title: High proton conductivity by a metal-organic framework incorporating Zn8O clusters with aligned imidazolium groups decorating the channels.
abstract: A novel metal-organic framework, [{(Zn(0.25))(8)(O)}Zn(6)(L)(12)(H(2)O)(29)(DMF)(69)(NO(3))(2)](n) (1) {H(2)L = 1,3-bis(4-carboxyphenyl)imidazolium}, has been synthesized under solvothermal conditions in good yield. It shows a Zn(8)O 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.
authors.affiliation: Department of Chemistry, Indian Institute of Technology, Kanpur 208016, India.
authors.forename: Susan
authors.initials: S
authors.lastname: Sen
authors.forename: Nisanth N
authors.initials: NN
authors.lastname: Nair
authors.forename: Teppei
authors.initials: T
authors.lastname: Yamada
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kitagawa
authors.forename: Parimal K
authors.initials: PK
authors.lastname: Bharadwaj