A colorimetric and fluorescence sensor based on biphenolic-dansyl derivative for specific fluoride ion detection

2MODIFIER LETTER PRIME-(2-((4-(methylthio)phenyl)amino)-2-oxoethoxy)-[1,1MODIFIER LETTER PRIME-biphenyl]-2-yl 5(dimethyl amino)naphthalene-1-sulphonate (1) was synthesised and used as a F- ion sensor. The selectivity of sensor 1 with various anions (F-, Cl-, Br-, CH3COO-, C6H5COO- and H2PO4-) in DMSO was evaluated by H-1 NMR, UV-visible and fluorescence study. For H-1 NMR, an amide proton of sensor 1 disappeared due to the deprotonation reaction upon addition of F- ion. On the contrary, the proton signal of HF2- emerged at 16.11 ppm. Upon addition of F- ion, sensor 1 showed a new absorption band at 300 nm and the solution turned colourless. For fluorescence response, sensor 1 exhibited the enhancement of emission intensity at 434 nm with slight blue shift when titrated with F- ion. These results suggest that sensor 1 possessed high sensitivity and selectivity towards F- ion detection. In addition, the sensor 1 test strip coated on TLC plates and filter papers were demonstrated for specific detection F- ion.