TY - JOUR
T1 - NMR Characterization of Ionicity and Transport Properties for a Series of Diethylmethylamine Based Protic Ionic Liquids
AU - Davidowski, Stephen K.
AU - Thompson, Forrest
AU - Huang, Wei
AU - Hasani, Mohammad
AU - Amin, Samrat A.
AU - Angell, Charles
AU - Yarger, Jeffery
N1 - Funding Information:
This research was primarily supported by the Army Research Office under Grant W911NF-11-1-0263. We thank Dr. Brian Cherry and Prof. Gregory Holland for help with NMR instrumentation and scientific discussion. J.L.Y. acknowledges support from the National Science Foundation (Grants CHE-1011937 and DMR-1264801) and the Department of Defense (DOD) Air Force Office of Scientific Research (AFOSR) under Award FA9550-14-1-0014.
Publisher Copyright:
© 2016 American Chemical Society.
PY - 2016/5/12
Y1 - 2016/5/12
N2 - The ionicity and transport properties of a series of diethylmethylamine (DEMA) based protic ionic liquids (PILs) were characterized, principally utilizing nuclear magnetic resonance (NMR) spectroscopy. PILs were formed via the protonation of DEMA by an array of acids spanning a large range of acidities. A correlation between the 1H chemical shift of the exchangeable proton and the acidity of the acid used for the synthesis of the PIL was observed. The gas phase proton affinity of the acid was found to be a better predictor of the extent of proton transfer than the commonly used aqueous δpKa. Pulsed field gradient (PFG) NMR was used to determine the diffusivity of the exchangeable proton in a subset of the PILs. The exchangeable proton diffuses with the acid if the PIL is synthesized with a weak acid, and with the base if a strong acid is used. The ionicity of the PILs was characterized using the Walden analysis and by comparing to the ideal Nernst-Einstein conductivity predicted from the 1H PFG-NMR results.
AB - The ionicity and transport properties of a series of diethylmethylamine (DEMA) based protic ionic liquids (PILs) were characterized, principally utilizing nuclear magnetic resonance (NMR) spectroscopy. PILs were formed via the protonation of DEMA by an array of acids spanning a large range of acidities. A correlation between the 1H chemical shift of the exchangeable proton and the acidity of the acid used for the synthesis of the PIL was observed. The gas phase proton affinity of the acid was found to be a better predictor of the extent of proton transfer than the commonly used aqueous δpKa. Pulsed field gradient (PFG) NMR was used to determine the diffusivity of the exchangeable proton in a subset of the PILs. The exchangeable proton diffuses with the acid if the PIL is synthesized with a weak acid, and with the base if a strong acid is used. The ionicity of the PILs was characterized using the Walden analysis and by comparing to the ideal Nernst-Einstein conductivity predicted from the 1H PFG-NMR results.
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U2 - 10.1021/acs.jpcb.6b01203
DO - 10.1021/acs.jpcb.6b01203
M3 - Article
AN - SCOPUS:84969512836
SN - 1520-6106
VL - 120
SP - 4279
EP - 4285
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
IS - 18
ER -