“Water-like” Dual-Functionalized Ionic Liquids for Enzyme Activation

[Image: see text] By mimicking the water structure to improve the enzyme activity, we designed imidazolium (Im)-based ionic liquids (ILs) functionalized with both ether and tert-alcohol groups (e.g., [CH(3)(OCH(2)CH(2))(n)-Im-t-BuOH][Tf(2)N]). This unique combination of the “water-like” structure enabled very high transesterification (synthetic) activities for immobilized lipase B from Candida antarctica, which are up to 2–4 folds higher than nonfunctionalized “classical” ionic liquids (such as [BMIM][Tf(2)N]) and up to 40–100% higher than diisopropyl ether and tert-butanol. Fluorescence emission spectra confirmed the general protein structural preservation in these tailored ionic solvents. In addition, functionalized ILs showed high thermal stabilities, which are comparable with diisopropyl ether but much higher than tert-butanol.