title: Proton-conductive magnetic metal-organic frameworks, {NR3(CH2COOH)}[M(a)(II)M(b)(III)(ox)3]: effect of carboxyl residue upon proton conduction.
abstract: Proton-conductive magnetic metal-organic frameworks (MOFs), {NR(3)(CH(2)COOH)}[M(a)(II)M(b)(III)(ox)(3)] (abbreviated as R-M(a)M(b): R = ethyl (Et), n-butyl (Bu); M(a)M(b) = MnCr, FeCr, FeFe) have been studied. The following six MOFs were prepared: Et-MnCr·2H(2)O, Et-FeCr·2H(2)O, Et-FeFe·2H(2)O, Bu-MnCr, Bu-FeCr, and Bu-FeFe. The structure of Bu-MnCr was determined by X-ray crystallography. Crystal data: trigonal, R3c (#161), a = 9.3928(13) Å, c = 51.0080(13) Å, Z = 6. The crystal consists of oxalate-bridged bimetallic layers interleaved by {NBu(3)(CH(2)COOH)}(+) ions. Et-MnCr·2H(2)O and Bu-MnCr (R-MnCr MOFs) show a ferromagnetic ordering with T(C) of 5.5-5.9 K, and Et-FeCr·2H(2)O and Bu-FeCr (R-FeCr MOFs) also show a ferromagnetic ordering with T(C) of 11.0-11.5 K. Et-FeFe·2H(2)O and Bu-FeFe (R-FeFe MOFs) belong to the class II of mixed-valence compounds and show the magnetism characteristic of Néel N-type ferrimagnets. The Et-MOFs (Et-MnCr·2H(2)O, Et-FeCr·2H(2)O and Et-FeFe·2H(2)O) show high proton conduction, whereas the Bu-MOFs (Bu-MnCr, Bu-FeCr, and Bu-FeFe) show moderate proton conduction. Together with water adsorption isotherm studies, the significance of the carboxyl residues as proton carriers is revealed. The R-MnCr MOFs and the R-FeCr MOFs are rare examples of coexistent ferromagnetism and proton conduction, and the R-FeFe MOFs are the first examples of coexistent Néel N-type ferrimagnetism and proton conduction.
authors.affiliation: Division of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan. okawa134@ac.auone-net.jp
authors.forename: Hisashi
authors.initials: H
authors.lastname: Ōkawa
authors.forename: Masaaki
authors.initials: M
authors.lastname: Sadakiyo
authors.forename: Teppei
authors.initials: T
authors.lastname: Yamada
authors.forename: Mitsuhiko
authors.initials: M
authors.lastname: Maesato
authors.forename: Masaaki
authors.initials: M
authors.lastname: Ohba
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kitagawa
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry*; D002857:Chromium / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D008345:Manganese / Q000737:chemistry*; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011522:Protons
chemical_list: D009942:Organometallic Compounds; D011522:Protons; D002857:Chromium; D002245:Carbon Dioxide; C041069:carboxyl radical; D008345:Manganese; D007501:Iron