Premium
Solid‐state NMR studies of hydrogen bonding networks and proton transport pathways based on anion and cation dynamics
Author(s) -
Traer Jason W.,
Goward Gillian R.
Publication year - 2007
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.2127
Subject(s) - chemistry , alkyl , molecular dynamics , magic angle spinning , ion , hydrogen bond , adduct , solid state nuclear magnetic resonance , proton , nuclear magnetic resonance spectroscopy , proton nmr , membrane , computational chemistry , stereochemistry , molecule , organic chemistry , nuclear magnetic resonance , biochemistry , physics , quantum mechanics
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 1 H solid‐state magic angle spinning (MAS) NMR, DQ MAS NMR, and 31 P 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.