Journal of Chemical Sciences最新文献

The increasing demand for neodymium (III) and samarium (III) due to their extensive high-tech applications has drawn much attention to their recovery. In this work, the copper-based metal-organic framework HKUST-1 was prepared and used for the adsorption of neodymium (III) and samarium (III) in the media of an aqueous solution. The maximum adsorption capacity of the material for neodymium (III) and samarium (III) was 284.11 and 503.45 mg g⁻¹ at a pH of 5.5, respectively. The adsorption removal rate could achieve nearly 100% at the solid-to-liquid ratio of 1.0 g L⁻¹, which is relatively excellent among such adsorbents used for rare earth elements uptake. The mechanism and reversibility of neodymium (III) and samarium (III) adsorption were systematically investigated by X-ray diffraction, Fourier transforms infrared spectroscopy, Raman spectra, and X-ray photoelectron spectroscopy, suggesting that the mechanism for the adsorption was ion exchange and complexation between trivalent rare-earth ions and the oxygen atom in the hydroxyl group. The reason behind the material displaying a more robust affinity for samarium (III) may be caused by the energy difference between fⁿ and fⁿ⁺¹ states of samarium (III) was larger than that of neodymium (III), thus forming stronger covalent bonding.

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HKUST-1 exhibited high adsorption capacity towards Nd (III) and Sm (III). The reason behind the material displaying a more robust affinity for Sm(III) was caused by that the energy difference between fⁿ and fⁿ⁺¹ states of Sm(III) was larger than that of Nd(III), thus forming stronger covalent bonding.

A simple ion-exchange method is used to prepare Mn and Co-supported TNU-9 denitration catalyst for NH₃-SCR. The denitration activity and H₂O/SO₂ resistance performance of the catalyst are systematically studied. The denitration activity test exhibits that the NO_x removal rate of Mn-Co/TNU-9 is higher than that of Mn/TNU-9 and Co/TNU-9, the NO_x removal rate is greater than 90% and the N₂ selectivity is greater than 99% in the range of 150 ~ 450 °C. It is because the redox cycle of Mn⁴⁺ + Co²⁺ ↔ Mn³⁺ + Co³⁺ improves the redox performance of the catalyst, which is conducive to the conduction of electrons, and then accelerates the oxidation of NO to NO₂ to produce a "fast SCR" reaction, and finally optimizes the overall SCR performance. Furthermore, the change is not significant for the catalytic activity over Mn-Co/TNU-9 in the presence of water. However, the sulfur resistance is poor at low temperatures due to the presence of ammonium bisulfate. It also has excellent catalytic stability. Therefore, supported TNU-9 catalysts will have a good development prospect in denitrification.

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Mn-Co co-doped TNU-9 catalyst was successfully synthesized by simple ion exchange method and applied in the NH₃-SCR. The results show that Mn-Co/TNU-9 catalyst has an excellent wide activity window in a wide temperature range of 150-450°C (NO_x conversion over 90%), which is because Mn+Co²⁺↔Mn+Co improves the redox performance and facilitates the electron transfer, which further accelerates the oxidation of NO into NO₂ that could result in the “Fast SCR” reaction. The synergistic effect between Mn and Co bimetallic can also improve activity. Moreover, Mn-Co/TNU-9 has very good catalytic stability.

Controlling the shape of a metal nanostructure allows to control its properties, yet the processes that induce solution-phase anisotropic growth of metal nanostructures are still a mystery. Though the iodide ion is well-known as a shape-directing agent, the study emphasizes the role of alkylamine in the shape-shifting of 1D Cu nanowires to 2D Cu nanoplates in conjunction with the iodide source. The role of iodide and Cu precursor sources for the production of 2D microplates is also highlighted in this study.

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In the presence of alkylamine, iodide ions derived from ionic sources (HI and KI) create 2D microplates, whereas molecular iodine produces wafer-like Cu nanostructures. Cu microplates, on the other hand, cannot be made from CuI in the presence of alkylamine, demonstrating the importance of the precursor's binding strength in the production of Cu microplates.

In this paper, a highly efficient and sustainable synthesis of triarylmethanes through the dehydrative coupling of p-quinols with diaryl carbinols is presented. The catalyst involved in this protocol is in situ generated superacid BF₃–H₂O from BF₃–OEt₂. Therefore, moisture has been used as an efficient initiator in this reaction system. A variety of diaryl carbinols and p-quinols have been investigated and found to be compatible to give the triarylmethanes in yields up to 96%.

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A high-efficiency adsorbent ZIF-8 was successfully prepared in a microemulsion system provided by an ionic liquid, which showed excellent potential for removing phosphate from water. The properties of the adsorbents were determined by several characterization methods, such as X-ray diffraction (XRD), infrared spectroscopy (FTIR) and Brunauere-Emmette-Teller (BET) et al. The results confirmed that ZIF-8 prepared in the ionic liquid microemulsion (ZIF-8-ILM) has a smaller particle size compared with that prepared in an aqueous solution. Moreover, the ZIF-8-ILM holds a high BET specific surface area and pore volume, as well as the textural meso- and macro-porosities formed by inter-particle voids. Based on these traits, the ZIF-8-ILM exhibit excellent adsorption capacity for phosphate, as evidenced by a maximum adsorption capacity of 178.99 mg/g was obtained. In addition, the capture of phosphate on ZIF-8-ILM was quite quickly and reached equilibrium within 60 min.

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A high-efficiency adsorbent ZIF-8 was successfully prepared in a microemulsion system provided by an ionic liquid. The ZIF-8 materials prepared not only had high BET specific surface area and pore volume but also exhibited hierarchical pore structure, which showed excellent potential for removing phosphate from water.

Impressive rate of solar water oxidation to molecular oxygen (O₂) has been demonstrated on nanorods (NRs) of Ce_0.9Ti_0.1O₂ (CT-NR) and Au-deposited CT-NR (Au-CT-NR) photocatalysts with a sacrificial agent (Fe³⁺) and in plain water in one sun condition, direct sunlight and with λ ≥ 455 nm. Probably the highest O₂ yield of 11 mmol/h.g was observed with Au-CT-NR thin film in plain water in direct sunlight, with no sacrificial agent or applied potential. Photoelectrochemical measurements demonstrate a marked reduction in oxidation onset potential of Au-CT-NR by 150 mV with stable photocurrent (0.75 mA/cm²), compared to CT-NR (0.23 mA/cm²), indicating the operative of plasmon-induced resonant energy transfer (PIRET) process. Effective electron quenching by nanogold and hence low recombination in the depletion region is a critical step for the observation of a high rate of oxygen evolution. In addition to this, a predominant change in the nature of the valence band from O-2p dominated on CeO₂ to Ce-4f dominated with CT-NR (due to Ti⁴⁺ introduction in CeO₂), the efficient light absorption of photocatalysts in thin-film form, functional and effective PIRET process, and facile E_F alignment, enhances the oxygen evolution with Au-CT-NR in direct sunlight and make it highly sustainable. A possible mechanism of water oxidation is proposed from the observed experimental findings.

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Extraordinary water oxidation capacity to O₂ in sunlight was achieved with a thin-film form of Au-CeTiO₂-NR by efficient light absorption followed by effective electron trapping in gold. This minimizes charge recombination and hence minority carriers were efficiently utilized. Reduction in overpotential, Fermi level equilibration and PIRET process due to nano-gold significantly improve the water oxidation capacity in a sustainable manner.

Here, we have demonstrated an easy and efficient synthetic route for the synthesis of the flavo-peptide conjugates as model for the naturally occurring covalently linked flavoenzymes. A judicially functionalized flavin analogue was used for the coupling reaction with the pre-synthesized peptidic motifs using solution-phase chemistry. Representative examples using mono-, di- and tripeptides were reported to couple with the C7-position of the flavin moiety to showcase the generic nature of the synthetic strategy. Further photophysical investigation including quantum yield measurements, concentration-dependent studies and fluorescence quenching experiments reveal the intramolecular nature of the charge transport process in cases where tyrosine is present, similar to that found in the natural counterpart.

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This manuscript discusses a simple/efficient approach for the synthesis of flavopeptide conjugates as a true model for covalently-liked-flavoenzymes. Coupling reaction between the suitably functionalized flavin moiety and the pre-synthesized peptide entities was envisaged and undertaken to prove the generality of the approach. Further photophysical investigation including quantum yield measurements, concentration-dependent studies and fluorescence quenching experiments reveal the intramolecular nature of the charge transport process in cases where tyrosine is present, similar to that found in the natural counterpart. Such a synthetic flavopeptide model may provide a further investigation to provide an insight into the corresponding biological phenomenon.

The mechanism of insertion reaction between phosphenium cation and phosphindene with oxirane has been investigated theoretically to better understand the reactivity for the valence isoelectronic of carbene. Phosphenium cation acts as an electrophilic reagent and accepts σ electrons of oxirane to form a complex in the first combination step. The greater the positive charge on phosphorus in phosphenium cation, the more stable the formed complex is. The introduction of substituents will decrease the positive charge on phosphorus in phosphenium cation. The order of positive charge on phosphorus is HP⁺-F > HP⁺-OH > HP⁺-NH₂, which is consistent with their Lewis acidities. The complex transforms to a four-membered ring product via a transition state in the second insertion step. The product is more stable than the complex due to the decrease of ring extension.

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Phosphenium cation acts as an electrophilic reagent and accepts σ electrons of oxygen in oxirane to form a four-membered ring product. The introduction of substituents will decrease the positive charge on phosphorus in phosphenium cation, which reduced the stability of the products.

Exploring the new therapeutic indications of known drugs for treating COVID-19, popularly known as drug repurposing, is emerging as a pragmatic approach especially owing to the mounting pressure to control the pandemic. Targeting multiple targets with a single drug by employing drug repurposing known as the polypharmacology approach may be an optimised strategy for the development of effective therapeutics. In this study, virtual screening has been carried out on seven popular SARS-CoV-2 targets (3CL^pro, PL^pro, RdRp (NSP12), NSP13, NSP14, NSP15, and NSP16). A total of 4015 approved drugs were screened against these targets. Four drugs namely venetoclax, tirilazad, acetyldigitoxin, and ledipasvir have been selected based on the docking score, ability to interact with four or more targets and having a reasonably good number of interactions with key residues in the targets. The MD simulations and MM-PBSA studies showed reasonable stability of protein-drug complexes and sustainability of key interactions between the drugs with their respective targets throughout the course of MD simulations. The identified four drug molecules were also compared with the known drugs namely elbasvir and nafamostat. While the study has provided a detailed account of the chosen protein-drug complexes, it has explored the nature of seven important targets of SARS-CoV-2 by evaluating the protein-drug complexation process in great detail.

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Drug repurposing strategy against SARS-CoV2 drug targets. Computational analysis was performed to identify repurposable approved drug candidates against SARS-CoV2 using approaches such as virtual screening, molecular dynamics simulation and MM-PBSA calculations. Four drugs namely venetoclax, tirilazad, acetyldigitoxin, and ledipasvir have been selected as potential candidates.