Zeolite-like Topology Research Articles

Pentazolate Anion: A Rare and Preferred Five-Membered Ligand for Constructing Pentasil-Zeolite Topology Architectures.

As the fourth full-nitrogen structure, the pentazolate anion (cyclo-N5 - ) was highly coveted for decades. In 2017, the first air-stable non-metal pentazolate salt, (N5 )6 (H3 O)3 (NH4 )4 Cl, was obtained, representing a milestone in this field. As the latest member of the azole family, cyclo-N5 - is comprised of five nitrogen atoms. Although significant attention has been paid to the potential of cyclo-N5 - as an energetic material, its poor thermostability hinders any practical application. However, the unique ring structure and multiple coordination capability of cyclo-N5 - provide a platform for the fabrication of various structures, among which pentasil-zeolite topologies are the most intriguing. In addition, the introduction of structure-directing auxiliaries enables the self-assembly of diverse topological architectures, potentially imparting cyclo-N5 - with the potential to impact wide-ranging areas of coordination chemistry and topology. In this minireview, different pentasil-zeolite topologies based on metal-pentazolate frameworks are evaluated. To date, three zeolitic and zeolite-like topologies have been reported, namely the melanophlogite (MEP), chibaite (MTN), and unj topologies. The MEP topology consists of two nanocages, Na20 N60 and Na24 N60 , whereas the MTN topology contains Na20 N60 and Na28 N80 nanocages. Furthermore, the unj topology features multiple homochiral channels consisting of two helical chains. Various possible strategies for obtaining additional pentasil-zeolite topologies are also discussed.

Biomimetic mineralization of lipase@MOF biocatalyst for ease of biodiesel synthesis: Structural insights into the catalytic behavior

A hybrid lipase@ZIF-8 biocatalyst was fabricated via a facile one-pot approach and coordination-driven self-assembly strategy. Entrapment immobilization of lipase in metal–organic frameworks (MOFs) was meticulously validated. The reduced Km value and apparent activation energy confirmed that the lipase@ZIF-8 registered a superior enzyme-substrate affinity than free ones. A concomitant conformational rearrangement occurred as lipase was encapsulated into the porous zeolite-like topologies, wherein lipase architectures presented more flexibility in character. An approximate 75% biodiesel yield was achieved when the biocomposites-catalyzed transesterification was conducted at given conditions. Notably, the lipase@ZIF-8 exhibited certain substrate-selectivity by deciphering the discrepancy in fatty acid profiles of the resulting biodiesel. Besides, the lipase@ZIF-8 biocomposites showed reasonable reusability and remained around 80% of initial activity after five cycles of transesterification. Consequently, the encapsulation of lipase into MOFs is a viable and sustainable avenue to address free lipase's intrinsic limitation, and underscores the immense potential in biodiesel production.

Recent progress in the design and synthesis of zeolite-like metal-organic frameworks (ZMOFs).

This article highlights recent examples of the design and synthesis of zeolite-like metal-organic frameworks (ZMOFs). ZMOFs are a subset of metal-organic frameworks (MOFs) that exhibit the same topologies as traditional inorganic zeolites. These frameworks have attracted research interest because of their unique pore systems and distinctive cage-based cavities. With the adoption of a molecular building block (MBB) strategy, many ZMOFs with high stability and performance can be rationally designed and synthesized using various secondary building units (SBUs).

Rational design and synthesis of an amino-functionalized hydrogen-bonded network with an ACO zeolite-like topology for gas storage

The modification of amino groups on the surface of In8 cubic SBUs comprising hydrogen-bonded networks with an ACO zeolite-like topology resulted in a great improvement in gas adsorption.

A new magnesium-containing aluminophosphate with a zeolite-like structure

A novel Mg-containing aluminophosphate JU96 is presented, which exhibits a new 4-connected zeolite-like topology with intersecting 8-ring channels.

Synthesis of Zeolitic Imidazolate Framework Core-Shell Nanosheets Using Zinc-Imidazole Pseudopolymorphs.

Zeolitic imidazolate frameworks (ZIFs) are an emerging class of microporous materials that possess an organic flexible scaffold and zeolite-like topology. The catalytic and molecular-separation capabilities of these materials have attracted considerable attention; however, crystal-shape engineering in ZIF materials remains in its infancy. This is the first study to report an effective method for tailoring the near-spherical crystal morphology of ZIF-8 using its leaf-like pseudopolymorph, ZIF-L. A thin, uniform layer of ZIF-8 is formed on ZIF-L through heterogeneous surface growth to produce a ZIF-L@ZIF-8 core-shell nanocomposite. This results in ZIF-8 with a crystal morphology comprising two-dimensional nanoflakes. We characterized the resulting core-shell crystals using a number of solid-state techniques, including powder X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and nitrogen physisorption. Approximately 16 mass% of ZIF-8 in the core-shell composites heterogeneous surfacely grown on ZIF-L core crystals. We also investigated the effects of zinc salts, which were used as a source of zinc in the formation of the ZIF-L@ZIF-8 core-shell nanocomposites. Finally, we assessed the CO2 adsorption properties of ZIF-8, ZIF-L, and ZIF-L@ZIF-8 core-shell crystals, the results of which were used to deduce the dynamic and equilibrium adsorption characteristics of various microporous ZIF crystals. The core-shell materials present hybridized CO2 uptake and diffusivity of the parent crystals. The proposed method for the synthesis of core-shell nanocomposites using pseudopolymorphic crystals is applicable to other ZIF systems.

Insights into the Molecular Assembly of Zeolitic Imidazolate Frameworks by ESI-MS

ZIFs are an interesting class of MOFs with zeolite-like topologies, owing to their structural similarities. Rational design and synthesis of ZIFs are highly challenging due to limited understanding of their formation process from solution, as previous studies were largely on crystal growth and properties. In this contribution, we describe a systematic approach to synthesize well-defined ZIF-8 crystals at different rates of nucleation by adjusting zinc to 2-methylimidazole ratios. For the first time, we report discrete chemical species detected in ZIF-8 synthesis and trace their transition with time using ESI-MS. Cravillon et al. have previously described three essential steps in ZIF-8 nucleation: (i) complex formation, (ii) complex deprotonation, and (iii) ligand exchange and oligomerization. In our work, we were able to identify species undergoing the various steps and correlate their evolution to the different nucleation rates. Applying ESI-MS in both positive and negative modes, we identified two speci...

Reference diffraction patterns, microstructure, and pore-size distribution for the copper (II) benzene-1,3,5-tricarboxylate metal organic framework (Cu-BTC) compounds

Cu-paddle-wheel-based Cu3(BTC)2 (nicknamed Cu-BTC, where BTC ≡ benzene 1,3,5-tricarboxylate) is a metal organic framework (MOF) compound that adopts a zeolite-like topology. We have determined the pore-size distribution using the Gelb and Gubbins technique, the microstructure using small-angle neutron scattering and (ultra) small-angle X-ray scattering (USAXS\SAXS) techniques, and X-ray powder diffraction reference patterns for both dehydrated d-Cu-BTC [Cu3(C9H3O6)2] and hydrated h-Cu-BTC [Cu3(C9H3O6)2(H2O)6.96] using the Rietveld refinement technique. Both samples were confirmed to be cubic Fm$\bar 3$m (no. 225), with lattice parameters of a = 26.279 19(3) Å, V = 18 148.31(6) Å3 for d-Cu-BTC, and a = 26.3103(11) Å, and V = 18 213(2) Å3 for h-Cu-BTC. The structure of d-Cu-BTC contains three main pores of which the diameters are approximately, in decreasing order, 12.6, 10.6, and 5.0 Å. The free volume for d-Cu-BTC is approximately (71.85 ± 0.05)% of the total volume and is reduced to approximately (61.33 ± 0.03)% for the h-Cu-BTC structure. The d-Cu-BTC phase undergoes microstructural changes when exposed to moisture in air. The reference X-ray powder patterns for these two materials have been determined for inclusion in the Powder Diffraction File.

Effect of Synthesis Parameters on the Formation of Zeolitic Imidazolate Framework 8 (ZIF-8) Nanoparticles for CO2 Adsorption

Zeolitic imidazole frameworks-8 (ZIF-8) is a subclass of metal-organic frameworks (MOFs) with the transition metal cations (Zn2+) linked by imidazolate anions forming tetrahedral frameworks in zeolite-like topologies. This article reports on the synthesis of ZIF-8 nanoparticles by varying the synthesis parameters at room temperature. The crystallization duration, molar ratios, and pH of the mixture solution were varied in order to study the effects of these parameters on the formation of ZIF-8 nanoparticles. The structural and morphology transformation of the resultant particles were characterized using x-ray diffraction, field emission scanning electron microscopy, and Brunauer–Emmett–Teller (BET) surface analysis. The CO2 adsorption characteristics of ZIF-8 nanoparticles were tested using CO2 physisorption analysis. Mature structural evolution was observed for ZIF-8 synthesized at 60 and 1440 min, but insufficient crystallization was found for ZIF-8 synthesized at 5 min. Meanwhile, ZIF-8 nanoparticles synthesized under lower amount of methanol resulted in larger particle size and higher crystallinity. Poorly intergrown ZIF-8 nanoparticles were observed for samples synthesized using a mixture solution with pH 8.2. Although different particle sizes and relative crystallinities were obtained for the ZIF-8 samples, synthesis using different molar ratios of the mixture solution, insignificant variations of BET surface areas, and CO2 adsorption capacities were found.

Porous Lithium Imidazolate Frameworks Constructed with Charge‐Complementary Ligands

Metal-organic frameworks (MOFs) based on 4-connected nodes are of special interest because of their zeolite-like topologies and open architectures.[1–2] A fundamental structural feature of zeolite topology is tetrahedral nodes (e.g., Si4+) crosslinked by a bicoordinated bridge (e.g., O2− as in SiO2). This bonding feature can be emulated by metal cations (or clusters) and organic crosslinking ligands. Until now, several metallic elements (e.g., Zn, Cd, and In) have been found to generate zeolite-like MOFs including zeolitic imidazolate frameworks (ZIFs) and indium-based ZMOFs.[3–6] The replacement of these transition (or post-transition) metals with lightweight main group metals (e.g., Li, Mg, and Al) has potential to produce a lower framework density, which is desirable for enhancing gravimetric energy storage capacity of gas storage materials. In the past several years, the synthesis of MOFs based on lightweight metals has attracted much attention with the greatest successes being achieved in Mg- and Al-MOFs.[7–8] Nevertheless, to date, the framework based on only 4-connected lithium nodes remains unknown, even though Li-containing boron imidazolate frameworks and frameworks containing Li-O clusters or chains are known.[9]

A New 2D Coordination Polymer Material Based on 4d-4f Heterometallic Assembly

A new transition-lanthanide metal-organic framework coordination complex, namely [Ag2Dy(nic)4(H2O)4· ClO4· H2O]n (nic = nicotinate) (1) has been synthesized by the reaction of the 4d and 4f metal salts with heterocyclic ligand under mild condition and characterized by elemental analysis, IR and single-crystal X-ray diffraction. Compound 1 presents interesting 2D under heterometallic layer generated by the self-assembly of 1D chains of lanthanide-carboxylate with Ag(nic)2 subunits. Furthermore, the title compound displays an interesting 3D zeolite-like porous topology.

Exceptional Stability and High Hydrogen Uptake in Hydrogen-Bonded Metal−Organic Cubes Possessing ACO and AST Zeolite-like Topologies

Herein we detail a novel approach for targeting zeolite-like metal-organic frameworks (ZMOFs) that utilizes metal-organic cubes, which are regarded as double four-membered rings (d4Rs) and are composite building units (BUs) in traditional inorganic zeolites. Accordingly, we outline the successful implementation of this strategy by reporting two ZMOFs with ACO and AST zeolite-like topologies, which were constructed from d4R BUs exclusively held together by hydrogen bonds. Their porosity was evaluated, delineating high hydrogen uptake and exceptional stability for the two hydrogen-bonded materials.

Self‐Assembly of Polyoxo Clusters and Extended Frameworks by Controlled Hydrolysis of Low‐Valent Uranium

Cores for celebration! Hydrolysis of trivalent uranium compounds with a stoichiometric amount of water leads to mixed-valence (UIV/UV) discrete clusters with the U6O8 core and with the unprecedented U12O20 core (see picture, right; U green, O red), and to the assembly of U6O8 clusters into extended 3D networks of zeolite-like topology with nanosized cavities (left; U pink, K violet, O red, F green).

Synthesis, Structure, and Luminescent and Magnetic Properties of Novel Lanthanide Metal−Organic Frameworks with Zeolite-like Topology

A series of microporous lanthanide metal-organic frameworks [Ln(BTC)(DMF)(2) x H(2)O, Ln = Tb (1), Dy (2), Ho (3), Er (4), Tm (5), Yb (6); DMF = N,N'-dimethylformamide] with 4 x 4 x 4 x 6 x 6 x 8 topology, which is very common in the zeolite topologies, have been synthesized under mild conditions. The single-crystal X-ray diffraction analysis reveals that they exhibit the same three-dimensional (3D) architecture and crystallize in monoclinic symmetry space group C2/c. Organic and inorganic four-connected nodes link each other to form a 3D open framework. The framework contains approximate 13 Angstrom x 7 Angstrom rectangle channels along the [1,1,0] and [1,-1,0] directions, respectively. The luminescent properties of these complexes have been studied, and complex 1 shows a Tb(3+) characteristic emission in the range of 450-650 nm at room temperature. Complexes 1-5 exhibit antiferromagnetic interaction between Ln(3+) ions. The water sorption isotherm shows that about 15 water molecules per unit cell can be adsorbed into the micropores of dehydrated complex 4.

Design and Generation of Extended Zeolitic Metal–Organic Frameworks (ZMOFs): Synthesis and Crystal Structures of Zinc(II) Imidazolate Polymers with Zeolitic Topologies

Attempts to create metal-organic frameworks (MOFs) with zeolitic topologies, metal (zinc(II) and cobalt(II)) imidazolates have repeatedly been used as the metal-organic motifs of inorganic silicate analogues. By modulating the synthetic strategy based on the solvothermal and liquid diffusion method, seven further MOFs (including at least three zeolitic MOFs) of zinc(II) imidazolates, [Zn(im)2.x G] (G=guest molecule, x=0.2-1) 1 a-7 a, have been successfully synthesized. Of these, 1 a-3 a are isostructural with the previously reported cobalt analogues 1 b-3 b, respectively, while 4 a-7 a are new members of the metal imidazolate MOF family. Complex 4 a exhibits a structure related to silicate CaAl2Si2O8 of CrB4 topology, but with a higher network symmetry; complex 5 a has a structure with zeolitic DFT topology that was discovered in zeolite-related materials of DAF-2, UCSB-3, and UCSB-3GaGe; complex 6 a demonstrates an unprecedented zeolite-like topology with one dimensional channels with 10-rings; and 7 a displays a structure of natural zeolite GIS (gismondine) topology. All of these polymorphous MOFs were created only by using certain solvents as structure-directing agents (SDAs). Further extensive metal-organic frameworks with zeolitic topologies can be envisaged if other solvents were to be used.

Organometallic molecular materials: self-assembly through hydrogen bonding of an organoplatinum network structure with zeolite-like topology

The complex [Pt(OH)(2)Me(2)(dpa)], dpa = di-2-pyridylamine, undergoes a remarkable form of self-assembly through hydrogen bonding in the solid state; there are cyclic tetramer units formed by head-to-head association between pairs of hydroxyl groups, and cyclic hexamer units formed by head-to-tail association between NH and OH groups; these building blocks then self-assemble to form a complex network structure containing large interconnected cavities, reminiscent of zeolites.

Porous lanthanide–organic framework with zeolite-like topology

Two novel isomorphous porous frameworks of Ln(III), {[Ln2(imidc)2(H2O)3](H2O)}n, [Ln = Gd(III) (1) and Er(III) (2)] have been synthesized hydrothermally using multifunctional 4,5-imidazoledicarboxylic acid (imidc) as a connector; they have a zeolite-like network topology which can provide another form upon dehydration, and exhibit selective adsorption properties for H2O over N2, CO2 and MeOH.

Co5(im)10⋅2 MB]∞: A Metal-Organic Open-Framework with Zeolite-Like Topology

A highly robust metal-organic zeotype was created by expansion of the zeolite topology. The novel nanoporous material [Co5(im)10⋅2 MB]∞ (see structure) exhibits not only a zeolite-like topology, but also the chemically functionalizable properties of zeolites; im=imidazole, MB=3-methyl-1-butanol.

Co5(im)10⋅2 MB]∞: A Metal-Organic Open-Framework with Zeolite-Like Topology This work was funded by the State Key Project of Fundamental Research (No. G200077500) and the Natural Science Foundation of China. We thank Prof. Dr. Ren-Gen Xiong for production of figures. im=imidazole; MB=3-methyl-1-butanol.

Ein hoch robuster metallorganischer Zeotyp wurde durch Expandieren der Zeolithtopologie hergestellt. Das neuartige nanoporöse Material [Co5(im)10⋅2 MB]∞ (siehe Struktur) hat nicht nur eine Zeolith-ähnliche Topologie, sondern weist auch die chemisch funktionalisierbaren Eigenschaften von Zeolithen auf. im=Imidazol; MB=3-Methyl-1-butanol.