In a recent publication, Daniel Walters, Xian Powers and others in the Balch/Olmstead group have prepared a novel, photoluminescent molecular cage that is entirely constructed from non-luminescent components. In its crystalline form, the resulting molecular "box" suspends an anionic guest, a chloride ion, inside. Crystals of the box change when subject to mechanical force, which causes their rearrangement into an isomeric helicate dimer that uses the original guest as a bridge between two trinuclear components. This transformation is reversible through recrystallization with the appropriate solvents. Each of these forms is highly luminescent, allowing for easy differentiation of the forms and giving promise to the future of host-guest sensors and transport molecules.
More information at https://pubs.acs.org/doi/10.1021/jacs.8b01666