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High Proton Conductivity by a Metal–Organic Framework Incorporating Zn8O Clusters with Aligned Imidazolium Groups Decorating the Channels

Author:
Sen, Susan, Nair, Nisanth N., Yamada, Teppei, Kitagawa, Hiroshi, Bharadwaj, Parimal K.
Source:
Journal of the American Chemical Society 2012 v.134 no.47 pp. 19432-19437
ISSN:
1520-5126
Subject:
X-ray diffraction, activation energy, fuel cells, heat, ligands, solvents
Abstract:
A novel metal–organic framework, [{(Zn₀.₂₅)₈(O)}Zn₆(L)₁₂(H₂O)₂₉(DMF)₆₉(NO₃)₂]ₙ (1) {H₂L = 1,3-bis(4-carboxyphenyl)imidazolium}, has been synthesized under solvothermal conditions in good yield. It shows a Zn₈O cluster that is coordinated to six ligands and forms an overall three-dimensional structure with channels along the crystallographic a and b axes. The imidazolium groups of the ligand moiety are aligned in the channels. The channels are not empty but are occupied by a large number of DMF and water molecules. Upon heating, these solvent molecules can be removed without breakdown of the overall structure of the framework as shown by variable-temperature powder X-ray diffraction patterns. Of great interest is the fact that the compound exhibits high proton conductivity with a low activation energy that is comparable to those of Nafion presently used in fuel cells.
Agid:
5387257