New Ionic Liquid Crystal of N,N'-Dialkylbenzimidazolium Salt Comprising Cobalt (II) Thiocyanate

A new metal-containing ionic liquid crystal of N,N ′- dialkylbenzimidazolium of [(C12H25)2-bim]2[Co(SCN)4] (bim = benzimidazole) was synthesized by reaction of the ligand [(C12H25)2-bim]Br and cobalt (II) thiocyanate. Its structure was characterized by X-ray crystallography, IR spectroscopy, and elemental analysis. The cation of the title complex adopts a U-shaped conformation and is packed in a highly interdigitated bilayer fashion. The distorted tetrahedron [Co(SCN)4]2– is located between the cationic bilayers individually. The liquid crystalline behavior of the title complex was studied by differential scanning calorimetry and polarized optical microscopy. The results of the ionic conductivity measurement displayed that the ionic conductivity of the title complex was significantly higher than that of the ligand. The conductivity of the title complex had very large difference in the different organic solvents, while that had a maximum value in N,N ′-dimethylformamide solution.