A dipodal bis-urea receptor has been synthesized from the reaction of 8-amino quinoline and 1,4-phenylene diisocyanate in dichloromethane, and the anion binding ability of the receptor has been studied using fluoride, chloride, bromide, iodide, perchlorate, nitrate, dihydrogen phosphate and hydrogen sulfate by UV-Vis titrations in DMSO. The results show that the receptor binds each of the anions with a 1:1 stoichiometry, showing high affinity, and moderate selectivity for hydrogen sulfate among the anions studied. Ab initio calculations based on density functional theory (DFT) suggest that an anion (X−) is bonded within the cleft formed by the two arms of the receptor through two NH…X− and two aromatic CH…X− interactions. The results from solution and theoretical studies suggest that binding is predominately influenced by hydrogen bonding interactions and the basicity of anions.

The title compound, C33H26N6O2, contains two 3-(quinolin-8-yl)urea groups linked to a diphenyl­methane. The asymmetric unit contains two mol­ecules, A and B. Each quinoline plane is essentially parallel to the attached urea unit [dihedral angles = 8.97 (18) and 8.81 (19) in molecule A and 18.47 (18) and 4.09 (19)° in molecule B]. The two benzene rings are twisted, making dihedral angles of 81.36 (8)° in A and 87.20 (9)° in B. The molecular structures are stabilized by intramolecular N—H⋯N hydrogen bonds. In the crystal, each urea O atom is involved in two N—H⋯O hydrogen bonds, generating two inter­penetrating three-dimensional sets of mol­ecules.