly in loosely packed nanosized columns without supramolecular chirality. Solvent-processed bottom-up self-assembly in aqueous media facilitated the well-defined packing into twisted superlattices with a 5 nm lattice parameter. Experimental and computational results validated the role of intercholesteryl forces in spinning the nanosized MOPs, which achieved the chirality transfer to supramolecular scale with chiral optics. This work establishes a novel protocol in rational design of MOP-based chiroptical materials for potential applications of enantioselective adsorption, catalysis, and separation.