Electrochromic 2,5-Dihydroxyterephthalic Acid Linker in Metal-Organic Frameworks

We report electrochromism of M-MOF-74 (M=Mg, Mn, Co or Zn), a honeycomb nano-framework in which hexagonally packed one-dimensionalarrays of metal cations are coordinated with 2,5-Dihydroxyterephthalic acid linker. Raman spectroscopy upon electrochemical doping combined with density functional theory calculations reveals redox reactions of the linker while the metal cations stay divalent asprobed by X-ray photoemission spectroscopy. Excellent adhesion of the MOFs to glass allows synthesis of quality thin films to be implemented into electrochromic devices that exhibit promising colour contrast and durability.