Immobilization of MP-11 into a Mesoporous Metal–Organic Framework, MP-11@mesoMOF: A New Platform for Enzymatic Catalysis

A green approach to the synthesis of novel "Desert rose stone"-like nanobiocatalytic system with excellent enzyme activity and stability

3D hierarchical layer double hydroxides (LDHs) have attracted extensive interest due to their unique electronic and catalytic properties. Unfortunately, the existing preparation methods require high temperature or toxic organic compounds, which limits the applications of the 3D hierarchical LDHs in biocatalysis and biomedicine. Herein, we present a green strategy to synthesize “Desert Rose Stone”-like Mg-Al-CO₃ LDH nanoflowers in situ deposited on aluminum substrates via a coprecipitation method using atmospheric carbon dioxide. Using this method, we construct a novel “Desert Rose Stone”-like nanobiocatalytic system by using HRP as the model enzyme. Compared with the free HRP, the HRP/Mg-Al-LDH nanobiocatalytic system exhibits higher catalytic activity and stability. A smaller apparent Michaelis-Menten constant (0.16 mM) of this system suggests that the encapsulated HRP shows higher affinity towards H₂O₂.

One-pot synthesis of protein-embedded metal-organic frameworks with enhanced biological activities

Protein molecules were directly embedded in metal-organic frameworks (MOFs) by a coprecipitation method. The protein molecules majorly embedded on the surface region of MOFs display high biological activities. As a demonstration of the power of such materials, the resulting Cyt c embedded in ZIF-8 showed a 10-fold increase in peroxidase activity compared to free Cyt c in solution and thus gave convenient, fast, and highly sensitive detection of trace amounts of explosive organic peroxides in solution.

Highly mesoporous metal-organic framework assembled in a switchable solvent

The mesoporous metal-organic frameworks are a family of materials that have pore sizes ranging from 2 to 50 nm, which have shown promising applications in catalysis, adsorption, chemical sensing and so on. The preparation of mesoporous metal-organic frameworks usually needs the supramolecular or cooperative template strategy. Here we report the template-free assembly of mesoporous metal-organic frameworks by using CO2-expanded liquids as switchable solvents. The mesocellular metal-organic frameworks with large mesopores (13-23 nm) are formed, and their porosity properties can be easily adjusted by controlling CO2 pressure. Moreover, the use of CO2 can accelerate the reaction for metal-organic framework formation from metal salt and organic linker due to the viscosity-lowering effect of CO2, and the product can be recovered through CO2 extraction. The as-synthesized mesocellular metal-organic frameworks are highly active in catalysing the aerobic oxidation of benzylic alcohols under mild temperature at atmospheric pressure.

Fast multipoint immobilized MOF bioreactor

An enzyme-NBD@MOF bioreactor with exemplary proteolytic performance, even after successive reuse and storage, was produced through a novel, rapid and simple multipoint immobilization technique without chemical modification of the solid support. Enzyme loading and distribution could be directly monitored from the fluorescence emission of the bioreactor. The dye molecular dimension plays a role in its overall performance.

Introduction of π-complexation into porous aromatic framework for highly selective adsorption of ethylene over ethane

In this work, we demonstrate for the first time the introduction of π-complexation into a porous aromatic framework (PAF), affording significant increase in ethylene uptake capacity, as illustrated in the context of Ag(I) ion functionalized PAF-1, PAF-1-SO3Ag. IAST calculations using single-component-isotherm data and an equimolar ethylene/ethane ratio at 296 K reveal that PAF-1-SO3Ag shows exceptionally high ethylene/ethane adsorption selectivity (Sads: 27 to 125), far surpassing benchmark zeolite and any other MOF reported in literature. The formation of π-complexation between ethylene molecules and Ag(I) ions in PAF-1-SO3Ag has been evidenced by the high isosteric heats of adsorption of C2H4 and also proved by in situ IR spectroscopy studies. Transient breakthrough experiments, supported by simulations, indicate the feasibility of PAF-1-SO3Ag for producing 99.95%+ pure C2H4 in a Pressure Swing Adsorption operation. Our work herein thus suggests a new perspective to functionalizing PAFs and other types of advanced porous materials for highly selective adsorption of ethylene over ethane.

Thin-layer polymer wrapped enzymes encapsulated in hierarchically mesoporous silica with high activity and enhanced stability

A novel soft-hard cooperative approach was developed to synthesize bioactive mesoporous composite by pre-wrapping Penicillin G amidase with poly(acrylaimde) nanogel skin and subsequently incorporating such Penicillin G amidase nanocapsules into hierarchically mesoporous silica. The as-received bioactive mesoporous composite exhibited comparable activity and extraordinarily high stability in comparison with native Penicillin G amidase and could be used repetitively in the water-medium hydrolysis of penicillin G potassium salt. Furthermore, this strategy could be extended to the synthesis of multifunctional bioactive mesoporous composite by simultaneously introducing glucose oxidase nanocapsules and horseradish peroxidase nanocapsules into hierarchically mesoporous silica, which demonstrated a synergic effect in one-pot tandem oxidation reaction. Improvements in the catalytic performances were attributed to the combinational unique structure from soft polymer skin and hard inorganic mesoporous silica shell, which cooperatively helped enzyme molecules to retain their appropriate geometry and simultaneously decreased the enzyme-support negative interaction and mass transfer limitation under heterogeneous conditions.

Functionalized aminocarboxylate moieties as linkers for coordination polymers: influence of the substituents in the dimensionality of the final structure

The OH group in the ring hampers the generation of CPs due to the formation of strong intermolecular interaction motifs.

Encapsulation of large dye molecules in hierarchically superstructured metal–organic frameworks

A perturbation assisted nanofusion technique to construct hierarchically superstructured MOFs was reported. In particular, the mesopores in the MOF structure enabled the confinement of large dye species, resulting in fluorescent dye@MOF composite materials.

MOF positioning technology and device fabrication

Methods for permanent localisation, dynamic localisation and spatial control of functional materials within MOF crystals are critical for the development of miniaturised MOF-based devices for a number of technological applications.

Mesoporous non-siliceous inorganic–organic hybrids: a promising platform for designing multifunctional materials

An overview of the recent progress in the designed synthesis, modification and multifunctional applications of mesoporous non-siliceous inorganic–organic hybrid materials including metal phosphonates, carboxylates and sulfonates is presented.

Post-synthetic metalation of metal–organic frameworks

Post-synthetic metalation (PSMet) offers expansive scope for a targeted approach to tailoring the properties of MOFs.

Protein Immobilization in Metal–Organic Frameworks by Covalent Binding

Metal–organic frameworks (MOFs), possessing a well defined system of pores, demonstrate extensive potential serving as a platform in biological catalysis. Successful immobilization of enzymes in a MOF system retains the enzymatic activity, renders the active site more accessible to the substrate, and promises recyclability for reuse, and solvent adaptability in a broad range of working conditions. This highlight describes enzyme immobilization on MOFs via covalent binding and its significance.

Metal phosphonate hybrid materials: from densely layered to hierarchically nanoporous structures

Inorganic–organic metal phosphonate hybrid materials with great diversity in structure and properties exhibit application potential in various fields.

A synthetic route to ultralight hierarchically micro/mesoporous Al(III)-carboxylate metal-organic aerogels

Developing a synthetic methodology for the fabrication of hierarchically porous metal-organic monoliths that feature high surface area, low density and tunable porosity is imperative for mass transfer applications, including bulky molecule capture, heterogeneous catalysis and drug delivery. Here we report a versatile and facile synthetic route towards ultralight micro/mesoporous metal-organic aerogels based on the two-step gelation of metal-organic framework nanoparticles. Heating represents a key factor in the control of gelation versus crystallization of Al(III)-multicarboxylate systems. The porosity of the resulting metal-organic aerogels can be readily tuned, leading to the formation of well-ordered intraparticle micropores and aerogel-specific interparticle mesopores, thereby integrating the merits of both crystalline metal-organic frameworks and light aerogels. The hierarchical micro/mesoporosity of the Al-metal-organic aerogels is thoroughly evaluated by N₂ sorption. The good accessibility of the micro/mesopores is verified by vapour/dye uptake, and their potential for utilization as effective fibre-coating absorbents is tested in solid-phase microextraction analyses.

Hierarchically porous metal-organic monoliths are potential materials for mass transfer applications. Here, the authors synthesize metal-organic aerogels via the gelation of metal-organic frameworks, and are able to tune their porosity exploiting the properties of both crystalline and aerogel materials.

Combining UV lithography and an imprinting technique for patterning metal-organic frameworks

Thin metal-organic framework (MOF) films are patterned using UV lithography and an imprinting technique. A UV lithographed SU-8 film is imprinted onto a film of MOF powder forming a 2D MOF patterned film. This straightforward method can be applied to most MOF materials, is versatile, cheap, and potentially useful for commercial applications such as lab-on-a-chip type devices.

The Chemistry and Applications of Metal-Organic Frameworks

Crystalline metal-organic frameworks (MOFs) are formed by reticular synthesis, which creates strong bonds between inorganic and organic units. Careful selection of MOF constituents can yield crystals of ultrahigh porosity and high thermal and chemical stability. These characteristics allow the interior of MOFs to be chemically altered for use in gas separation, gas storage, and catalysis, among other applications. The precision commonly exercised in their chemical modification and the ability to expand their metrics without changing the underlying topology have not been achieved with other solids. MOFs whose chemical composition and shape of building units can be multiply varied within a particular structure already exist and may lead to materials that offer a synergistic combination of properties.

Synthesis of MOFs

A summary of important – theoretical and practical – aspects, approaches and methods is presented, which are utilized in the synthesis of MOFs. Throughout the text the needs of scientists mainly working in the field of catalysis is addressed. Thus in the first half of the chapter, general principles and methods for crystallisation are briefly summarized, followed by detailed descriptions of the important concepts of isoreticular chemistry and high‐throughput methods. Moreover some examples are given for the use of precursors and templates. Topological rules that may affect the final MOF‐structure can also be utilised for the intentional synthesis of MOFs. The second half of the chapter will cover aspects that are more strongly correlated to materials chemistry – the shaping of crystals as well as the introduction of hierarchical mesopores into the particles and the anchoring of MOFs to surfaces. Finally, some important comments on the activation procedures are given, which determine the maximum porosity of a material and thus its catalytic activity. Thus, the text intends to give an insight into the diverse and sometimes complex field of the synthesis of MOFs.

Magnetic affinity microspheres with meso-/macroporous shells for selective enrichment and fast separation of phosphorylated biomolecules

The flowerlike multifunctional affinity microspheres prepared by a facile solvothermal synthesis and subsequent calcination process consist of magnetic cores and hierarchical meso-/macroporous TiO2 shells. The hierarchical porous structure of the flowerlike affinity microspheres is constructed by the macroporous shell from the stacked mesoporous nanopetals which are assembled by small crystallites. The affinity microspheres have a relatively large specific surface area of 50.45 m(2) g(-1) and superparamagnetism with a saturation magnetization (Ms) value of 30.1 emu g(-1). We further demonstrate that they can be applied for rapid and effective purification of phosphoproteins, in virtue of their selective affinity, porous structure, and strong magnetism. In addition, the affinity microspheres can also be used for enrichment of phosphopeptides, and the selectivity is greatly improved due to the increase of mass transport and prevention of the possible "shadow effect" resulting from the smaller and deeper pores by taking advantage of the unique porous structure. Overall, this work will be highly beneficial for future applications in the isolation and identification of phosphorylated biomolecules.

Formation of a metalloporphyrin-based nanoreactor by postsynthetic metal-ion exchange of a polyhedral-cage containing a metal-metalloporphyrin framework

A change for the better: Exchange of Cd(II) in the catalytically inactive framework MMPF-5 (see scheme) with Co(II) afforded a metalloporphyrin-based nanoreactor, MMPF-5(Co). This framework, consisting of small cubicuboctahedral cages, demonstrated interesting performances in the catalytic epoxidation of trans-stilbene with tBuOOH.

Novel trypsin-FITC@MOF bioreactor efficiently catalyzes protein digestion

A simple nanoporous metal organic framework (MOF) bioreactor preparation via a low energy 30 minute vortex as driving force to immobilize trypsin enzyme is presented. No chemical modifications were employed thus organic wastes were eliminated. The digestion efficiency of this trypsin bioreactor is exceptionally high, even when reused. This "green" synthesis procedure produced a "green" bioreactor.

A novel series of isoreticular metal organic frameworks: realizing metastable structures by liquid phase epitaxy

A novel class of metal organic frameworks (MOFs) has been synthesized from Cu-acetate and dicarboxylic acids using liquid phase epitaxy. The SURMOF-2 isoreticular series exhibits P4 symmetry, for the longest linker a channel-size of 3 × 3 nm² is obtained, one of the largest values reported for any MOF so far. High quality, ab-initio electronic structure calculations confirm the stability of a regular packing of (Cu⁺⁺)₂- carboxylate paddle-wheel planes with P4 symmetry and reveal, that the SURMOF-2 structures are in fact metastable, with a fairly large activation barrier for the transition to the bulk MOF-2 structures exhibiting a lower, twofold (P2 or C2) symmetry. The theoretical calculations also allow identifying the mechanism for the low-temperature epitaxial growth process and to explain, why a synthesis of this highly interesting, new class of high-symmetry, metastable MOFs is not possible using the conventional solvothermal process.