Fluoride anion recognition by a multifunctional urea derivative: An experimental and theoretical study

In this work we demonstrate the ability of a multifaceted N,N-disubstituted urea to selectively recognize fluoride anion (F) among other halides. This additional function is now added to its already reported organocatalytic and organogelator properties. The signaling mechanism relies on the formation of a charge-transfer (CT) complex between the urea-based sensor and F in the ground state with a high association constant as demonstrated by absorption and fluorescence spectroscopy. The nature of the hydrogen bonding interaction between the sensor and F was established by 1H-NMR studies and theoretical calculations. Moreover, the recovery of the sensor was achieved by addition of methanol. © 2016 by the authors; licensee MDPI, Basel, Switzerland