A Metal−Organic Framework Functionalized with Free Carboxylic Acid Sites and Its Selective Binding of a Cl(H₂O)₄^- Cluster

A metal−organic framework with one-dimensional channels decorated with −COOH binding sites was synthesized under aqueous acidic conditions, which inhibited the participation of these groups to metal coordination or self-association by hydrogen bonding. This material selectively includes Cl(H2O)4- clusters in its channels, as revealed by single-crystal X-ray diffraction analysis, which represents the first structural characterization of such a water−chloride cluster.