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

Abstract

In this work we demonstrate the ability of a multifaceted N,Nʹ-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.