Rapid, Sensitive, and Selective "ON-OFF" Detection of Fe3+ Ions Using Novel Acetalophanes and Their Applications in Real Samples

Three novel acetalophanes 1a-c have been designed, synthesized and characterized. The receptors 1b-c , featuring bulky anthracene groups, displayed significant selectivity for Fe 3+ ions, resulting in a turn-off fluorescence mode in a DMF-buffer solution. Conversely, the non-steric probe 1a could serve as a versatile sensor for the simultaneous detection of Fe 3+ and Cu 2+ ions in MeOH-buffer solution. The sensing mechanism for the capability of 1a was demonstrated to be different, as evidenced by the addition of cyanide ions. The probes with Fe 3+ exhibited a sensing mechanism that resulted in the deprotection of acetals to the corresponding starting materials, as confirmed by 1 H NMR, IR spectra and TLC analysis. The attractive features of these practical and efficient sensors are selectivity, sensitivity (limit of detection = 0.15 µM by 1a , 0.16 µM by 1b and 0.14 µM by 1c ), rapid response (less than 5 seconds). The on-site monitoring of various real samples, including well water, apricot, and green tea, proved to be successful for the quantitative and cost-effective detection of Fe 3+ . The method demonstrated good precision, even in the presence of other interfering materials.