Confined water-mediated high proton conduction in hydrophobic channel of a synthetic nanotube

Ken ichi Otake, Kazuya Otsubo*, Tokutaro Komatsu, Shun Dekura, Jared M. Taylor, Ryuichi Ikeda, Kunihisa Sugimoto, Akihiko Fujiwara, Chien Pin Chou, Aditya Wibawa Sakti, Yoshifumi Nishimura, Hiromi Nakai, Hiroshi Kitagawa

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

101 Citations (Scopus)


Water confined within one-dimensional (1D) hydrophobic nanochannels has attracted significant interest due to its unusual structure and dynamic properties. As a representative system, water-filled carbon nanotubes (CNTs) are generally studied, but direct observation of the crystal structure and proton transport is difficult for CNTs due to their poor crystallinity and high electron conduction. Here, we report the direct observation of a unique water-cluster structure and high proton conduction realized in a metal-organic nanotube, [Pt(dach)(bpy)Br]4(SO4)4·32H2O (dach: (1R, 2R)-(–)-1,2-diaminocyclohexane; bpy: 4,4’-bipyridine). In the crystalline state, a hydrogen-bonded ice nanotube composed of water tetramers and octamers is found within the hydrophobic nanochannel. Single-crystal impedance measurements along the channel direction reveal a high proton conduction of 10−2 Scm−1. Moreover, fast proton diffusion and continuous liquid-to-solid transition are confirmed using solid-state 1H-NMR measurements. Our study provides valuable insight into the structural and dynamical properties of confined water within 1D hydrophobic nanochannels.

Original languageEnglish
Article number843
JournalNature communications
Issue number1
Publication statusPublished - 2020 Dec 1

ASJC Scopus subject areas

  • General Chemistry
  • General Biochemistry,Genetics and Molecular Biology
  • General Physics and Astronomy


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