Calix[4]arene containing thiourea and coumarin functionality as highly selective fluorescent and colorimetric chemosensor for fluoride ion.

A novel calix[4]arene based chemosensor L which contains coumarin and thiourea group has been synthesized and characterized. Interestingly, probe L exhibits both fluorescent and colorimetric response to fluoride anion with high selectivity and sensitivity. The addition of F- to a solution of probe L resulted in obvious naked-eye color change from colorless to orange under daylight and prominent fluorescence quenching. Further studies showed that the recognition process was less affected by other anions. The binding property of L with F- was studied by a combination of combination of various spectroscopic techniques, such as absorption spectra, fluorescence titration, Job's plot and 1H NMR titration. We are anticipating that this architecture with functional group attached to upper rim of calix[4]arene platform may provide a new approach for the development of F- chemosensor.