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

Abstract

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.

Anion Separation with Metal–Organic Frameworks

“…Along this line, we synthesized a cationic square-grid coordination network assembled from Cu 2+ and linker L15, which contained 1D channels functionalized with free -COOH binding groups (Figure 16). [77] The availability of free carboxylic groups in a coordination network is remarkable, as these groups typically become involved in the network assembly through coordination to the metal centers or hydrogen bonding. The key factors for the formation of this functional MOF appear to be the low pH (1.6) involved in its synthesis, which kept the carboxylic groups protonated and thus unavailable for metal coordination, and the aqueous solvent, which prevented the -COOH groups from self-associating by hydrogen bonding.…”

Synthesis and Structural Characterization of New Lead(II) Discrete and Infinite Cage-Like Framework: A Precursor to Produce Pure Phase Nano-Sized Lead(II) Oxide

“…Although channel surface modification is essential for the creation of functionalized porous structures, application of this synthetic approach to the PCP system has received little attention. Two types of strategies are used to functionalize channel surfaces: immobilization of coordinatively unsaturated (open) metal sites (OMS) and introduction of organic groups to provide guest-accessible functional organic sites (FOS) [6,7]. There is a growing interest in the use of OMS for Lewis acid catalysis and specific gas adsorption, but less attention has been paid to the study of FOS despite their importance.…”

A Series of 3D Lanthanide Complexes Containing (La(III), Sm(III) and Gd(III)) Metal-organic Frameworks: Synthesis, Structure, Characterization and Their Luminescent Properties

“…Pyridine-2,6-dicarboxylic acid (H 2 PDA) and its deprotonated anions (HPDA − and PDA 2− tuned under appropriate pH value) adopt flexible, multidentate coordination sites, and therefore may potentially provide various coordination modes which are in favor of the construction of higher-dimensional MOFs frameworks. [51][52][53][54][55][56][57][58][59][60][61] These organic fragments may adopt not only diverse coordination binding modes such as terminal monodentate, chelating to one metal center, bridging bidentate in syn-syn, syn-anti, or anti-anti conguration to metal centers, but also supramolecular contacts such as hydrogen bonding, π-π interactions, etc.…”