Synthesis of benzimidazolium-urea receptors and their anion recognition properties

Due to the fundamental roles that anions play in a wide range of chemical and biological processes, numerous efforts have been devoted to the design of receptors capable of selectively binding and sensing anions. Herein, three benzimidazolium-urea receptors were designed and synthesized. The interaction between these receptors and various anions(F ^-, Cl ^-, Br ^-, I ^-, CH ₃COO ^-, HSO ₄ ^-, H ₂PO ₄ ^-) were studied by UV-Vis spectrum, fluorescence spectrum and ¹H NMR. The results demonstrate that the receptors and anions form 1:1 complex, and the receptors display a strong (C-H) ⁺⋯X ^-, N-H⋯X hydrogen bonds and charge-charge interactions in anion recognition.