Crystal structures and properties of large protonated water clusters encapsulated by metal-organic frameworks

Structural characterization of large ionic water cluster H[([H.sub.2]O).sub.28.sup.+], consisting of a water shell [([H.sub.2]O).sub.26] and an encaged species H[([H.sub.2]O).sup.2+] as a center core, trapped in the well-modulated cavity of a porous metal-organic framework (MOF) is reported. Direct observation of the structures of various large ionic water clusters trapped by porous MOFs, coupled with the proton/ion-exchange processes and the reversible dehydration/rehydration, provide valuable insights into the aqueous proton transfer and its mobility pertaining to the large protonated water clusters in the condensed phase.