A Borromean Weave Coordination Polymer Sustained by Urea−Sulfate Hydrogen Bonding and Its Selective Anion Separation Properties

A 3-fold (2D → 2D) (6,3) Borromean weave coordination polymer sustained by urea−sulfate hydrogen bonding is formed when N,N′-bis(3-pyridyl)-p-phenylenebisurea (L1) is reacted with ZnSO4·7H2O, whereas the corresponding bis-amide derivative N,N′-bis(3-pyridyl)terephthalamide (L2) gave a coordination polymer displaying a 2D corrugated sheet under the identical reaction conditions; sulfate anion can be selectively separated from a complex mixture of anions (sulfate, nitrate, perchlorate, and triflate) by in situ crystallization of these coordination polymers.