A facile synthesis of amide-based receptors under microwave conditions: investigation of their anion recognition properties by experimental and computational tools

Two novel amide-based receptors were synthesized under microwave irradiation. Their chemical structures were confirmed by IR, H-1 NMR, C-13 NMR, and elemental analysis. The binding properties of these amide-based receptors to various anions (H2PO4-, HSO4-, C6H5CO2-, CH3CO2-, ClO4-, F-, Cl-, and Br-) were examined by UV titration in THF at 20 degrees C. The results indicated that the receptors form 1: 1 complexes with anions and they have the strongest affinity for fluoride (F-) among the anions considered. Molecular dynamics calculations by AMBER and quantum mechanical calculations performed at the B3LYP and M062X levels of theory using the 6-31 + g(d,p) basis set provided models for the complexation mode between the receptors and anions and yielded binding energies for the complexes.