Chemistry - An Asian Journal最新文献

A series of donor-acceptor (D-A) terpyridine derivatives with various intramolecular charge transfer interactions have been successfully synthesized bearing phenyl, methoxyphenyl, N-butyldiphenylamine (DPA), and triphenylamine (TPA) as electron-donors and terpyridine (TPY), 2,6-di(pyrazin-2-yl)pyridine (PYDPZ), and N,N-dimethylated PYDPZ (PYDPZ-2CH3) as electron acceptors. Upon the introduction of pyrazine rings instead of pyridine ones and further selective N,N'-dimethylation, the intramolecular D-A interactions are significantly enhanced, resulting in the remarkable reduced intramolecular charge transfer (ICT) transitions and quenched PL emissions in CH2Cl2 solution. However, their ICT emissions are clearly recovered upon adding Zn2+. Especially, for double positively charged compound 12, the Zn2+-induced "turn-on" green emission (λmax, em = 518 nm, Φ = 0.24) with excellent sensitivity (I/I0 = 77) and selectivity (IZn/ICd = 23) is detected. Under the optimized experimental condition (EtOH-H2O (9:1, v/v), containing 0.05 M HEPES buffer (pH = 7.4)), this probe is used to quantitative determination of Zn2+ in a water sample with an average recovery of 97.5%. Furthermore, the probe is applied to imaging of Zn2+ ions in HeLa cells and its mechanism is confirmed by the molecular dynamics simulation, in which lower coulomb potential for membrane surface adsorption and energy barrier for membrane translocation can be found.

Solvent plays an important role in many chemical reactions. The C-H activation has been one of the most powerful tools in organic synthesis. These reactions are often assisted by solvents which not only provide a medium for the chemical reactions but also facilitate reaching to the product stage. The solvent helps the reaction profile both chemically and energetically to reach the targeted product. Organic transformations via C-H activation from the solvent assistance perspective has been discussed in this review. Various solvents such as tetrahydrofuran (THF), MeCN, dichloromethane (DCM), dimethoxyethane (DME), 1,2-dichloroethane (1,2-DCE), dimethylformamide (DMF), dimethylsulfoxide (DMSO), isopropyl nitrile (ⁱPrCN), 1,4-dioxane, AcOH, trifluoroacetic acid (TFA), Ac₂O, PhCF₃, chloroform (CHCl₃), H₂O, N-methylpyrrolidone (NMP), acetone, methyl tert-butyl ether (MTBE), toluene, p-xylene, alcohols, MeOH, 1,1,1-trifluoroethanol (TFE), 1,1,1,3,3,3-hexafluoroisopropanol (HFIP), tert-amyl alcohol and their roles are discussed. The exclusive role of the solvent in various transformations has been deliberated by highlighting the substrate scope, along with the proposed mechanisms. For easy classification, the review has been divided into three parts: (i) solvent-switched divergent C-H activation; (ii) C-H bond activation with solvent as the coupling reagent, and (iii) C-H activation with solvent caging and solvent-assisted electron donor acceptor (EDA) complex formation and autocatalysis.

Developing effective, cost-efficient, and eco-friendly energy storage solutions is crucial for sustainable building structures. Red mud, a waste material, was used as the electrolyte and separator in supercapacitors, alongside activated carbon derived from jute sticks coated on steel mesh electrodes. Tests on RM-enhanced supercapacitors showed that 20% by weight of RM was the best amount. This increased the modulus of elasticity by 33%, the tensile strength by 3%, and the compressive strength by 10%. Durability was largely unaffected, with minimal additional water absorption and slight shrinkage variation. The supercapacitor cell had an extended cell potential of 1.5 V and a maximum specific capacitance of 62.3 F g-1 at 0.4 A g-1, as shown by electrochemical tests. This improved energy density to 19.5 Wh kg-1, with a power density of 301.8 W kg-1 at 0.4 A g-1 and a maximum power density of 605.8 W kg-1 at 0.8 A g-1. The cell retained 77% of its initial capacitance after 450 continuous GCD cycles, demonstrating notable stability. This stability is due to the solid electrolyte and the synergy between JC and RM, indicating promising advancements for future energy storage devices.

An efficient silver-mediated allylation of aryl alkenes is described, which provides a variety of skipped 1,4-dienes.Without the need for other traditional transition metals or gold, this AgOTf-mediated allylation proceeds smoothly with high regio- and stereoselectivity. Mechanistic and computational studies suggest that this silver-mediated allylation takes place via a Friedel-Crafts-type pathway of aryl alkenes to the silver-activated allyl acetates.

A series of compounds with the general formula A2MB2O6 (A = Zn, Ba, Pb; B = Pb, Ba, Zn, Cu) related to the kotoite structure has been prepared employing high-temperature solid state methods. The substitution of transition elements in place of Zn2+ ions resulted in colored compounds. The optical absorption spectra could be explained based on Tanabe-Sugano diagram and allowed d-d transitions. Dielectric studies on Ba2ZnB2O6, (Ba1.5Pb0.5)ZnB2O6, PbZn2B2O6, Pb1.5Zn1.5B2O6, BaZn2B2O6 and Pb2CuB2O6 at room temperature indicate reasonable values at low frequencies, which decrease on increasing frequencies. Magnetic study of synthesized single-phase compounds BaZnCoB2O6 and Pb2CuB2O6 have been performed. The substitution of Eu3+, Tb3+ and Tm3+ in place of Ba2+ in Ba2ZnB2O6, gives rise to the expected emission of red, green and blue colors. Suitable modifications of the different phosphors in Ba2ZnB2O6, resulted in white-light emission in Ba2ZnB2O6. The Pb2CuB2O6 compound was found to be a good catalyst in the ipso-hydroxylation of arylboronic acids.

The microwave-assisted methodology is now extended and fine-tuned for the synthesis of mixed-ligand europium complexes with an average reaction time of 12 min. Overall, 14 different complexes were synthesized to improve luminescence using our previously proposed strategy to boost luminescence through ligand diversification, specifically by applying it to quaternary europium complexes with at least one DBM (1,3-diphenylpropane-1,3-dionate) ligand. DBM is a strong absorbant of UV radiation that can dissipate energy through nonradiative channels; thus, it is a useful molecular scaffold for sunblockers and cosmetics. Accordingly, the following luminescent tetrakis and quaternary complexes were prepared: K[Eu(DBM)₄], K[Eu(β)₄], K[Eu(DBM)₃(β)], K[Eu(DBM)₂(β)₂], K[Eu(DBM)₂(β)(β')], and the fully mixed complex K[Eu(DBM)(BTFA)(TTA)(HFAC)], where β can be either BTFA (4,4,4-trifluoro-1-phenylbutane-1,3-dionate), TTA (4,4,4-trifluoro-1-(2-thienyl)butane-1,3-dionate), or HFAC (1,1,1,5,5,5-hexafluoropentane-2,4-dionate). For all the complexes, luminescence experiments were performed in chloroform and acetone solutions. Our findings confirm that mixed-ligand complexes exhibit superior quantum efficiencies compared to the average of their homoleptic counterparts. The presence of DBM in the complexes tends to dramatically increase the nonradiative decay rates of the solutions. Finally, we present formulae that provide a detailed understanding of the distinctive roles of each ligand and their relevant interactions in luminescence.

Two novel BODIPY dyes, BOC3 and BC12, were synthesized with variable alkyl chains at terminal amide functional units. BC12, featuring a longer alkyl chain (-C12H25), formed a gel compared to BOC3, which has a shorter alkyl chain (-CH2OCH3), due to supra molecular self-assembly in film. Both dyes exhibited absorption peaks around 530 nm in the visible region, with a red shift of about 30 nm in the film state, essential for organic electronic applications. Concentration variation studies revealed π-π stacking/aggregates in the solid state causing red shifts in absorption and emission. BC12 exhibited more significant red shifts in film compared to its solution state due to supra molecular self-assembly. Electronic structure analysis using density functional theories (BMK and O3LYP) showed better correlation with absorption using the O3LYP method. Both dyes displayed quasi-irreversible oxidation and reduction couples with suitable HOMO (5.46 eV) and LUMO (3.32 eV) energy levels for organic electronic applications. Transient photoluminescence studies indicated a longer lifetime for BC12 (5.28 ns) than BOC3 (4.50 ns), suggesting π-π aggregation and supra molecular self-assembly. BC12's gelation, attributed to its long alkyl chain and two-dimensional motifs of the BODIPY core, forms spherical-shaped nano networks.

Liver fibrosis, mainly arising from chronic viral or metabolic liver diseases, is a significant global health concern. There is currently only one FDA-approved drug (Resmetirom) in the market to combat liver fibrosis. Both galectin-3 and epidermal growth factor receptor (EGFR) play important roles in liver fibrosis, while galectin-3 may interact with EGFR. Galectin-3 inhibitors, typically lactose or galactose derivatives may inhibit liver fibrosis. We hypothesized that targeting both galectin-3 and EGFR may have better effect against liver fibrosis. Here, EGFR inhibitor erlotinib was used in a series of designed galectin-3 inhibitors after hybridization with the pharmacophore structure in reported galectin-3 inhibitors to impede hepatic stellate cells (HSCs) activation by a typical method of click chemistry. Bioactivity test results showed that compound 29 suppressed TGF-β-induced upregulation of fibrotic markers (α-SMA, fibronectin-1, and collagen I). The preferred compound 29 displayed better binding to galectin-3 (KD = 52.29 μM) and EGFR protein (KD = 3.31 μM) by SPR assay. Further docking studies were performed to clarify the possible binding mode of compound 29 with galectin-3 and EGFR. Taken together, these results suggested that compound 29 could be a potential dual galectin-3 and EGFR inhibitor as leading compound for anti-liver fibrosis new drug development.

A computational approach to directly estimate the relative acidity of a given Lewis acid is presented. This approach is based on the strength of the π-conjugation in trans-crotonaldehyde-Lewis acid complexes, the species used in the well-known Childs' Lewis acidity scale. It is found that the π-conjugative strength values given by the Energy Decomposition Analysis - Natural Orbital for Chemical Valence method strongly correlate not only with the variation of the bond lengths in the system, which are greatly affected by the nature of the Lewis acid, but also with the downfield shifts experienced by the different nuclei of the conjugated system upon binding to the Lewis acid. These strong correlations indicate that the (easy-to-compute) π-conjugation energies can be used as an alternative Lewis acidity scale.

Doped ceria-supported cobalt nanoparticles are highly effective catalysts for the water-gas shift (WGS) reaction, converting carbon monoxide (CO) into carbon dioxide (CO₂) while simultaneously generating hydrogen (H₂) from water. The doped ceria enhances oxygen mobility and redox properties, improving the activity and stability of cobalt nanoparticles. This synergy accelerates CO conversion, making it a promising approach for hydrogen production and CO removal in industrial applications. More details can be found in article number e202400752 by Deshetti Jampaiah, Suresh K. Bhargava, and co-workers.