Low-melting, Low-viscous, Hydrophobic Ionic Liquids: N-Alkyl(alkyl ether)-Nmethylpyrrolidinium Perfluoroethyltrifluoroborate

A series of new hydrophobic ionic liquids comprising N-alkyl(alkyl ether)-N-methylpyrrolidinium and perfluoroethyltrifluoroborate were prepared and characterized. The new [C2F5BF3]- -based salts show lower melting points than the corresponding [BF4]- -based ones. Of these new salts, five are liquids at room temperature and show very low viscosities (37–71 cP at 25 °C), high ionic conductivities (3.0–6.8 mScm^-1) and wide electrochemical windows.