Design, Characterizations and Host‐Guest Properties of a New Metal‐Organic Cage Based on Half‐Sandwich Rhodium Moieties

Abstract

AbstractDespite recent efforts to advance host‐guest systems using discrete metal‐organic cages (MOCs) with non‐trivial topological geometries for molecular recognition, which is often mediated by non‐covalent interactions involving aromatic functional groups, the relative complexation of these so‐called π‐π interaction is still challenges of study, theory and modeling. Specifically, the ability of supramolecular interactions, for an example, π‐π stacking between guest substrates and MOCs as hosts, would easily control the host‐guest assemblies. By the assembly of host‐guest complexations with metal‐coordination driven strategy and π‐π interaction, here we show that the hierarchical combination of the newly metal‐organic cages with nanosized cavity (metallacage 1), which facilitates encapsulating guest molecules through supramolecular forces. Additionally, the electron‐donating (ED)/‐withdrawing (EW) functional groups of pyrene analogues, utilized as guest substrates, can enforce host‐guest assemblies with electron‐donor (D) and electron‐acceptor (A) interactions. We herein demonstrate that ED or EW group can promote host‐guest behaviors. By this new approach, we predict that the more stable host‐guest complexations will be accompanied by stronger D−A interactions. Three guest substrates, including 1‐hydroxypyrene, 1‐pyrenamine, and 1‐pyrenecarboxaldehyde, were chosen to systematically study this host‐guest system within 1, exhibiting well consistent with our hypothesis.