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Catalyst systems with high catalytic activity and sustainability are highly desirable. Here, we report a design for catalytic composites with a hierarchical structure in which polydopamine (PD), multi-metallic nanocatalysts and iron oxide nanoneedles are successively deposited on a magnetic core. PD layers with various thicknesses are coated onto the magnetic core and serve as a template by which to take up multi-metallic nanocatalysts such as Au, Ag and Pt nanoparticles. The iron oxide nanoneedles act as spacers, preventing the nanocomposite from aggregating and increasing the surface area of the composite. The distinctive structures of the controllable template, the multi-metallic catalysts and needle-like layers enable the rapid migration of reactive ionic species and enhance catalytic ability via the synergistic effect of the multi-metallic nanocatalysts and iron oxide nanoneedles. Moreover, due to the strong magnetic property of the catalytic nanocomposites, they can be easily recovered with an external magnet and reused. Our hierarchical nanocomposites for recyclable nanocatalysts provide a new design concept for highly efficient catalysts.

Hg 2+ ions can accumulate in the natural environment and in organisms, where they cause damage to the central nervous system. Therefore, the detection of Hg 2+ ions is essential for monitoring environmental contamination and human health. Herein, we demonstrate a simple method for tuning chemosensor signal ratios that significantly increased chemosensor selectivity for Hg 2+ detection. Selectivity tuning was accomplished for chemosensors of the type (diphosphine)Pt(dmit), bearing the two different terminal groups 1,2-bis(diphenylphosphino)ethane (dppe) and 1,2-bis[bis(pentafluorophenyl)phosphino]ethane) (dfppe) due to the modulation of specific intermolecular interactions between the dmit ligand and Hg 2+ ion. The structure exhibited a large pseudo-Stokes shift, which was advantageous for the internal reference signal and for eliminating potential artifacts. Straightforward chain-end manipulation enabled the tuning of chemosensor properties without additional chemical alterations. Based on these findings, we propose a new platform for improving the selectivity and sensitivity of colorimetric cation sensors. The results of this study will facilitate the designing of organic materials whose certain properties can be enhanced through precise control of the materials' chemical hybridization by simple functional end-group manipulation.

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Mg/Fe‐based magnetic bimetallic hydroxide nanosheets (MHNs) are synthesized by a simple molten salt method (MSM) in 1 min. The surface of the MHNs readily became hydrophobic following octadecyltrimethoxysilane treatment; the hydrophobic MHNs (HMHNs) are then coated onto a Cu mesh and a melamine (MF) sponge by the dip‐coating method for use in oil/water separation. The separation efficiencies of both the HMHN‐coated Cu mesh and MF sponge are greater than 99% for all types of oils, and these samples has significant fluxes and absorption capacities. The HMHN‐coated Cu mesh show outstanding reusability and chemical durability in harsh environments, such as acidic, alkaline and saline solutions, and exhibit excellent oil separation efficiencies for water‐in‐oil emulsions. Moreover, the HMHN powder itself quickly absorb highly viscous oil spills floating on the surfaces of both water and oil stabilized in water, and it can be easily recovered with an external magnet. Due to the economical synthetic process and the variety of techniques applicable to selective oil separation, these MHNs show great potential in the field of oily wastewater treatment.

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Ferrocenyl chalcones (Fc-C(O)CH=CH-Ar: Fc-Ar) with mono-and di-1-naphthalenyl moieties (Fc-1Naph and Fc-d1Naph) were prepared and spectroscopically characterized. The enone bridge was in the s-cis conformation and the π-electrons on the C=C bond were further delocalized on the bridge. The naphthalenyl moiety deviates greatly from the enone-Cp plane by 26.9(1) o . Cyclic voltammetry measurements for Fc-1Naph exhibit one reversible cycle for the redox of the ferrocenyl moiety at a lower potential, and one irreversible oxidation peak at the higher potential region. For Fc-d1Naph, the cyclic voltammogram is more featureless. Fluorescence properties for both compounds are active in polar solvents with λ em = 500 nm (EtOH) and λ em = 512 nm (MeOH) for Fc-1Naph and λ em = 496 nm (EtOH) and λ em = 508 nm (MeOH) for Fc-d1Naph. The intensity of Fc-d1Naph is more than twice than that of Fc-1Naph. The fluorescence properties for both compounds are inactive in the less polar solvents such as CH 3 CN, CH 2 Cl 2 and CHCl 3 .