Among ionic liquids, phosphonium-based ionic liquids (PILs) are quite elegant. This category of ionic liquids represents some merits such as higher thermal and chemical stability compare with other types of ionic liquids. These influential characteristics of PILs, make them as potential materials for various kinds of applications in the laboratory and industrial processes. They can be applied as elegant catalyst and/or solvent for organic functional group interconversion. Also, the diffusivities of gases such as carbon dioxide, in the PILs are much higher than imidazolium-based ionic liquids. PILs have numbers of unique applications in electrochemical systems. PILs are an unprecedented class of electrolytes that can support the electrochemical generation of a stable superoxide ion, unlike of organic solvents. There is also a growing interest for their use in separation processes including metal ions extraction, extractive desulfurization, gas adsorption and dissolution or extraction of biologically relevant compounds. Also, experimental works have also satisfied that the PILs fulfil the necessary requirement of being a good inhibitor of metal corrosion under different media because of their surface active properties. Owning to special physicochemical properties, the PILs are emerging as possible candidates to improve surfactant enhanced oil recovery methods [1-3]. This work will present an excellent puzzle that each of its pieces leads to the rational design, synthesis, and applications of the novel and tasked-specific PILs as multi-purpose materials.
