Benzenebistriazole-strapped calix[4]pyrrole: a neutral anion receptor with CH and NH donor groups that exhibits high sulfate binding affinity and selectivity in aqueous solutions.

A calix[4]pyrrole strapped by benzenebistriazole has been prepared as an artificial anion binding receptor. This neutral anion receptor shows high sulfate binding affinity and selectivity in an aqueous solution. In solid state, the receptor binds the sulfate anion in a chair-like 3D cavity via multiple N-H and C-H hydrogen bonds.