Pyridinecarbohydrazide-based fluorescent chemosensor for In3+ ions and its applications in water samples, live cells, and zebrafish imaging

Abstract

Herein, we synthesized and characterized a new probe N',N'-bis((E)-2-hydroxy-3-methyl benzylidene)pyridine-2,6-dicarbohydrazide (L) for the detection and quantification of In3+ ions. Probe L exhibits a significant fluorescence ON upon the addition of In3+ in DMSO:H2O (2:8, v/v) media with a detection limit as low as 62.7 nM. The key sensing ability of L towards In3+ was attributed to the chelation-enhanced fluorescence (CHEF). The binding stoichiometry between L and In3+ was found to be 1:2 by Job’s plot, nuclear magnetic resonance (NMR), and mass analysis, with the calculated association constant of (Ka), 1.42 × 103 M−2 by Benesi-Hildebrand (BH) method. Various techniques such as 1H NMR, FTIR, ESI mass, and DFT analysis were used to determine the mechanism by which L binds to the In3+ ions. The detection of In3+ in water samples demonstrates that L might be used to detect In3+ ions in environmental samples. Notably, the bio-imaging revealed that L successfully detected In3+ ions in DrG cells and zebrafish larvae.