Damming a Molecular Energy Reservoir: Ion-regulated Electronic Energy Shuttling in a [2]Rotaxane

Bidirectional electronic energy shuttling is shown to occur between the molecular ring and axle components of a rotaxane. The engineered energetic and kinetic parameters give rise to long-lived, delayed luminescence. Perturbation of the quasi-isoenergetic ring and stopper chromophore excited-state energy levels upon cation binding influences the energy shuttling process, and hence luminescence read-out, representing a new potential mechanism in luminescent molecular chemosensor development