Promotion of low-humidity proton conduction by controlling hydrophilicity in layered metal-organic frameworks

Masaaki Sadakiyo, Hisashi Okawa, Akihito Shigematsu, Masaaki Ohba, Teppei Yamada, Hiroshi Kitagawa

Research output: Contribution to journalArticle

212 Citations (Scopus)

Abstract

We controlled the hydrophilicity of metal-organic frameworks (MOFs) to achieve high proton conductivity and high adsorption of water under low humidity conditions, by employing novel class of MOFs, {NR 3(CH 2COOH)}[MCr(ox) 3]•nH 2O (abbreviated as R-MCr, where R = Me (methyl), Et (ethyl), or Bu (n-butyl), and M = Mn or Fe): Me-FeCr, Et-MnCr, Bu-MnCr, and Bu-FeCr. The cationic components have a carboxyl group that functions as the proton carrier. The hydrophilicity of the cationic ions was tuned by the NR 3 residue to decrease with increasing bulkiness of the residue: {NMe 3(CH 2COOH)} + > {NEt 3(CH 2COOH)} + > {NBu 3(CH 2COOH)} +. The proton conduction of the MOFs increased with increasing hydrophilicity of the cationic ions. The most hydrophilic sample, Me-FeCr, adsorbed a large number of water molecules and showed a high proton conductivity of ∼10 -4 S cm -1, even at a low humidity of 65% relative humidity (RH), at ambient temperature. Notably, this is the highest conductivity among the previously reported proton-conducting MOFs that operate under low RH conditions.

Original languageEnglish
Pages (from-to)5472-5475
Number of pages4
JournalJournal of the American Chemical Society
Volume134
Issue number12
DOIs
Publication statusPublished - Mar 28 2012

All Science Journal Classification (ASJC) codes

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

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