Thiacalix[4]arene receptors with two urea moieties exhibited a high affinity towards all of the selected anions.

Heteroditopic hexahomotrioxacalix[3]arene receptors that are capable of binding an anion and a cation simultaneously in a cooperative fashion were synthesized. The structure of one of the triamide derivatives was confirmed by single-crystal X-ray diffraction. The binding of alkali metals at the lower rim, and the binding of anions (chloride, bromide) at the upper rim, has been investigated by using (1)H NMR titration experiments. Alkali metal binding at the lower rim controls the calix cavity. Li(+)-ion binding to the lower rim can improve the binding ability of anions at the upper rim amide moiety by a factor of 15, thus suggesting a strong positive allosteric effect for anion recognition. However, when a Na(+) cation is bound to the ionophoric site on the lower rim, the calix cavity is changed from a "flattened cone" to a more-upright form, which is favored for intramolecular hydrogen bonding between the neighboring NH and C=O groups; this change can block the inclusion of anions onto the amide moiety at the upper rim, which strongly suggests a negative allosteric effect of Na(+)-ion binding, which controls the cooperative recognition system.

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In this research, N-butyl-pyridinium tetrafluoroborate ([BPy][BF 4 ]) ionic liquid (IL) was synthesized and characterized by 1 H-NMR, 13 C-NMR, and FT-IR spectroscopy. The synthesized ionic liquid was employed as an extractive agent for the removal of dibenzothiophene (DBT), a typical organosulfur pollutant from the organic medium. The effect of extractive desulfurization on a model fuel with DBT was investigated. The impact of operating parameters, i.e., temperature, extraction time, IL-to-fuel ratio, and fuel to oxidizing agent ratio, on the extraction efficiency was investigated. It was observed that the IL to model fuel ratio and the H 2 O 2 dosage have significant effects on desulfurization efficiency. An 89.49% DBT removal efficiency was obtained at a temperature of 30 °C after 35 min of extraction when the volume ratio of IL:model fuel:H 2 O 2 was 1:1:0.04. A density functional theory (DFT) study was carried out to investigate the interactions between the IL and the sulfur-containing compounds DBT/ DBTO 2 .

Detecting the human immunodeficiency virus (HIV) is difficult because the virus is prone to mutations and is in low concentrations in the body. Inside the HIV virion are two well characterized single stranded (ss) RNA molecules (viral genome) that feature both variable regions and regions that are conserved under virus mutation. In this work, microcantilever sensors have been employed as potential HIV detectors by targeting a conserved sequence of the viral genome by attempting to detect target ssDNA and ssRNA molecules that are significantly longer than the ssDNA molecules functionalized on the cantilever.

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A carbon quantum dot-based chitosan hydrogel was prepared in this work as a fluorescence sensor for the selective sensing of Hg 2+ ions. Among the eight tested metal ions, the prepared hydrogel exhibited remarkable sensing selectivity and sensitivity toward Hg 2+ . The results demonstrated that a prominent fluorescence quenching at 450 nm was observed in the presence of Hg 2+ with a linear response range of 0–100.0 nM and an estimated limit of detection of 9.07 nM. The as-prepared hydrogel demonstrates pH-dependent fluorescence intensity and sensitivity. The highest fluorescence intensity and sensitivity were obtained under pH 5.0. The excellent sensing selectivity could be attributed to a strong interaction between the hydrogel film and Hg 2+ ions to form complexes, which provokes an effective electron transfer for fluorescence quenching. Results from density functional theory (DFT) calculation confirm that the interaction energies (ΔIE) of the hydrogel with three toxic metal ions (Hg 2+ , Cd 2+ , and Pb 2+ ) are in the following order: Hg 2+ > Cd 2+ > Pb 2+ .

To create your abstract, type over the instructions in the template box below. Fonts or abstract dimensions should not be changed or altered.Synthesis, crystal structure and complexation behaviour study of an efficient Cu 2+ ratiometric fluorescent chemosensor based on thiacalix[4]arene