Pyrazinium iodoargentate with versatile photo- and thermo-chromism

A new electron donating-accepting iodoargentate hybrid, [Hpyz]2[Ag2I4]·H2O (1) directed by monoprotonated pyrazinium cation has been constructed under solvothermal reactions. The title compound exhibits versatile photo- and thermochromism due to reversible hydration-dehydration, as well as subsequent occurrence of intermolecular electron-transfer (ET) and changes of intermolecular charge transfer (CT) states, demonstrating suitable match between monoprotonated pyrazinium with moderate electron accepting ability and electron-rich iodoargentate.