Pyridine-Triggered Fluorescent Switching in Coordination-Induced Allosteric Crystal Transformation

Two zinc complexes with stimuli-responsive properties have been realized in [Zn­(L)2] (1) and [Zn­(L)2(py)]·py (2) (HL = N-(2-hydroxybenzylideneamino)-1,8-naphthalimide, py = pyridine). The crystal-to-crystal transformation between 1 and 2 is achieved by coordination/decoordination of pyridine, leading to an allosteric effect of the naphthalimide fluorophore. Thus, this pyridine-mediated twisted π-conjugated nature of the ligand between 1 and 2 is responsible for the selective and reversible fluorescent switching, which offers a profound insight into the fascinating field of solid-state stimuli-responsive luminescence materials and promotes the development of novel materials.