A new fluoride ion colorimetric sensor based on dipyrrolemethanes

Colorimetric fluoride ion sensors were developed using dipyrrolemethanes 1–4 synthesized from the reaction of aldehydes and pyrrole. The sensors showed a color change upon addition of fluoride ion with a substantial bathochromic shift. No significant color change was observed upon addition of any other anions. The significant changes of absorption bands and color show that chemosensor is selective toward fluoride ion over other anions such as Br−, Cl−, NO3−, HSO4−, SO42−, AcO− and H2PO4−. The binding constants of sensors with fluoride ion were obtained in the order of ∼102 which is enough to detect the fluoride ion.