Complexation of Polyoxometalates with Cyclodextrins

By Wu, Yilei; Shi, Rufei; Wu, Yi-Lin; Holcroft, James M.; Liu, Zhichang; Frasconi, Marco; Wasielewski, Michael R.; Li, Hui & Stoddart, J. Fraser
Published in Journal of the American Chemical Society NULL 2015

Abstract

Although complexation of hydrophilic guests inside the cavities of hydrophobic hosts is considered to be unlikely, we demonstrate herein the complexation between γ- and β-cyclodextrins (γ- and β-CDs) with an archetypal polyoxometalate (POM)—namely, the [PMO??O?0]3- trianion—which has led to the formation of two organic-inorganic hybrid 2:1 complexes, namely [La(H?O)9]{[PMO??O?0]⊂[γ-CD]2} (CD-POM-1) and [La(H?O)9] {[PMO??O?0]⊂[β-CD]2} (CD-POM-2), in the solid state. The extent to which these complexes assemble in solution has been investigated by (i) 1H, 13C, and 31P NMR spectroscopies and (ii) small- and wide-angle X-ray scattering, as well as (iii) mass spectrometry. Single-crystal X-ray diffraction reveals that both complexes have a sandwich-like structure, wherein one [PMO??O?0]3- trianion is encapsulated by the primary faces of two CD tori through intermolecular [C-H···O═Mo] interactions. X-ray crystal superstructures of CD-POM-1 and CD-POM-2 show also that both of these 2:1 complexes are lined up longitudinally in a one-dimensional col

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