Process-Tracing Study on the Postassembly Modification of Highly Stable Zirconium Metal–Organic Cages

Abstract

Metal-organic cages (MOCs) are discrete molecular assemblies formed by coordination bonds between metal nodes and organic ligands. The application of MOCs has been greatly limited due to their poor stability, especially in aqueous solutions. In this work, we thoroughly investigate the stability of several Zr-MOCs and reveal their excellent stability in aqueous solutions with acidic, neutral, and weak basic conditions. In addition, we present for the first time a process-tracing study on the postassembly modification of one MOC, ZrT-1-NH, highlighting the excellent stability and versatility of Zr-MOCs as a new type of molecular platform for various applications.

An Amine‐Functionalized Zirconium Metal–Organic Polyhedron Photocatalyst with High Visible‐Light Activity for Hydrogen Production

“…On the other hand, MOPs, which are stable under aqueous conditions, are highly desirable owing to extensive applications in aqueous environments, for example, in drug delivery and bioimaging . It is known that Zr‐MOFs are very stable in aqueous solutions; this could be ascribed to robust Zr−O bonds (Zr−O bond energy: 776 kJ mol −1 ) . Expanding upon research into Zr‐MOFs, some researchers have reported the synthesis of zirconium‐based MOPs, which are composed of trinuclear zirconium clusters and different carboxylate ligands .…”

“…Yuan and co‐workers synthesized a series of tetrahedral Zr‐MOPs, the stabilities of which were systematically studied at different pH values. All of these polyhedra exhibited excellent stability in acidic, neutral, and even alkaline aqueous solution environments . In 2017, Choe and co‐workers first reported a robust amine‐functionalized Zr‐MOP (UMOP‐1‐NH 2 , which was also referred to as ZrT‐1‐NH 2 in other work) with a similar tetrahedral cage, and presented cross connections with organic molecules through the condensation of amines in UMOP‐1‐NH 2 and acyl chlorides .…”

Stabilizing Metal–Organic Polyhedra (MOP): Issues and Strategies

“…The authors claimed this as the first example of covalent crosslinking between MOPs and, in fact, this could unite two distinct classes of materials, that is, MOPs and polymers, in a single composite. Recently, Zhao and co‐workers synthesized Zr‐MOCs (Figure a; MOC: metal–organic cage, synonymous to MOP) and studied their stability in aqueous media at different pH values . The cages were found to be exceptionally stable in neutral, acidic, and weakly basic aqueous environments (Figure b).…”

An Asymmetric Anion‐Pillared Metal–Organic Framework as a Multisite Adsorbent Enables Simultaneous Removal of Propyne and Propadiene from Propylene

“…Now an iobium oxide-fluoride anion-pillared interpenetrated material ZU-62 (NbOFFIVE-2-Cu-i, NbOFFIVE = NbOF 5 2À ) is presented. [3] As one of the most produced chemicals,p ropylene is the widely used monomer for the production of the polymers, requires the polymer-grade purity (> 99.5 %w ith propyne and propadiene less than 1ppm). The multisite capture mechanism was revealed by modeling studies.…”

“…[1] Especially towards the single component gas capture,t he amenable properties of the MOFs enable the possible design of customized pore structure for the specific molecule,j ust as the single molecule trap,w hich exhibiting excellent separation efficiencyf or various gas molecules. [3] As one of the most produced chemicals,p ropylene is the widely used monomer for the production of the polymers, requires the polymer-grade purity (> 99.5 %w ith propyne and propadiene less than 1ppm). Cascade removal based on the different adsorbents is still the dominant way,b ut is lowefficiency,complex, and high-cost.…”