Synthesis of anion receptors based on aroylthiourea and their anion recognition

Three new aroylthiourea receptors were synthesized. The binding properties of the receptors with anions such as F-, Cl-, Br-, AcO-, HSO4- and H2PO4- were examined by UV-Vis spectroscopy methods. The results showed that hydrogen-bonding complexes were formed between receptors and anions. The color was changed from colorless to yellow upon addition of F and AcO- to the solution of the three receptors, which was perceptible to recognition by naked eye. However, no obvious color changes were observed on addition of the other anions. The results indicated that a 1 : 1 stoichiometry complex was formed between compounds and anions, while H-1 NMR titrations and solvate effect confirmed hydrogen-bonding interaction between the receptors and anions.