Surprisingly High Selectivity and High Affinity in Mercury Recognition by H‑Bonded Cavity-Containing Aromatic Foldarands

In the absence of macrocyclic ring constraints, few synthetic systems, possessing a mostly solvent-independent well-folded conformation that is predisposed for highly selective and high affinity recognition of metal ions, have been demonstrated. We report here such a unique class of conformationally robust modularly tunable folding molecules termed foldarands that can recognize Hg²⁺ ions surprisingly well over 22 other metal ions. Despite the lack of sulfur atoms and having only oxygen-donor atoms in its structure, the best foldarand molecule, i.e., tetramer <b>4</b>, exhibits a selectivity factor of at least 19 in differentiating the most tightly bound Hg²⁺ ion from all other metal ions, and a binding capacity that is ≥18 times that of thio-crown ethers. These two noteworthy binding characters make possible low level removal of Hg²⁺ ions. With a [<b>4</b>]:[Hg²⁺] molar ratio of 5:1 and a single biphasic solvent extraction, the concentration of Hg²⁺ ions could be reduced drastically by 98% (from 200 to 4 ppb) in pure water. <b>4</b> could also effect a highly efficient reduction in mercury content by 98% (from 500 to 10 ppb) in artificial groundwater via multiple successive extractions with an overall consumption of <b>4</b> being 9:1 in terms of [<b>4</b>]:[Hg²⁺] molar ratio

Surprisingly High Selectivity and High Affinity in Mercury Recognition by H‑Bonded Cavity-Containing Aromatic Foldarands

In the absence of macrocyclic ring constraints, few synthetic systems, possessing a mostly solvent-independent well-folded conformation that is predisposed for highly selective and high affinity recognition of metal ions, have been demonstrated. We report here such a unique class of conformationally robust modularly tunable folding molecules termed foldarands that can recognize Hg²⁺ ions surprisingly well over 22 other metal ions. Despite the lack of sulfur atoms and having only oxygen-donor atoms in its structure, the best foldarand molecule, i.e., tetramer <b>4</b>, exhibits a selectivity factor of at least 19 in differentiating the most tightly bound Hg²⁺ ion from all other metal ions, and a binding capacity that is ≥18 times that of thio-crown ethers. These two noteworthy binding characters make possible low level removal of Hg²⁺ ions. With a [<b>4</b>]:[Hg²⁺] molar ratio of 5:1 and a single biphasic solvent extraction, the concentration of Hg²⁺ ions could be reduced drastically by 98% (from 200 to 4 ppb) in pure water. <b>4</b> could also effect a highly efficient reduction in mercury content by 98% (from 500 to 10 ppb) in artificial groundwater via multiple successive extractions with an overall consumption of <b>4</b> being 9:1 in terms of [<b>4</b>]:[Hg²⁺] molar ratio

One-Pot Synthesis of Strained Macrocyclic Pyridone Hexamers and Their High Selectivity toward Cu²⁺ Recognition

The removal of Cu²⁺ ions is relevant to environmental pollution control and neurodegenerative disease treatment. A novel family of strained macrocyclic pyridone hexamers, which exhibit highly selective recognition of Cu²⁺ ions and reduce copper content in artificial seawater by 97% at a very low [host]:[CuCl₂] molar ratio of 2:1, is documented

Revealing Surface States in In-Doped SnTe Nanoplates with Low Bulk Mobility

Indium (In) doping in topological crystalline insulator SnTe induces superconductivity, making In-doped SnTe a candidate for a topological superconductor. SnTe nanostructures offer well-defined nanoscale morphology and high surface-to-volume ratios to enhance surface effects. Here, we study In-doped SnTe nanoplates, In_<i>x</i>Sn_1–<i>x</i>Te, with <i>x</i> ranging from 0 to 0.1 and show they superconduct. More importantly, we show that In doping reduces the bulk mobility of In_<i>x</i>Sn_1–<i>x</i>Te such that the surface states are revealed in magnetotransport despite the high bulk carrier density. This is manifested by two-dimensional linear magnetoresistance in high magnetic fields, which is independent of temperature up to 10 K. Aging experiments show that the linear magnetoresistance is sensitive to ambient conditions, further confirming its surface origin. We also show that the weak antilocalization observed in In_<i>x</i>Sn_1–<i>x</i>Te nanoplates is a bulk effect. Thus, we show that nanostructures and reducing the bulk mobility are effective strategies to reveal the surface states and test for topological superconductors

Intense Photocurrent from Mo-Doped TiO₂ Film with Depletion Layer Array

A novel bilayer structure of TiO₂ film was found capable of yielding fairly strong photocurrent under visible light. The base layer was lightly doped with Mo and then etched by reactive ion beam, and was finally covered by an undoped TiO₂ surface layer. Because of Fermi level drop at the interface of the trenches, such a deposition–etching–redeposition process implanted an array of depletion layer into TiO₂ film successfully. Microstructures, crystallite parameters, and the absorption property were investigated with scanning electron microscope, atomic force microscopy, X-ray diffraction, and ultraviolet–visible spectroscopy in order. Photocurrent density was collected on an electrochemical workstation under visible light. The results indicate that carrier collection probability near depletion layer was enhanced significantly owing to high parallel diffusivity. Under visible light, current density demonstrates a marked increase as etching depth grows. At an etching depth around 660 nm, photocurrent density achieved is 56 times larger than TiO₂ film. Depletion layer at vertical trench edges may have a much bigger universal value than anticipated for various doping cases of wide-bandgap films

SCFAs concentration analyzed by gas chromatography (GC).

<p>a, acetate; b, butyrate; c, propionate. Data with asterisk were significantly different (<i>p</i><0.05).</p

The comparison of TNF-α during the period of experiment.

<p>Data with asterisk were significantly different (p<0.05).</p

The result of qPCR for butyryl CoA transferase (BCoAT) and formyltetrahydrofolate synthetase (FTHFS) genes.

<p>Values were the percentage of BCoAT copies/Bacteria copies and FTHFS copies/Bacteria copies.</p

Representative HE images that were used for mucus layer thickness measurements (n = 4).

<p>1 from the control, 2 from 20⁻¹ Cd, 3 from 100 mg kg⁻¹ Cd. IM, inner mucus layer, (A). Thickness of the mucus layer measured by histological analyses after HE staining. Data with asterisk were significantly different (<i>p</i><0.05), (B).</p

Comparison of the diameter of the colony between control and Cd treatments during the period of incubation.

<p>Comparison of the diameter of the colony between control and Cd treatments during the period of incubation.</p