Hetero-Bambusurils

Synthetic anion carriers are essential for studying natural ion transporters and channels and for useful applications, such as treatment of channelopathies, supramolecular architecture, anion sensing and catalysis. Driven by the hypothesis that replacement of oxygen atoms in bambusurils (BUs) by other heteroatoms could significantly modify their anion binding properties, we calculated their molecular electrostatic potential and found a general trend of anion-affinity: S>O>NH. We confirmed these predictions experimentally by synthesizing semithio- and semiaza-BUs and studying their binding and transport properties. Although all analogs are excellent anion binders, only semithio-bambus[6]uril is an effective transmembrane transporter capable of polarizing lipid membranes through selective anion uniport. Semiaza-BUs exhibit simultaneous accommodation of three anions, linearly positioned along the main symmetry axis, which is reminiscent of natural chloride channels in E. coli.