Linker-length dependence of the reorientational dynamics and viscosity of bis(imidazolium)-based ionic liquids incorporating bis(trifluoromethanesulfonyl)amide anions

► Bis(imidazolium)-based dicationic ionic liquids. ► The ionic liquids were characterised with respect to viscosity and dynamics. ► A linker-length dependence of viscosities was related to the reorientational motion. ► We found the boundary in the linker length where the dominant interactions change.