New chloride anion receptors: trifluoromethyl sulfonylated polyamines

A new chloride anion receptor, derivatized oligoethylene oxide CF3SO2 substituted tetraamine (3), was synthesized. This compound exhibited strong Cl-1 ion binding properties in nonpolar solvents such as benzene. Neutral red and Nile blue chloride dye molecules do not dissolve in benzene. However, when compound (3) was added to a benzene solution containing the solid dye compounds, the color of the solution immediately turned to dark blue, and the intensity of the color proportionally increased with the concentration of (3). The phenomena indicated that the Cl- ions of Neutral red or Nile blue chloride are complexed with (3), thereby resulting in an increase in the solubility of the Neutral red or Nile blue cations in benzene. The dissociation of chloride anions from 4,4',4''-trimethoxytriphenyl chloromethane in a benzene solution proceeded with addition of compound (3) and increased with increasing time at room temperature. In contrast, another tetraamine compound (4) which was substituted with a less electron withdrawing group, CH3SO2, did not complex with Cl- anions in a benzene solution.Key words: Cl- anion receptor, trifluoromethyl sulfonated tetraamine, ion pair dissociation. </jats:p