Sensitive and Selective "Turn-On" Chemodosimetric Probes for Fe Based on a Skeleton of 2-Hydroxy-1-Naphthaldehyde.

A naked-eye colored chemodosimeteric probes 4a-f, based on Schiff-azo dye conjugates were synthesized and characterized. All compounds 4a-f exhibited excellent selectivity and high sensitivity in absorbance toward detection of Fe in alcoholic solutions under neutral pH conditions. The detection limit of the probe was shown to be up to 0.05 ppm. A simple paper test strip system for the rapid monitoring of Fe was developed, indicating their convenient use in environmental samples. Electrochemical analysis of metal free conjugates and iron chelated probes confirmed the chelation of ligands. Graphical Abstract.