Stoichiometry Controlled Structural Variation in Three-Dimensional Zn(II)–Frameworks: Single-Crystal to Single-Crystal Transmetalation and Selective CO₂ Adsorption

Abstract

Solvothermal reaction of the tripodal linker tris­(4′-carboxybiphenyl)­amine (H 3 L) and the colinker 3,5-di­(pyridin-4-yl)-4H-1,2,4-triazol-4-amine (dpta) in a different molar ratio produced 2-fold interpenetrated but structurally different three-dimensional Zn­(II) frameworks: {[Zn3(L)2­(dpta)­(DMF)]­·18DMF­·3H2O} n (1) and {[Zn3(L)2­(dpta)­(DMF)]­·14DMF­·3H2O} n (2) (L = L 3‑ , DMF = N,N′-dimethylformamide). Both the structures are built with a common [Zn3(COO)6] secondary building unit. While 1 is a pillared-bilayer framework with (43·624·8)­(43)2 topology, the construction of 2 is different due to altered disposition of SBUs and is describable by the Schlafli symbol (43.58.68.78.8)­(43)2. The structural variation alters the electronic environment and pore sizes in these frameworks, which allows the activated framework 2′ to uptake better N2 and H2 gases at 77 K, and CO2 at 273 K, than 1′. Compared to 1′, framework 2′ gives better selectivity of CO2 adsorption over N2, and H2 at 273 K, although the selectivity of CO2 over CH4 is reversed. Both 1 and 2 undergo transmetalation reactions with Cu­(II) at room temperature keeping crystalinity intact to generate 1 Cu and 2 Cu , respectively. The Cu-exchanged frameworks are characterized by single-crystal X-ray structures, while transmetalation kinetics are confirmed by energy-dispersive X-ray spectroscopy. In contrast to the activated Zn­(II) frameworks, the activated 1 Cu and 2 Cu are unstable and show no gas uptake.

Anion-Controlled Synthesis of Enantiomeric Twofold Interpenetrated 3D Zinc(II) Coordination Polymer with Ligand Substitution-Induced Single-Crystal-to-Single-Crystal Transformation and Photocatalysis

“…Coordination polymers (CPs) and metal–organic frameworks (MOFs) have been attractive to materials chemists especially in the most recent two decades because of their potential applications such as catalysis, separation, photoluminescence, and so on. On the one hand, a rational synthesis of crystalline CPs and MOFs with a desired functionality is truly a great challenge, because the phase formations of these moieties depend on the coordination chemistry of metals, the molecular geometry of linkers, and various synthetic parameters such as temperature, stoichiometry, etc. On the other hand, the single-crystal-to-single-crystal (SCSC) transformations of CPs and MOFs, typically associated with the change and/or modification of a chemical composition through various pathways, for example, solvation-desolvation, ligand substitution, and/or elimination as well as the modification of building components, are interesting due to a number of cooperative phenomena that probably enhance of the individual properties and even introduce new functionalities into the CPs and MOFs. , In the CPs and MOFs that incorporate long organic spacers, interpenetration can be thermodynamically incurred in these the structures that have a large free void in a single network. − In addition, a chiral three-dimensional (3D) network can be interpenetrated by its enantiomorphic frame giving a 3D “solid-state racemate” that was predicted and defined by Wells .…”

Energy-based descriptors for photo-catalytically active metal–organic framework discovery

“…The CSD reference codes and the chemical composition considering the constituent ligands are provided main chemical compositions. The systems cover a wide range of properties from single-crystal transmetalation reactions reported for 1, 2, 4 and 5,72,74,75 to selective CO 2 capture for 8 78. Notably, UV-visible absorption has been experimentally reported for systems 3,73 7, 77 9 (ref.…”

Metal–Organic Frameworks of Cu(II) Constructed from Functionalized Ligands for High Capacity H2 and CO2 Gas Adsorption and Catalytic Studies

“…The gas adsorption selectivity for both the frameworks was measured 31 according to the ideal adsorbed solution theory (IAST) at 273 K up to 1 bar of pressure using singlecomponent adsorption isotherms for CO 2 , H 2 , and N 2 (Figure 10). From the Figure, it was clear that the amounts of N 2 and H 2 uptake were negligibly small, whereas a1 Me and a1 ipr adsorbed significant amounts of CO 2 .…”