A Recyclable Metal-Organic Framework as a Dual Detector and Adsorbent for Ammonia.

Recyclable materials for simultaneous detection and uptake of ammonia (NH3 ) are of great interest due to the hazardous nature of NH3 . The structural versatility and porous nature of metal-organic frameworks (MOFs) make them ideal candidates for NH3 capture. Herein, the synthesis of a water-stable and porous 3-dimensional CuII -based MOF (SION-10) displaying a ship-in-a-bottle structure is reported; the pores of the host SION-10 framework accommodate mononuclear CuII -complexes. SION-10 spontaneously uptakes NH3 as a result of two concurrent mechanisms: chemisorption due to the presence of active CuII sites and physisorption (bulk permanent porosity). The color of the material changes from green to blue upon NH3 capture, with the shifts of the UV/Vis absorption bands clearly seen at NH3 concentrations as low as 300 ppm. SION-10 can be recovered upon immersion of SION-10⊃NH3 in water and can be further reused for NH3 capture for at least three cycles.

Size-selective yolk-shell nanoreactors with nanometer-thin porous polymer shells.

Yolk-shell nanoreactors with metal nanoparticle core and ultrathin porous polymer shells are effective catalysts for heterogeneous reactions. Polymer shells provide size-selectivity and improved reusability of catalyst. Nanocapsules with single-nanometer porous shells are prepared by vesicle-templated directed assembly. Metal nanoparticles are formed either by selective initiation in pre-fabricated nanocapsules or simultaneously with the creation of a crosslinked polymer shell. In this study, we investigated the oxidation of benzyl alcohol and benzaldehyde catalyzed by gold nanoparticles and hydrogenation of cyclohexene catalyzed by platinum nanoparticles. Comparison of newly created nanoreactors with commercially available nanoparticles revealed superior reusability and size selectivity in nanoreactors while showing no negative effect on reaction kinetics.

Silica Microspheres-in-Pores Composite Monoliths with Fluorescence and Potential for Water Remediation.

Water pollution is a severe worldwide issue. Constructing advanced porous composite materials has been an efficient route to water remediation via adsorption. In this study, a unique microspheres-in-pores monolithic structure was fabricated. An emulsion-templated polymer monolith was first prepared and silica microspheres were subsequently formed in the porous polymer. A silica precursor was modified with a fluorescent dye and co-condensed with other precursors to fabricate porous composites with fluorescent properties, which were enhanced by the presence of Ag nanoparticles in the polymer matrix. This unique material showed good promise in water remediation by removing organic dyes and heavy metal ions from wastewater via a flowing filter or monolithic column separation.

Bifunctional Noble-Metal-Free Catalyst for the Selective Aerobic Oxidation-Knoevenagel One-Pot Reaction: Encapsulation of Polyoxometalates into an Alkylamine-Modified MIL-101 Framework.

One-pot reactions offer economic and environmental advantages. Therefore, the design and synthesis of multifunctional catalysts capable of catalyzing multistep organic transformations are highly important. Herein, an effective bifunctional heterogeneous catalyst is presented. For the first time, the encapsulation of H5PMo10V2O40 (PMoV2) polyoxometalate into the cages of an alkylamine-modified MIL-101 using an optimized double-solvent method is reported. The obtained PMoV2@DETA-MIL-101 material displays a great catalytic performance (99% conversion of alcohols) for the selective aerobic oxidation-Knoevenagel one-pot reaction. To the best of our knowledge, this is one of the first reports on the usage of noble-metal-free catalysts for the aerobic oxidation-Knoevenagel one-pot reaction without the addition of additives. The catalyst is very stable and can be used for at least five cycles with no leaching of the active sites.

A "Ship-in-a-Bottle" strategy to create folic acid nanoclusters inside the nanocages of γ-cyclodextrin metal-organic frameworks.

Assembled between γ-cyclodextrins (CD) and potassium ions, γ-cyclodextrin metal-organic frameworks (CD-MOF) create spatially extended and ordered cage-like structures. Herein, it was demonstrated that folic acid (FA), a model molecule, could be densely packed inside CD-MOF reaching 2:1 FA:CD molar ratio. This "Ship-in-a-Bottle" strategy leads to a 1450 fold increase of the apparent solubility of FA. Moreover, the bioavailability of FA inside CD-MOF in rats was enhanced by a factor of 1.48 as compared to free FA. The unique mechanism of FA incorporation in the CD-MOF 3D network was also explored, which was different from the conventional CD inclusion complexation. Taylor dispersion investigations indicated that FA was incorporated on the basis of a two-component model, which was further supported by a set of complementary methods, including SEM, XRPD, BET, SR-FTIR, SAXS and molecular simulation. The hypothesized mechanism suggested that: i) tiny FA nanoclusters formed inside the hydrophilic cavities and onto the surface of CD-MOF and ii) FA was included inside dual-CD units in CD-MOF. In a nutshell, this dual incorporation mechanism is an original approach to dramatically increase the drug apparent solubility and bioavailability, and could be a promising strategy for other poorly soluble drugs.

Fluorescence labelling as tool for zeolite particle tracking in nanoremediation approaches.

Colloidal Fe-zeolites such as Fe-BEA-35 are currently under study as new adsorbent and catalyst materials for in-situ chemical oxidation with H2O2. As for nanoremediation in general, the availability of suitable particle detection methods is a requirement for successful process development and particle tracing. Detection and distinguishing between natural colloids and introduced particles with a similar composition are a challenge. By means of fluorescence labelling, a highly specific detection option for Fe-BEA-35 was developed. 'Ship-in-a-bottle' synthesis of fluorescein within the zeolite pores, which was applied for the first time for a BEA type zeolite, provides a product with stable and non-extractable fluorescence. When the fluorescent labelled zeolite is added at a concentration of 1wt.% referring to the total zeolite mass, a very low detection limit of 1mg/L of total zeolite is obtained. Compared to commonly applied turbidity measurements, detection via fluorescence labelling is much more specific and sensitive. Fluorescence is only marginally affected by carboxymethyl cellulose, which is frequently applied as stabilizer in application suspensions but will be depleted upon contact with H2O2. Transport properties of fluorescent labelled and non-labelled Fe-zeolite particles are in agreement as determined in a column study with quartz sand and synthetic groundwater (classified as very hard).