Rhodanine-based fluorometric sequential monitoring of silver (I) and iodide ions: Experiment, DFT calculation and multifarious applications

A simple rhodanine derived fluorophoric unit has been designed for selective detection of Ag+ and I- ions in DMSO-H2O medium. The sensor R1 showed an obvious “turn-on” fluorescence response toward Ag+ due to the inhibition of both C-N single bond free rotation, internal charge transfer (ICT) and the formation of chelation enhanced fluorescence (CHEF) effects. The fluorescence quantum yield (Φ) was increased from 0.0013 to 0.032 for receptor R1 upon the Ag+-complexation. In addition, the 1:1 complexing stoichiometry was employed based on Job’s plot analysis with detection limit of 24.23 × 10−7 M. Conversely, receptor R1+Ag+ particularly detects I- ion over other co-existing anions by the “turn-off” fluorescence response due to the formation of AgI, displacing the receptor R1 with the quantum yield of 0.0014. The detection limit was calculated to be 22.83 × 10−7 M. The sensing behaviour of receptor R1 toward Ag+ was also supported by density functional theory (DFT) calculations. Moreover, the sensing ability of reported receptor R1 could be exercised in multifarious applications like paper strip, silica-supported analysis, staining test for latent finger print, logical behaviour, smartphone-assisted quantitative detection and real water samples studies. [Display omitted] •A simple rhodanine derived fluorescent receptor (R1) displays consecutive recognition of silver (I) and iodide ions.•The combined ICT-CHEF mechanism is proposed for a specific recognition of Ag+ ions at the physiological pH range.•The quantum yield (Φ) of receptor R1 was increased upon the binding of Ag+ from 0.0013 to 0.032.•Naked-eye detection, LFP visualization and molecular based logic gate applications were studied for the receptor R1.•Furthermore, the receptor R1 could be used for on-the-spot smartphone-assisted detection.