Supramolecular Host–Guest Assemblies of [M₆Cl₁₄]^2–, M = Mo, W, Clusters with γ-Cyclodextrin for the Development of CLUSPOMs

Abstract

Host–guest assemblies open up opportunities for developing novel functional CLUSPOM multicomponent systems based on transition metal clusters (CLUS), polyoxometalates (POMs) and macrocyclic organic ligands. In water–ethanol solution γ-cyclodextrin (γ-CD) interacts with halide metal clusters [M6Cl14]2– (M = Mo, W) to form sandwich-type structures. The supramolecular association between the clusters and CDs, however, remains weak in solution, and the interactions are not strong enough to prevent the hydrolysis of the inorganic guest. Although analysis of the resulting crystal structures reveals inclusion complexation, 1H NMR experiments in solution show no specific affinity between the two components. The luminescent properties of the host–guest compounds in comparison with the initial cluster complexes are also studied to evaluate the influence of CD.

Keywords

• molybdenum
• tungsten
• octahedral cluster complexes
• γ-cyclodextrin
• luminescence
• crystal structure