A Chiral-at-Metal Magnetic Complex Inside an Enantiopure Magnetic Cage Framework

Abstract

The integration of chirality and magnetism into discrete metal–organic architectures remains a formidable synthetic challenge, particularly when both the cage framework and the encapsulated complex are chiral and paramagnetic. This challenge lies in controlling the stereochemistry of both components while establishing pathways for magnetic exchange between their paramagnetic metal centers within a discrete host–guest assembly. In this paper, we report a new series of enantiopure paramagnetic trigonal bipyramidal Co^II₅L₆ cage frameworks, which are templated by twin carbonate ions or a chiral-at-metal magnetic [M(C₂O₄)₃]^n– complex (M = Cr^III, n = 3 or M = Co^II, n = 4) inside. The incorporation of the chiral-at-metal complex inside the cage alters the chiroptical properties compared with the Co^II₅L₆ framework encaging carbonate ions. Furthermore, the cage framework and the encapsulated chiral-at-metal complex exhibit significant magnetic interactions. The variation of the metal types in the encapsulated chiral-at-metal complex or the cage frameworks can modulate the magnetic interactions, from antiferromagnetism to ferromagnetism with different exchange strengths. This study provides a new option for the design of cage materials combining chirality and magnetism.