Size-Exclusion Mechanism Driving Host–GuestInteractions between Octahedral Rhenium Clusters and Cyclodextrins

In aqueous solution, cyclodextrins (CDs) are able to bind strongly either hydrophobic species or also hydrophilic molecules such as octahedral hexametallic cluster. Systematic investigation of the reactivity between native CDs (α- or β-CD) and water-soluble rhenium clusters [Re6Q8(CN)6]4– with Q = S, Se, and Te were performed, leading to six new crystal structures revealing different types of supramolecular arrangements. Encapsulation of [Re6Q8(CN)6]4– (Q = S, Se, or Te) within two β-CDs is observed regardless of the cluster size. Interestingly, different assembling scenarios are pointed out depending on the host–guest matching featured by no, partial, or deep inclusion complexes that involved either primary or secondary rim of the CD tori. In the specific case of α-CD, only the smaller cluster [Re6S8(CN)6]4– is able to form inclusion complex with the tori host. Solution investigations, using a set of complementary techniques including isothermal titration calorimetry, multinuclear NMR methods, cyclic vol...