Design of Dication-Type Amino Acid Ionic Liquids and Their Application to Self-Assembly Media of Amphiphiles

Abstract Dication-type amino acid ionic liquids have been prepared and their physicochemical properties, such as viscosity, glass transition temperature, Kamlet-Taft parameter, ionic conductivity, and refractive index, have been examined. Comparing these properties of the dication-type amino acid ionic liquids with those of corresponding monocation-type ones, we have investigated the effects of the cation-bridging. In addition, the comparison of aliphatic amino acid ionic liquids and aromatic ones has been also examined. By examining lyotropic liquid-crystalline behavior of an amphiphile in these ionic liquids, we have examined how these modifications of ionic liquids make changes in the potential utility of ionic liquids as self-organization media of amphiphiles. It has been found that critical concentrations of lyotropic liquid-crystalline amphiphiles in ionic liquids are successfully reduced by bridging their cations with covalent bonding and/or introducing aromatic-structures into their anions.