Multiple-Stimuli Fluorescent Responsive Metallo-Organic Helicated Cage Arising from Monomer and Excimer Emission

Abstract Effectively controlling monomer and excimer emission in a singular luminous platform is challenging due to their highly stable structures in solution, solid, or doped states when subjected to external stimuli. This study presents a metallo-cage (MTH) featuring a triple helical motif that displays a unique dual emission. This emission arises from both intramolecular monomer and intermolecular excimer, respectively. The distorted molecular conformation of MTH and the staggered stacking mode for MTH excimer were verified through single crystal X-ray diffraction analysis. These structural features facilitate the switch between monomer and excimer emission, which is induced by changes in concentration and temperature. Significantly, adjusting the equilibrium between these two states in MTH enables the production of vibrant white light emission in both solution and solid state. Moreover, when combined with a PMMA (polymethyl methacrylate) solution, the resulting thin films can serve as straightforward fluorescence thermometer and materials for thermally activated information encryption.