Coordination Polymerization-Induced Emission Based on a Salicylaldehyde Hydrazone AIEgen toward Zn2+ Detection

An AIEgen chemosensor of H2hbih, [(E)-N-(2-hydroxybenzylidene) isonicotinohydrazide], containing an isonicotinic moiety condensated by salicylaldehyde was prepared and characterized. It can detect Zn2+ ions selectively in the “off-on” mode based on the coordination polymerization-induced emission (CPIE), with the limit of detection (LOD) being 2.8 × 10–7 M. The corresponding two-dimensional (2D) coordination polymer of the Zn2+ complex (1) was synthesized to investigate the response mechanism. Powder X-ray diffraction and single-crystal X-ray diffraction proved that complex 1 is the species formed in the detection system. Sensing of Zn2+ cannot be interfered by Cd2+, as confirmed by the molecular Cd2+ complex (2) without the CPIE mechanism. H2hbih can be successfully applied to bioimaging of Zn2+ monitoring in mung beans, larval zebrafish, and inner epidermis cells, which sheds light on a new strategy for designing AIE-based chemosensors via polymerization-induced self-assembly.