A charge transfer salt consisted of bis(maleonitriledithiolato)zincate dianion and 1,1ʹ-didecyl-4,4ʹ-bipyridinium exhibiting uncommon nematic mesophase behavior

An ionic metal–dithiolene complex, 1,1ʹ-didecyl-4,4ʹ-bipyridinium bis(maleonitriledithiolato)zincate(II) ([Zn(mnt)2]2−), was synthesized and characterized by elemental analysis, infrared spectroscopy and crystal structure. In the [Zn(mnt)2]2− moiety, the complex shows distorted tetrahedral geometry with Zn2+ coordinated to four S-atoms from two mnt2− ligands, and its long molecular axis adopts a similar orientation with 1,1ʹ-didecyl-4,4ʹ-bipyridinium. Two distinguishable redox processes occur in the voltage region of − 1.0 to 1.0 V, with the irreversible and reversible redox couples corresponding to [Zn(mnt)2]2−/[Zn(mnt)2]radical dot− and 1,1ʹ-didecyl-4,4ʹ-bipyridiniumradical dot+/1,1ʹ-didecyl-4,4ʹ-bipyridinium2+, respectively. An uncommon nematic mesophase behavior in this complex was confirmed by polarized-light optical microscopy (POM) and differential scanning calorimetry (DSC) measurements.