Water-Soluble Pillar[5]arenes: Synthesis and Characterization of the Inclusion Complexes with p-Toluenesulfonic Acid

Novel symmetric cationic water-soluble pillar[5]arenes bearing trimethylammonium/methyldiethylammonium groups at both of two rims were synthesized by step-by-step functionalization of the perhydroxylated pillar[5]arene. The recognition ability of water-soluble pillar[5]arenes toward p-toluenesulfoacid was studied. The information on binding mode of the guest inclusion was studied by H-1 and 2D NMR spectroscopy. The interaction of synthesized pillar[5]arenes with the substrate and the formation of the 1:1 complexes was shown by UV spectroscopy.