A density functional investigation of 1,3-bis(4-nitrophenyl)urea as anion receptor

The B3LYP/6-311+G(d,p) optimized structures of 1,3-bis(4-nitrophenyl)urea receptor (1) and its complexes with halide ions F−, Cl−, Br−, oxygen-containing anions NO2-, NO3-, HCO3-, HSO4-, H2PO4-, CH3COO− and C6H5COO− ions were obtained. Binding energies and thermodynamic properties of binding between the receptor 1 and these anions were determined. Binding energies of receptor 1 are in decreasing orders: CH3COO− > HCO3− ∼ C6H5COO− > NO2- > H2PO4- > NO3- > HSO4- for oxygen-containing anions and F− > Cl− > Br− for halide ions. It was found that the binding energies depend on their hydrogen-bond distances of their binding atoms. It was also found that the complexes of receptor 1 and the studied anions are formed via two-point hydrogen-bonding interactions.