Imidazole appended rotatable hydroxy quinoline scaffold as dual signaling fluorescent chemosensor: Detection of silver ions with hypsochromic shift and hydroxide ions with bathochromic shift and their LFP’s, anticounterfeiting, soil analysis and bio-imaging

Abstract

An imidazole conjugated hydroxy quinoline based chemosensor (QBI) was developed for the specific dual detection of silver (Ag+) and hydroxide (OH−) ions by fluorimetric technique. QBI had weak fluorescent emission, upon binding with Ag+ and OH−, fluorescence intensity enhanced with a large hypsochromic shift for Ag+ ion and notable bathochromic shift for OH− ions respectively. Three modes of possible mechanistic pathways accounts for the detection of the Ag+ ions, restriction of the C–C free rotation between the quinoline and imidazole scaffolds, blocking of photoinduced electron transfer (PET) process assisted by the Intramolecular charge transfer (ICT) process. On other hand, the –OH moiety of QBI gets deprotonated during the process of detecting OH− ions. The binding stoichiometry of complexations was confirmed by Jobs plot, Benesi-hildebrand, 1H NMR titration, DFT analysis and ESI-TOF. The limit of detection (LOD) of QBI with Ag+ and OH− was found to be 3.53 × 10−8 M for Ag+ and 1.5 × 10−7 M respectively. Latent fingerprintvisualization (LFP), anti-counterfeiting applications, and soil analysis are merely a few instances of where QBI has been effectively put to use in the real world for the specific detection of Ag+ and OH− ions. Furthermore, receptor QBI was utilized in bacterial imaging against E.coli and pseudomonas pathogens for the detection of both ions.