Research Article

Solid-state NMR studies of hydrogen bonding networks and proton transport pathways based on anion and cation dynamics

  1. Jason W. Traer,
  2. Gillian R. Goward*

Article first published online: 21 DEC 2007

DOI: 10.1002/mrc.2127

Issue

Magnetic Resonance in Chemistry

Magnetic Resonance in Chemistry

Special Issue: New techniques in solid-state NMR

Volume 45, Issue S1, pages S135–S143, December 2007

Additional Information

How to Cite

Traer, J. W. and Goward, G. R. (2007), Solid-state NMR studies of hydrogen bonding networks and proton transport pathways based on anion and cation dynamics. Magn. Reson. Chem., 45: S135–S143. doi: 10.1002/mrc.2127

Author Information

  1. McMaster University, Department of Chemistry, 1280 Main St. W. Hamilton, ON, L8S 4M1, Canada

*McMaster University, Department of Chemistry, 1280 Main St. W. Hamilton, ON, L8S 4M1, Canada.

Publication History

  1. Issue published online: 21 DEC 2007
  2. Article first published online: 21 DEC 2007
  3. Manuscript Accepted: 9 OCT 2007
  4. Manuscript Revised: 5 OCT 2007
  5. Manuscript Received: 15 JUL 2007

Funded by

  • NSERC
  • National Ultrahigh Field NMR Facility for Solids (Ottawa, Canada)
  • Canada Foundation for Innovation
  • Ontario Innovation Trust
  • Recherche Québec
  • National Research Council Canada
  • Bruker BioSpin
  • University of Ottawa (www.nmr900.ca)
  • The Natural Sciences and Engineering Research Council of Canada (NSERC)

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Keywords:

  • solid-state 1H MAS NMR;
  • 31P CODEX NMR;
  • hydrogen bonding;
  • proton-conducting membranes;
  • conductivity mechanisms;
  • benzimidazole;
  • fast magic angle spinning

Abstract

Proton dynamics in polymer electrolyte membranes are multifaceted processes, and the relative contributions of various mechanisms can be difficult to distinguish. Judicious choices of model systems can aid in understanding the critical steps. In this study, we characterize anion dynamics in a series of benzimidazole-alkyl phosphonate salts, and compare those dynamics to a membrane prototype, built on a decane backbone. The series of salts are characterized, using high resolution 1H solid-state magic angle spinning (MAS) NMR, DQ MAS NMR, and 31P centreband-only detection of exchange (CODEX) NMR spectroscopy, to determine the influence of the nature of the alkyl group on the rates and geometries of anion dynamics, and overall proton exchange processes. The alkyl group is shown to slow the correlation times for anion reorientation, when compared at ambient temperature. However, it is also apparent that the lowered lattice energy of the salt lowers the activation energy and allows good dynamics at intermediate temperatures in both the benzimidazolium ethylphosphonate and in the HBr adduct of 1,10-(1-H-imidazol-5-yl)decanephosphonic acid (Imi-d-Pa). Copyright © 2007 John Wiley & Sons, Ltd.

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