A high selective anion colorimetric sensor based on salicylaldehyde for fluoride in aqueous media

A new and simple salicylaldehyde-based sensor 1 designed for fluoride sensing has been investigated in DMSO and even in the 9/1 DMSO/H2O (v/v) mixtures. The affinity constants of receptor 1 for anionic species in the 9/1 DMSO/H2O (v/v) reveal that it is sensitive to F. Also, the color changes induced by anions can provide a way of detection by ‘naked-eye’. These result can be substantiated by the spectrum changes upon the addition of 25 equiv. anions to 1 in the 9/1 DMSO/H2O solution. The further insights to the nature of interactions between the sensor 1 and F− were investigated by 1H NMR titration experiments in 9/1 DMSO-d6/H2O (v/v). In addition, the proposed binding mode between 1 and F− was suggested.