Fluorescent dialdehyde-BODIPY chitosan hydrogel and its highly sensing ability to Cu2+ ion

Fluorescent hydrogel with proper hydrophilicity and thermal stability , excellent sensitivity and high selectivity has important practical and scientific significance, especially in heavy metal ion detection. In this work, by adjusting the content of [2, 6-Bis-[4-formylthiophene]]-1,3,5,7-tetramethyl-8-phenyl-4, 4-difluoroborazaindoloene (B3), as a cross-linking agent, a series of chitosan- fluoroboron dipyrrole-chitosan-based fluorescent hydrogels (CBC) with large stokes shift were designed and prepared. The hydrogels can be used as fluorescent probes for identifying Cu 2+ in aqueous solution. The linear quenching range of Cu 2+ is 0–50 μM, and the detection limit and quenching constant are 4.75 μM and 3.52 × 10 4  M −1 , respectively. Under the interaction of Cu 2+ , the imine bond C N was converted to C- N bond, which causes the phenomenon of fluorescence quenching . In addition, relatively high crosslink density improves hydrophilicity and thermal stability of initial chitosan, and made the swelling ability better.