Thiourea Based Tweezer Anion Receptors for Selective Sensing of Fluoride Ions

Three 3,3′‐di(4‐substituted‐phenyl)‐1,1′‐isophthaloylbis(thiourea) compounds were designed as novel neutral anion receptors, and synthesized by simple steps in good yields. The single crystal structure of receptor 1 shows that a solvent molecule was captured by the host molecule through intermolecular hydrogen bonding. Moreover, it was self‐assembled as a supramolecular system for the presence of abundant inter‐ and intramolecular hydrogen bonding and π‐π interactions between phenyl groups. Their application as anion receptors has been examined by UV‐Vis and 1 H NMR spectroscopy, showing that they had a higher selectivity for fluoride than other halides. The host and guest formed a 1:1 stoichiometry complex through hydrogen bonding interactions in the first step, then following a process of deprotonation in presence of an excess of F − in the solvent of DMF.