Two new chemosensors for fluoride ion based on perylene tetra-(alkoxycarbonyl) derivatives

Two novel fluorescence sensors (1 and 2) based on perylene tetra-(alkoxycarbonyl) derivative (PTAC) were designed and synthesized. The properties of sensors were detected by absorption, fluorescence spectra and electrochemical response. Test results indicated that the sensors had specific selectivity and high sensitivity for fluoride ion (F−) among the halide anions examined (F−, Cl−, Br− and I−). The absorption and fluorescence emission properties of the sensors arise from the intermolecular proton transfer (IPT) process between a hydrogen atom on the amide N position of sensor and the fluoride ion. Corresponding orbital electron distribution and molecular geometry configurations of the compounds were predicted by density functional theory (DFT). Moreover, sensor-based test strips can conveniently detect F− without any additional equipment. Incorporating S atom into perylene tetra esters 2 led to modified aromatic systems while retaining planarity and large conjugated π-bonds, and such molecular tailoring approach would be helpful for designing and synthesizing novel ratio metric fluorescent perylene chemosensors for F−.