Cholic Acid Based Anion Receptor Containing NHCarbamosulfonamide Binding Units.

Abstract

A synthetic receptor (S2L) based on cholic acid and possessing two NH – carbamosulfonamide binding sites at C7 and C12 positions was designed and synthesized. The binding abilities toward various anions (F^-, Cl^-, Br^-, I^-, AcO^-, BzO^-, CN^-, H₂PO₄^-, HSO₄^-, ClO₄^- and NO₃^-) were investigated using ¹H-NMR spectroscopy, UV-Vis spectrophotometry, and computer simulations. Changes in the ¹H-NMR spectra revealed the binding with anions occurring at the NH - carbamosulfonamide binding sites via a hydrogen bonding formation. Results from UV-Vis spectra, and optimized structures of the S2L-halide anion complexes exhibited a possibility to deprotonation at one of the NH-carbamolsulfonamide group in the case of the binding with strong basic anions (CN^-, F^-, AcO^-, BzO^- and H₂PO₄^-). Job plot analysis indicated the formation of 1:1 host - guest complexation. The highest binding constant was obtained from CN^- anion (log K = 6.08).