In the last decade, ionic liquids (ILs) have attracted significant scientific interest as “designer liquids” with tunable physicochemical
properties [1–3]. In the catalysis field, the task specific ILs have
been widely studied due to their high catalytic activities and good
recyclabilities [4–6]. Along this line, a family of organic–inorganic
hybrids was synthesized with the combination of polyoxometalates
(POMs) and ILs (POM–ILs). These interesting organic–inorganic hybrid materials have properties of both POM anion and IL cation.
They were used as acid catalysts in various organic reactions [7–9].