Enhancing Solid-State Conductivity through Acid or Base Doping of Protic Imidazolium and Imidazolinium Triflate Salts

Alison Chong, Haijin Zhu, Kate Nairn, Maria Forsyth, Douglas Macfarlane

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9 Citations (Scopus)


Protic salts, including those showing plastic crystal behavior, are an interesting family of materials being rediscovered for use as solid conducting materials. This work compares two such compounds, 2-methylimidazolium triflate, [2-MeHIm][TfO], and 2-methylimidazolinium triflate, [2-MeHImn][TfO]. This subtle change in structure resulted in substantial differences in thermal behavior; [2-MeHIm][TfO] shows two solid-solid phase transitions while none were observed for [2-MeHImn][TfO]. However, both compounds are in a disordered solid state (ΔSf < 40 JK-1 mol-1) resulting in relatively high room temperature conductivities. Neat [2-MeHImn][TfO] had a conductivity above 10-5 S cm-1, but the addition of either the component acid or base as dopants resulted in a substantial increase in conductivity, to over 10-4 S cm-1 at 30 °C. Solid-state 1H and 19F NMR studies suggest that the dopants enhance the conduction primarily by increasing the proportion of mobile ions in the solid matrix. However, [2-MeHIm][TfO] also displays evidence of proton hopping via the cation.

Original languageEnglish
Pages (from-to)27849-27859
Number of pages11
JournalJournal of Physical Chemistry C
Issue number50
Publication statusPublished - 21 Dec 2017

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