Journal of Chemical Sciences最新文献

Cucurbit[n]urils (CB[n], n = 5–8) are the most important class of host molecules that are widely applied in various important applications. Until now, no sensitive sensor has been developed exclusively for detecting cucurbiturils. Here, we have utilized the supramolecular assembly of acriflavine and graphene oxide (ACF-GO) as a fluorescence sensor for the detection of cucurbituril family members such as CB[5], CB[6] and CB[7] with the discrimination of fluorescence intensities. Among them, CB[7] displayed the highest sensitivity, which can be detected as low as nano-molar concentration, and that allowed us to make a facile fluorescence method of detection for CB[7] and other CBs.

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Supramolecular assembly of acriflavine on the graphene oxide turn-off the fluorescence of acriflavine and upon interaction with cucurbit[7]uril, that released the acriflavine to the solution and turn-on the fluorescence, which allowed to detect the CB[7] to the lowest of nano-molar concentration.

This work delves into the utility of chromium’s X-ray fluorescence (XRF) lines for the analysis of chromite ores, employing a wavelength-dispersive XRF spectrometer. The CrLα_1,2 and CrLβ₁ fluorescence lines, despite not involving electronic transitions from valence to K-core shell, offer substantial insights into the valence state of chromium. This study examines these relatively unexplored but potentially valuable lines and compares them with the CrKβ series fluorescence lines. Intriguingly, our investigation reveals striking differences in the L-line fluorescence spectra between metallic chromium (Cr(0)), chromite ores (Fe, Mg)Cr₂O₄, and K₂Cr₂O₇. Chemical shifts and peak shapes emerge as key discriminators, surpassing the sensitivity of the CrKβ_1,3 lines. Notably, the chemical shifts of L-lines are amplified, showcasing a clear trend: Cr(III) exhibits a larger shift than Cr(VI), mirroring the pattern observed in the Kβ-lines. The fluorescence peak shapes of Lα_1,2 and Lβ₁ for metallic chromium and chromite ores (both have unpaired 3d-electrons) are similar, whereas those of K₂Cr₂O₇ differ considerably in peak shape, indicating that unpaired 3d-electrons influence these peaks. A linear relationship was found between the area under the curve ratio for Lα_1,2 and Lβ₁ and the valence state of chromium.

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Abstract

Due to the presence of a carboxyl group, coumarin-3-carboxylic acid can easily participate in C3-, and C4-functionalization, as well as cyclization reactions. The carboxyl moiety as a directing group enhances the reactivity of coumarins as dienophiles, which facilitates the participation of these scaffolds in the synthesis of various heterocycles. Hence, this review highlights the reports since 2010 on the contribution of coumarin-3-carboxylic acids in decarboxylative and cyclization reactions and discusses interesting reaction mechanisms.

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Coumarins are privileged O-heterocycles and appear in biologically active natural and medicinal products. The presence of carboxyl as a directing group allowed coumarin-3-carboxylic acid to participate in C3-, or C4-functionalization, and annulations. This compound has attracted extensive attention from chemists in the field of cross-coupling methodologies to provide functionalized structures.

Organic near-infrared (NIR) photothermal agents have tremendous potential in cancer therapy. Herein we report anovel NIR light responsive photothermal agent DDHT/F127 micelles, which has excellent photothermal properties and photostability, along with outstanding outcomes in cancer phototherapy.

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A novel donor-acceptor (D-A)-type organic photothermal material 5,18-dibutyl-5,18- dihydro-diquinoxaline[2,3-a:2',3'-c]-phenazine (DDHT) was encapsulated with Pluronic^® 127 (F127) material to form NIR light responsive photothermal agent DDHT/F127 micelles, which has excellent photothermal properties with photothermal conversion efficiency of 51.55% under 655 nm NIR laser irradiation, along with outstanding outcomes in cancer therapy.

The unique properties of hydroxyl-terminated polybutadiene (HTPB) make it suitable for use in various fields. Because it is impossible to use external factors to repair the damage caused by HTPB polymer in all places, it is very useful to create intrinsic self-healing properties. In this study, HTPB polymer became intrinsically self-healing during three stages of hydrobromination, amination, and the addition of 2-ureido-4-pyrimidinone groups. ATR and NMR analysis confirmed the formation of intermediates and the final self-healing compound. Also, DSC analysis showed that the glass transition temperature of the resin, which is its most important feature, has not changed. After self-healing HTPB was synthesized, this resin was mixed with isophorone diisocyanate and coated on a glass slide. The cured polyurethane coating was scratched, and an optical microscope monitored the healing process for 24 h. The corrosion test of metal plates confirmed the creation of self-healing properties in the resin. The places of scratches created on the control sample were rusted in the sodium chloride solution, while the plates with modified resin coating did not show this issue.

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HTPB polymer becomes intrinsically self-healing during three stages of hydrobromination, amination, and the addition of 2-ureido-4-pyrimidinone groups. These groups have a great tendency to form hydrogen bonds and give intrinsic self-healing properties to the resin. Self-healing HTPB can repair damage without the need for an external agent.

Microbial resistance is a growing threat to all of us worldwide. The need for rapid pharmaceutical solutions is a challenge for chemists. Computer-aided tools and molecular docking provide a speedy root for designing and investigating new metal-based drugs. Given this, the tris(hydroxamato)vanadium(III) complexes of composition [V(HL^1–2)₃] (I, II) (HL¹ (=) 4-NO₂C₆H₄CONHO⁻; HL² (=) 2-Cl-4-NO₂C₆H₃-CONHO⁻) have been synthesized by the reactions of VCl₃ with three equivalents of different potassium hydroxamate ligands in dry methanol. Elemental analyses, molar conductivity, molecular weight determination, magnetic moment measurements and IR, UV-Vis spectral studies, and mass spectrometry have characterized complexes. The magnetic moment and electronic spectra are consistent with the +3 oxidation state of vanadium. Based on physicochemical and spectral techniques, a distorted octahedral geometry around vanadium has been proposed for complexes. The electrochemical behavior of complexes studied by cyclic voltammetry has displayed a quasi-reversible V^IV/V^III redox couple. Molecular docking studies were conducted against the Klebsiella pneumoniae modA protein; complexes showed higher binding free energies than free ligands, displaying efficient binding at the protein groove. Therefore, the MIC method has evaluated free ligands and complexes for in vitro antimicrobial activity against bacteria and fungi.

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