Physical and Electrochemical Modulation of Polyoxometalate Ionic Liquids via Organic Functionalization

The synthesis and characterization of two new organic/inorganic hybrid polyoxometalate ionic liquids (POM-ILs) is described. The POM-ILs were formed by pairing bulky trihexyl(tetradecyl)phosphonium cations [THTP](+) with organosiloxane and organophosphonate-functionalized Keggin-type POMs [PW11O39(SiPh)(2)O](3-) and [PW11O39{P(O)Ph}(2)](3-). The functionalized POM-ILs were found to be more thermally stable than their molecular precursors and comparison of their electrochemical properties showed that the tunable electronic structures of the POM anions determined the redox chemistry of the hybrid materials.