Synthesis and anion binding properties of a urea-based molecular cleft

Abstract A new urea-based molecular cleft ( L ) derived from propylene-linked dipodal amine has been synthesized and its binding affinities for anions have been investigated by 1 H NMR and UV–vis spectroscopic titrations in DMSO. The receptor has been shown to bind F − , HSO 4 − , H 2 PO 4 − , and AcO − in a 1:1 binding mode via hydrogen bonding interactions, providing the highest binding constant for F − . In addition, the new cleft shows a naked-eye color change in the presence of F − in DMSO. The interactions of L with fluoride have also been evaluated by theoretical calculations based on density functional theory (DFT), revealing that the cleft encapsulates a fluoride via four NH⋯F − and two CH⋯F − bonds.