Controlling the chirality of Metallo-cages by Manipulating the Stereochemistry of the Metal Centers

Abstract

Precise control over the chirality of metallo-cages by maniplating the stereochemistry of metal centers is important in many practical applications, but is extremely challenging. In this study, two isostructural metallo-cuboctahedra (1-ZnII12L18 and 2-CdII12L18) have been assembled using ligand L1 and two kinds of metal ions (ZnII and CdII) with similar coordination lability. The chiral-induction by the same guests (D-/L-camphorsulfonate, D-/L-SCS) results in a completely opposing stereochemical output of 1 and 2: D-SCS induced host-guest complex of [D-SCS⊂Δ12-1] and [D-SCS⊂Λ12-2], respectively, with reverse handedness. The distinct stereochemical configuration of metallo-cuboctahedra can be manipulated by participant metal ions that exhibit similar dynamics. Furthermore, a subtle variation of the ligand peripheral substituent group facilitates spontaneous resolution of metallo-cuboctahedra 3-ZnII12L28 from a racemic mixture as (R24, Λ12)-3/(S24, Δ12)-3 enantiopure entities. The dynamic stereochemistry of MII12L8 cuboctahedra described in this work allows a chiral manipulation based on the nature of metal centers and ligands, enabling the design and control of the chirality of metallo-cages.