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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.

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.

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