Abstract: Fluoride measurements are receiving continuous attention from sensor research communities due to the clinical importance of fluoride levels in biological systems and drinking water. We report the synthesis of eight 1,5-diaryl-3-(2-hydroxyl-4,6-dimethoxylphenyl)-2-pyrazolines(4a—4h) and the studies of them as fluorescent sensors for fluoride ion. The structures of all the products were determined by IR, 1H NMR, MS and elemental analysis. Their UV and fluorescence spectra were measured. The influences of four halide ions on their fluorescence properties were studied. Upon addition of other anions such as Cl-, Br- and I-, no significant changes in the fluorescence spectra were observed. However, under identical conditions, the studies show that compounds 4a, 4c, 4d and 4h had evident fluorescence enhancement with F-.The addition of fluoride ion to compound 4d in DMSO led to a red shift(443—453 nm) and to compound 4h led to a red shift(423—433 nm). So we have developed two new fluorescent sensors(4a and 4c). Both of them show high sensitivity and selectivity toward fluoride ion in DMSO.

Key words: 1,5-Diaryl-3-(2-hydroxy-4,6-dimethoxyphenyl)-2-pyrazoline, Fluoride ion, Fluorescence probe