Boosting Luminescence of Planar-Fluorophore-Tagged Metal-Organic Cages Via Weak Supramolecular Interactions.

A variety of planar organic fluorophores (R=phenyl, naphthalenyl, pyrenyl) and luminescence promotors (X=Cl, Br, I) were equipped, respectively, on the alternatively arranged vertices of cubic ZnII -imidazolate cages through orthogonal subcomponent self-assembly. It was found that supramolecular interactions, especially weak C-H⋅⋅⋅X interactions, play a key role in activating an efficient radiative pathway, coupled with reduced nonradiative decay rate through metal coordination, therefore significantly boosting the emission quantum yields of the system. This finding provides a strategy that utilizes molecular geometry and supramolecular interactions to modulate the emission efficiency of luminescent cage-based materials.