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. (Chemical Equation Presented).