Among the range of biologically important anions, fluoride is of particular interest owing to its established role in preventing dental caries. The fluoride ion has also been examined extensively as a treatment for osteoporosis. In pursuit of fluorescent fluoride ion a naphthalene urea derivative 1 was synthesized and its fluorescent spectral characteristics with fluoride ions was investigated. Two new naphthalene urea derivatives 2, 3 that were selective ‘naked-eye’ fluoride ion sensors were synthesized by introducing a nitro group and their anion binding properties were investigated by UV-vis spectroscopy and color changes. For the application of fluoride chemosensors, fluoride detection will be tested for nucleophilic substitution between aryl alkoxide and aryl fluoride in various synthetic reactions.