Topology Switching in Polymetallic Fragments Governed by Metal Encapsulation

Metallosupramolecular assemblies are promising platforms for selective extraction, catalysis, and molecular recognition, yet their solution-phase synthesis often relies on complex self-assembly pathways that can be difficult to control. Here, using ion mobility mass spectrometry supported by density functional theory calculations, we introduce a gas-phase approach for directing topology in polymetallic complexes based on the encapsulation of coordination metal cations within a homometallic {Cr₈} ring. Upon inclusion, the resulting host-guest complexes undergo collision-induced dissociation to produce distinct polymetallic fragments whose topologies, ring, host-guest complex or open chain, depend on the identity of the guest cation. This topology switching enables the targeted synthesis of new polymetallic rings, host-guest complexes and open chains in vacuo and provides insight into the stoichiometric and conformational preferences of such assemblies.