Because of existence of abundant hydroxyl groups, both of hydroxyly-3-methylimidazolium cation based ionic liquids and deep eutectic solvent can react with the Ni(II) complexes showing thermochromism. This novel thermochromic system can be driven by the solar heat, and are sensible and environmentally friendly. The ILs-Ni(II)-complex-PVDF composite films are thermochromic with different nickel complexes. Cryo-solvatochromism in response to cooling from room temperature to well below 0℃ can be achieved in a 1-hydroxylalkyl-3-methylimidazolium cation based ionic liquid, containing a Ni(II) complex and excess 1-butyl-3-methylimidazolium chloride. This review presents the recent fundamental and application work on a number of thermochromic and cryochromic systems based on Ni(II) complex and Ionic liquids, including the 1-hydroxylalkyl-3-methylimidazolium cation based ionic liquids and deep eutectic solvent.

thermochromism  /  cryochromism  /  nickle (II) complexes  /  ionic liquids  /  composite films