Multifunctional Nanohybrids by Self-Assembly of Monodisperse Iron Oxide Nanoparticles and Nanolamellar MoS₂ Plates

Here, we report the synthesis, characterization, and properties of novel nanohybrids formed by self-assembly of negatively charged MoS₂ nanoplates and positively charged iron oxide nanoparticles (NPs) of two different sizes, 5.1 and 11.6 nm. Iron oxide NPs were functionalized with an amphiphilic random copolymer, quaternized poly­(2-(di­methyl­amino)­ethyl metacrylate-<i>co</i>-stearyl meta­crylate), synthesized for the first time using atom transfer radical polymerization. The influence of the MoS₂ fraction and the iron oxide NP size on the structure of the nanohybrids has been studied. Surprisingly, larger NPs retained a larger fraction of the copolymer, thus requiring more MoS₂ nanoplates for charge compensation. The nanohybrid based on 11.6 nm NPs was studied in oxidation of sulfide ions. This reaction could be used for removing the dangerous pollutant from wastewater and in the production of hydrogen from water using solar energy. We demonstrated a higher catalytic activity of the NP/MoS₂ nanohybrid than that of merely dispersed MoS₂ in catalytic oxidation of sulfide ions and facile magnetic recovery of the catalyst after the reaction

Fabrication of Magnetically Recoverable Catalysts Based on Mixtures of Pd and Iron Oxide Nanoparticles for Hydrogenation of Alkyne Alcohols

We report a novel method for development of magnetically recoverable catalysts prepared by thermal decomposition of palladium acetylacetonate in the presence of iron oxide nanoparticles (NPs). Depending on conditions, the reaction results either in a dispersed mixture of Pd and iron oxide NPs or in their aggregates. It was demonstrated that the Pd loading, reaction temperature, solvent, and iron oxide NP size and composition are crucial to control the reaction product including the degree of aggregation of Pd and iron oxide NPs, and the catalyst properties. The aggregation controlled by polarization and magnetic forces allows faster magnetic separation, yet the aggregate sizes do not exceed a few hundred nanometers, making them suitable for various catalytic applications. These NP mixtures were studied in a selective hydrogenation of 2-methyl-3-butyn-2-ol to 2-methyl-3-buten-2-ol, demonstrating clear differences in catalytic behavior depending on the catalyst structure. In addition, one of the catalysts was also tested in hydrogenation of 3-methyl-1-pentyn-3-ol and 3-methyl-1-nonyn-3-ol, indicating some specificity of the catalyst toward different alkyne alcohols

Polyphenylenepyridyl Dendrons with Functional Periphery and Focal Points: Syntheses and Applications

For the first time we report syntheses of a family of functional polyphenylenepyridyl dendrons with different generations and structures such as focal groups, periphery, and a combination of phenylene and pyridyl moieties in the dendron interior using a Diels–Alder approach and a divergent method. The dendron structure and composition were confirmed using NMR spectroscopy, MALDI-TOF mass spectrometry, FTIR, and elemental analysis. As a proof of concept that these dendrons can be successfully used for the development of nanocomposites, synthesis of iron oxide nanoparticles was carried out in the presence of thermally stable dendrons as capping molecules followed by formation of Pd NPs in the dendron shells. This resulted in magnetically recoverable catalysts exhibiting exceptional performance in selective hydrogenation of dimethylethynylcarbinol (DMEC) to dimethylvinylcarbinol (DMVC)