Discriminating detection of multiple analytes (F− and CN−) by a single probe through colorimetric and fluorescent dual channels

Abstract

Two novel Schiff base type receptors containing phenol hydroxyl group (1) or methoxy group (2) were designed and synthesized. The receptor 1 with phenol hydroxyl group exhibited different colorimetric and fluorimetric responses to fluoride and cyanide ions. In the colorimetric channel, the colorless solution turned to yellow towards F−, but red in the presence of CN−. In the fluorimetric channel, the nonluminous solution showed different “turn-on” response to F− and CN−, respectively. The distinguishing responses of receptor 1 to the two anions in dual channels were attributed to the disparate interaction mechanisms. F− was detected through the formation of hydrogen bonds and the subsequent deprotonation process. CN− initially formed hydrogen bonds and then it attacked the receptor via a nucleophilic addition reaction. In contrast, the receptor 2 with methoxy group only showed remarkable color change from colorless to yellow towards F−. These results proved that the phenol hydroxyl group played an important role in the discriminating detection of F− and CN−.