This chapter presents the definition, synthesis, and possible application of cyclo and polyphosphazene-based ionic liquids (PzILs). PZILs constitute an alternative class of phosphorus nitrogen compounds and their derivatives have been widely used in biologically-active materials, electrolytes, lubricants, catalysts or nanomaterials. Considerable information is available on substitution reactions taking place at the phosphorus atoms of poly and cyclophosphazenes, thus, a wide variety of phosphazene derivatives have been obtained. However, quaternization of ring nitrogen atoms has received less attention. In addition, phosphazenes containing aliphatic and aromatic substituents with terminal tertiary amino groups are synthesized and subsequently quaternized with methyl iodide. The successive metathesis with salts such as LiN(SO2CF3)2 or NaBF4 gives the respective PzILs. In the compounds identified as protonic ionic liquids (PILs) or protic molten salts (PMOSs), the positively charged position is determined by X-ray diffraction study. PzILs are also soluble in water and in many polar organic solvents.
Part of the book: Recent Advances in Ionic Liquids