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Updated: Jun 14, 2026

Dissolution Dynamic Nuclear Polarization Instrumentation for Real-time Enzymatic Reaction Rate Measurements by NMR
Published on: February 23, 2016
Investigation of proton dynamics and the proton transport pathway in choline dihydrogen phosphate using solid-state
Lindsay S Cahill1, Usman Ali Rana, Maria Forsyth
1Department of Physics, University of Warwick, Coventry, CV4 7AL, UK.
Abstract:
Choline dihydrogen phosphate has previously been shown to be a good ionic conductor as well as an excellent host for acid doping, leading to high proton conductivities required for e.g., electrochemical devices including proton membrane fuel cells and sensors. A combination of variable-temperature (1)H solid-state NMR and 2D NMR pulse sequences, including (31)P and (13)C CODEX and (1)H BaBa, show that the proton conduction mechanism primarily involves assisted transport via a restricted three-site motion of the phosphate unit around the P-O bond that is hydrogen bonded to the choline and exchange of protons between these anions. In other words, proton transport at ambient temperatures appears to occur most favorably along the crystallographic b axis, from phosphate dimer to dimer. At elevated temperatures exchange between the protons of the hydroxyl group on the choline cation and the hydrogen-bonded dihydrogen phosphate groups also contributes to the structural diffusion of the protons in this solid state conductor.
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