An efficient Cu(I)-catalyzed aerobic alcohol oxidation system was developed utilizing a novel metal–organic framework (MOF) ligand at room temperature. Several relatively inert secondary alcohols were converted to their corresponding ketones in high yields and selectivities in the presence of a Cu(I) catalyst and air as the oxidant. This newly developed Cu(I)/MOF ligand system can also be easily extended to the aerobic oxidation of primary alcohols including aliphatic ones. Furthermore, the MIL-101-N-2-pyc ligand can be recycled several times without compromising reaction activity.

A novel magnetic Fe3O4@P4VP(poly(4-vinylpyridine))@FeCl3 core–shell structure was successfully synthesized. Its Fe3O4@P4VP core was initially prepared via polymerization of 4-vinyl pyridine on the surface of Fe3O4 microspheres. The successful introduction of the FeCl3 moiety as a catalytic active site was achieved through coordination interaction between P4VP and FeCl3. The obtained Fe3O4@P4VP@FeCl3 catalyst was applied in the selective oxidation of alcohols using molecular oxygen as the oxidant. It was shown that a variety of alcohol substrates is tolerated under optimized reaction conditions. Additionally, benzylic oxidation of hydrocarbon compounds was also evaluated using Fe3O4@P4VP@FeCl3 as the catalyst and tBuOOH as the oxidant, achieving high yields and very good selectivities. The heterogeneity of the Fe3O4@P4VP@FeCl3 core–shell catalyst was tested and the initial activity was maintained after five reuses.

One of the major challenges in heterogeneous catalysis is how to suppress the aggregation of thermodynamically unstable noble metal nanoparticles (NPs) and simultaneously maintain their high accessibility. Here we report the fabrication of integrated functional nanostructures consisting of a dendritic porous silica yolk with many small noble metal NPs and a protective mesoporous silica shell (MSS) with perpendicularly aligned pore channels and tunable shell thickness by using a well-controlled interfacial engineering strategy. Three-dimensional (3D) dendrimer-like superstructures with many permeable center-radial large pore channels and a highly accessible internal surface area, named dendritic porous silica spheres (DPSSs), serve as unique yolks not only because of their capability to accommodate high density ultrafine Au or Pt NPs, but also their functionality to act as robust physical barriers to separate and confine the aforementioned loaded NPs, which result in slowing down their aggregation at high temperatures due to Ostwald ripening. These integrated hierarchical structures also ensure good stability under weak basic and acidic conditions. Due to their superior structural properties, the DPSSs@noble metal NPs@MSS yolk–shell structures exhibit excellent catalytic performance in p-nitrophenol reduction, epoxidation reaction and CO oxidation. The favorable stability and high catalytic performance of these yolk–shell structures make the developed design strategy very useful for the fabrication of novel highly active and stable catalysts.

A novel Zr-derived metal–organic framework (MOF) ligand was designed and synthesized, and found to effect efficient Cu(I)-catalyzed oxidations of secondary alcohols. The UiO-66-NH-PC solid ligand was utilized as an efficient oxidation reaction ligand. Several secondary alcohols were selectively transformed to ketones in good yields, using air as the oxidant, and under mild reaction conditions. In order to broaden the applicability of the method, various primary alcohols and benzylic compounds were also tested in the oxidation reaction, and afforded the corresponding aldehydes and ketones in very high yields. Finally, the recyclability of the synthesized UiO-66-NH-PC ligand was confirmed by reusing the same batch of catalyst up to five times without observing any decrease in reactivity.

Two Al–MIL-53 derived metal–organic frameworks (MOFs) were developed to serve as efficient heterogeneous Brønsted acid catalysts. Sulfonic acid functional groups were successfully incorporated into the framework by post-synthetic modification (PSM) using commercially available reagents. The synthesized Al–MIL-53–RSO3H and Al–MIL-53–ArSO3H Brønsted acid–MOF catalysts were fully characterized by SEM, powder XRD, FTIR, TGA and N2 adsorption/desorption isotherms. An efficient [4 + 2] cycloaddition of 2-vinyl-substituted phenols was evaluated using the newly synthesized Al–MIL-53–RSO3H and Al–MIL-53–ArSO3H catalysts. The Al–MIL-53–RSO3H and Al–MIL-53–ArSO3H catalysts were found to be compatible with a variety of substituted substrates; finally, they can be recycled five times without compromising the yield or selectivity of the reaction.

•A newly designed Fe3O4@P4VP@ZIF-8 core-shell catalyst is reported.•Layer-by-layer strategy was utilized to achieve core-shell structure at 400 nm.•The Fe3O4@P4VP@ZIF-8 core-shell material can be applied in an efficient Knoevenagel reaction.•Rapid catalyst recycling through external magnetic field.In this work, a core-shell magnetic composite Fe3O4@P4VP@ZIF-8 microspheres were successfully designed and synthesized. A polymerization approach on the surface of pre-made Fe3O4 microspheres was employed for the synthesis of Fe3O4@P4VP. The zinc-derived Zeolite Imidazolate Framework (ZIF) shell was introduced through a layer-by-layer strategy. The obtained Fe3O4@P4VP@ZIF-8 core-shell structure was employed as an efficient Knoevenagel condensation catalyst for a variety of aldehydes. Furthermore, the inner P4VP layer also served as a basic additive in the condensation reaction process, while much less homogeneous basic additive was used. High catalytic reaction efficiency was achieved when the P4VP layer was utilized in combination with a Lewis acidity bearing ZIF-8 layer. The Fe3O4@P4VP@ZIF-8 catalyst was tested for recyclability and no drop in the catalytic activity was observed after more than five cycles.Download high-res image (187KB)Download full-size image

•Molten salts/expanded graphite composite phase change materials were prepared.•The content of molten salts in the composites was from 77.8% to 81.5%.•Thermal conductivity of molten salts was enhanced after impregnation with EG.•Composites showed great thermal stability after 40 cycles.•Composites were designed for future use in cascaded latent heat storage.Three kinds of porous heterogeneous composite phase change materials were synthesized from expanded graphite (EG) and binary molten salts (LiNO3–KCl, LiNO3–NaNO3 and LiNO3–NaCl) through solution impregnation method. Binary molten salt content in the composite phase change materials was calculated to be between 77.8% and 81.5% and high encapsulation efficiency was calculated to be between 72.8% and 78.8%. The thermal conductivity of binary molten salts was enhanced by 4.9–6.9 times after impregnation with EG. SEM photographs showed that the prepared composites were more homogeneous in comparison to other salt/EG composites prepared by infiltration or compression. Phase change properties of the porous heterogeneous composite phase change materials showed great thermal stability, which was maintained after 100 cycles.

A novel HAuCl4@UiO-66-NH2 material has been obtained and utilized as a heterogeneous Au(III) catalyst. This Au(III) catalyst was able to promote the formation of a variety of dihydrochalcones starting from 2H-chromenes in moderate to good yields. A tandem hydride shift/hydration reaction sequence has been proposed based on deuterium labeling studies, which revealed a 1,5-hydride shift reaction pathway. A flavone intermediate has been synthesized to further support the proposed mechanism. Furthermore, the HAuCl4@UiO-66-NH2 catalyst can be recycled several times without compromising the catalytic activity.

We synthesized hierarchical Polystyrene/Polyaniline@Au (PS/PANI@Au) catalysts through a seeded swelling polymerization and in-situ reduction procedure. PS/PANI@Au catalysts possess a core of PS as seed and template, a PANI shell with fibers and uniform gold nanoparticles on the surface. The configuration changes of the PANI chains resulting from the doping/dedoping procedure led to various loading amounts of Au nanoparticles. Reduction of 4-nitrophenol was chosen as the probe reaction to evaluate the catalytic activity of supported Au nanocatalysts. The catalytic results indicated that dedoping treatment of the PS/PANI supports provides stronger coordinative ability to metal nanoparticles as well as more -N= groups, which results in a better catalytic performance towards the reduction of 4-nitrophenol.

A novel one-pot aerobic oxidation/Knoevenagel condensation reaction system was developed employing a Cu(II)/amine bifunctional, basic metal–organic framework (MOF) as the catalyst. The sequential aerobic alcohol oxidation/Knoevenagel condensation reaction was efficiently promoted by the Cu3TATAT MOF catalyst in the absence of basic additives. The benzylidenemalononitrile product was produced in high yield and selectivity from an inexpensive benzyl alcohol starting material under an oxygen atmosphere. The role of the basic functionality was studied to demonstrate its role in the aerobic oxidation and Knoevenagel condensation reactions. The reaction progress was monitored in order to identify the reaction intermediate and follow the accumulation of the desired product. Lastly, results showed that the yield was not significantly compromised by the reuse of a batch of catalyst, even after more than five cycles.