Electrochromic Bis(terpyridine)metal Complex Nanosheets

A series of electrochromic metal complex nanosheets comprising 1,3,5-tris­(4-(2,2′:6′,2″-terpyridyl)­phenyl)­benzene or 1,3,5-tris­((2,2′:6′,2″-terpyridyl)­ethynyl)­benzene and Fe2+ or Co2+ was synthesized. The preparation of multilayered nanosheets was achieved by liquid/liquid interfacial synthesis using an organic ligand solution and an aqueous metal–ion solution. The resultant nanosheet had a flat, smooth morphology and was several hundreds of nanometers thick. Upon its deposition on an indium tin oxide (ITO) electrode, the nanosheet underwent a reversible and robust redox reaction (Fe3+/Fe2+ or Co2+/Co+) accompanied by a distinctive color change. Electrochromism was achieved in a solidified device composed of the nanosheet, a pair of ITO electrodes, and a polymer-supported electrolyte. The combination of Fe2+ and Co2+ nanosheets in one devicedeposited on each ITO electrodedemonstrated dual-electrochromic behavior.