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 voltammetry, and electrospray ionization mass spectrometry, corroborate nicely conclusions of the solid-state studies. It appears clearly that size-matching supported by solvent effects play key roles in the stability of the host-guest complexes. At last, circular dichroism studies underline that the chirality induction from cyclodextrins to the rhenium cluster depends strongly on the strength of host-guest interactions.
- CHALCOGENIDE CLUSTERS
- MOLECULAR RECOGNITION