Continuous Flow Synthesis of a Zr Magnetic Framework Composite for Post-Combustion CO2 Capture.

Metal-organic frameworks (MOFs) have an unprecedented ability to store gas molecules, however energy efficient regeneration remains challenging. Use of magnetic induction to aid this shows promise, but economical synthesis of the requisite composites is unresolved. Continuous flow chemistry has been reported as a rapid and reliable method of MOF synthesis, delivering step-change improvements in space time yields (STY). Here the scalable production of nanomaterials suitable for regeneration by magnetic induction is demonstrated. The zirconium MOF composite, MgFe2 O4 @UiO-66-NH2 is prepared using continuous flow chemistry resulting in a material of comparable performance to its batch counterpart. Upscaling using flow chemistry gave STY >25 times that of batch synthesis. Magnetic induced regeneration using this mass produced MFC for carbon capture is then demonstrated.

New synthetic routes towards MOF production at scale.

The potential commercial applications for metal organic frameworks (MOFs) are tantalizing. To address the opportunity, many novel approaches for their synthesis have been developed recently. These strategies present a critical step towards harnessing the myriad of potential applications of MOFs by enabling larger scale production and hence real-world applications. This review provides an up-to-date survey ( references) of the most promising novel synthetic routes, i.e., electrochemical, microwave, mechanochemical, spray drying and flow chemistry synthesis. Additionally, the essential topic of downstream processes, especially for large scale synthesis, is critically reviewed. Lastly we present the current state of MOF commercialization with direct feedback from commercial players.

"Dual-template" synthesis of one-dimensional conductive nanoparticle superstructures from coordination metal-peptide polymer crystals.

Bottom-up fabrication of self-assembled structures made of nanoparticles may lead to new materials, arrays and devices with great promise for myriad applications. Here a new class of metal-peptide scaffolds is reported: coordination polymer Ag(I)-DLL belt-like crystals, which enable the dual-template synthesis of more sophisticated nanoparticle superstructures. In these biorelated scaffolds, the self-assembly and recognition capacities of peptides and the selective reduction of Ag(I) ions to Ag are simultaneously exploited to control the growth and assembly of inorganic nanoparticles: first on their surfaces, and then inside the structures themselves. The templated internal Ag nanoparticles are well confined and closely packed, conditions that favour electrical conductivity in the superstructures. It is anticipated that these Ag(I)-DLL belts could be applied to create long (>100 µm) conductive Ag@Ag nanoparticle superstructures and polymetallic, multifunctional Fe3 O4 @Ag nanoparticle composites that marry the magnetic and conductive properties of the two nanoparticle types.

Coordination polymer nanofibers generated by microfluidic synthesis.

One-dimensional coordination polymer nanostructures are an emerging class of nanoscale materials with many potential applications. Here, we report the first case of coordination polymer nanofibers assembled using microfluidic technologies. Unlike common synthetic procedures, this approach enables parallel synthesis with an unprecedented level of control over the coordination pathway and facilitates the formation of 1D coordination polymer assemblies at the nanometer length scale. Finally, these nanostructures, which are not easily constructed with traditional methods, can be used for various applications, for example as templates to grow and organize functional inorganic nanoparticles.

Amino acid based metal-organic nanofibers.

Long chiral metal-organic nanofibers can be grown using conventional coordination chemistry and biologically derived components in a diffusion controlled growth procedure.

Leucine zipper motif inspiration: a two-dimensional leucine Velcro-like array in peptide coordination polymers generates hydrophobicity.

Here, we show that the well-known hydrophobic leucine (Leu) zipper motif (also known as the coiled-coil or Leu scissors motif), typically found in proteins, can be used as a source of inspiration in coordination polymers built from Leu-containing dipeptides or tripeptides. We demonstrate that this motif can be extended to form Velcro-like layers of Leu, and that the hydrophobicity of these layers is transferred to coordination polymers, thereby enabling the development of a new type of hydrophobic materials.

Double-Sided Electrochromic Device Based on Metal-Organic Frameworks.

Devices displaying controllably tunable optical properties through an applied voltage are attractive for smart glass, mirrors, and displays. Electrochromic material development aims to decrease power consumption while increasing the variety of attainable colors, their brilliance, and their longevity. We report the first electrochromic device constructed from metal organic frameworks (MOFs). Two MOF films, HKUST-1 and ZnMOF-74, are assembled so that the oxidation of one corresponds to the reduction of the other, allowing the two sides of the device to simultaneously change color. These MOF films exhibit cycling stability unrivaled by other MOFs and a significant optical contrast in a lithium-based electrolyte. HKUST-1 reversibly changed from bright blue to light blue and ZnMOF-74 from yellow to brown. The electrochromic device associates the two MOF films via a PMMA-lithium based electrolyte membrane. The color-switching of these MOFs does not arise from an organic-linker redox reaction, signaling unexplored possibilities for electrochromic MOF-based materials.

Defect engineering of UiO-66 for CO2 and H2O uptake - a combined experimental and simulation study.

Defect concentrations and their compensating groups have been systematically tuned within UiO-66 frameworks by using modified microwave-assisted solvothermal methods. Both of these factors have a pronounced effect on CO2 and H2O adsorption at low and high pressure.

Scalability of Continuous Flow Production of Metal-Organic Frameworks.

Achieving the large-scale production of metal-organic frameworks (MOFs) is crucial for their utilization in applied settings. For many MOFs, quality suffers from large-scale, batch reaction systems. We have developed continuous processes for their production which showed promise owing to their versatility and the high quality of the products. Here, we report the successful upscaling of this concept by more than two orders of magnitude to deliver unprecedented production rates and space-time-yields (STYs) while maintaining the product quality. Encouragingly, no change in the reaction parameters, obtained at small scale, was required. The production of aluminium fumarate was achieved at an STY of 97 159 kg m(-3)  day(-1) and a rate of 5.6 kg h(-1) .

Freezing the Nonclassical Crystal Growth of a Coordination Polymer Using Controlled Dynamic Gradients.

A methodology that can be efficiently used to synthesize, isolate, and study out-of-equilibrium crystal structures employing controlled and diffusion-limited microfluidic environments is demonstrated. Unlike studies conducted with conventional mixing procedures in a flask, it is proven experimentally and with numerical simulations that microfluidic technologies can undoubtedly fine-tune reaction times and reagents concentration profiles; factors that enable out-of-equilibrium crystal forms to be obtained.

Versatile, high quality and scalable continuous flow production of metal-organic frameworks.

Further deployment of Metal-Organic Frameworks in applied settings requires their ready preparation at scale. Expansion of typical batch processes can lead to unsuccessful or low quality synthesis for some systems. Here we report how continuous flow chemistry can be adapted as a versatile route to a range of MOFs, by emulating conditions of lab-scale batch synthesis. This delivers ready synthesis of three different MOFs, with surface areas that closely match theoretical maxima, with production rates of 60 g/h at extremely high space-time yields.

Localized, stepwise template growth of functional nanowires from an amino acid-supported framework in a microfluidic chip.

A spatially controlled synthesis of nanowire bundles of the functional crystalline coordination polymer (CP) Ag(I)TCNQ (tetracyanoquinodimethane) from previously fabricated and trapped monovalent silver CP (Ag(I)Cys (cysteine)) using a room-temperature microfluidic-assisted templated growth method is demonstrated. The incorporation of microengineered pneumatic clamps in a two-layer polydimethylsiloxane-based (PDMS) microfluidic platform was used. Apart from guiding the formation of the Ag(I)Cys coordination polymer, this microfluidic approach enables a local trapping of the in situ synthesized structures with a simple pneumatic clamp actuation. This method not only enables continuous and multiple chemical events to be conducted upon the trapped structures, but the excellent fluid handling ensures a precise chemical activation of the amino acid-supported framework in a position controlled by interface and clamp location that leads to a site-specific growth of Ag(I)TCNQ nanowire bundles. The synthesis is conducted stepwise starting with Ag(I)Cys CPs, going through silver metal, and back to a functional CP (Ag(I)TCNQ); that is, a novel microfluidic controlled ligand exchange (CP → NP → CP) is presented. Additionally, the pneumatic clamps can be employed further to integrate the conductive Ag(I)TCNQ nanowire bundles onto electrode arrays located on a surface, hence facilitating the construction of the final functional interfaced systems from solution specifically with no need for postassembly manipulation. This localized self-supported growth of functional matter from an amino acid-based CP shows how sequential localized chemistry in a fluid cell can be used to integrate molecular systems onto device platforms using a chip incorporating microengineered pneumatic tools. The control of clamp pressure and in parallel the variation of relative flow rates of source solutions permit deposition of materials at different locations on a chip that could be useful for device array preparation. The in situ reaction and washing procedures make this approach a powerful one for the fabrication of multicomponent complex nanomaterials using a soft bottom-up approach.

Metal-biomolecule frameworks (MBioFs).

Biomolecules are the building blocks of life. Nature has evolved countless biomolecules that show promise for bridging metal ions. These molecules have emerged as an excellent source of biocompatible building blocks that can be used to design Metal-Biomolecule Frameworks (MBioFs). This feature article highlights the advances in the synthesis of this class of MOFs. Special emphasis is provided on the crystal structures of these materials, their miniaturization to the submicron length scale, and their new potential storage, catalytic, and biomedical applications.

Coordination polymer particles as potential drug delivery systems.

Micro- and nanoscale coordination polymer particles can be used for encapsulating and delivering drugs. In vitro cancer cell cytotoxicity assays showed that these capsules readily release doxorubicin, which shows anticancer efficacy. The results from this work open up new avenues for metal-organic capsules to be used as potential drug delivery systems.