"Host in Host" Supramolecular Core-Shell Type Systems Based on Giant Ring-Shaped Polyoxometalates

Angew Chem Int Ed Engl. 2021 Jun 14;60(25):14146-14153. doi: 10.1002/anie.202102507. Epub 2021 Mar 31.

Abstract

Herein, we show how the chaotropic effect arising from reduced molybdate ions in acidified aqueous solution is able to amplify drastically weak supramolecular interactions. Time-resolved Small Angle X-ray Scattering (SAXS) analysis suggests that molybdenum-blue oligomeric species form huge aggregates in the presence of γ-cyclodextrin (γ-CD) which results in the fast formation of nanoscopic {Mo154 }-based host-guest species, while X-ray diffraction analysis reveals that the ending-point of the scenario results in an unprecedented three-component well-ordered core-shell-like motif. A similar arrangement was found by using preformed hexarhenium chalcogenide-type cluster [Re6 Te8 (CN)6 ]4- as exogenous guest. This seminal work brings better understanding of the self-assembly processes in general and gives new opportunities for practical applications in the design of complex multicomponent materials via the simplicity of the non-covalent chemistry.

Keywords: clusters; cyclodextrin; inclusion compounds; polyoxometalates (POMs); supramolecular chemistry.