Proton-conductive magnetic metal-organic frameworks, {NR 3(CH2COOH)}[MaIIMb III(ox)3]: Effect of carboxyl residue upon proton conduction

Hisashi Okawa, Masaaki Sadakiyo, Teppei Yamada, Mitsuhiko Maesato, Masaaki Ohba, Hiroshi Kitagawa

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Abstract

Proton-conductive magnetic metal-organic frameworks (MOFs), {NR 3(CH2COOH)}[MaIIMb III(ox)3] (abbreviated as R-MaMb: R = ethyl (Et), n-butyl (Bu); MaMb = MnCr, FeCr, FeFe) have been studied. The following six MOFs were prepared: Et-MnCr·2H 2O, Et-FeCr·2H2O, Et-FeFe·2H2O, 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 {NBu3(CH2COOH)}+ ions. Et-MnCr·2H2O and Bu-MnCr (R-MnCr MOFs) show a ferromagnetic ordering with TC of 5.5-5.9 K, and Et-FeCr·2H2O and Bu-FeCr (R-FeCr MOFs) also show a ferromagnetic ordering with TC of 11.0-11.5 K. Et-FeFe·2H2O 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·2H2O, Et-FeCr·2H2O and Et-FeFe·2H2O) 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.

Original languageEnglish
Pages (from-to)2256-2262
Number of pages7
JournalJournal of the American Chemical Society
Volume135
Issue number6
DOIs
Publication statusPublished - Feb 13 2013
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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