Journal of Chemical Sciences最新文献

In this work, sulfonic acid group modified ZSM-5 (SFZ-x, x presents the weight percentage of mercaptopropyltrimethoxysilane during preparation) has been prepared by introducing sulfydryl on ZSM-5 and then oxidizing them into the sulfonic acid group. The obtained samples were characterized by XRD, N₂ adsorption/desorption, FTIR, and SEM and studied the catalytic performance in the hydration of cyclohexene to produce cyclohexanol. The characterization results showed that with the introduction of -SO₃H, the crystallinity of SFZ-15 decreased slightly, and the Brønsted acid sites obviously increased, while the pore structure was almost unchanged inside the ZSM-5 zeolites. Therefore, SFZ-15 exhibits better catalytic performance in the hydration of cyclohexene to produce cyclohexanol compared to commercial ZSM-5. Furthermore, this SFZ-15 catalyst kept the conversion of cyclohexene over 12% and the selectivity of cyclohexanol over 99% even after five runs, demonstrating the benefit of –SO₃H functionalization on the activity improvement of traditional ZSM-5 catalyst.

Graphical abstract

The sulfonic acid group modified ZSM-5 zeolite has been prepared by introducing sulfydryl on ZSM-5 and then oxidizing them into the sulfonic acid group. The prepared catalyst exhibits excellent catalytic performance in the hydration of cyclohexene to produce cyclohexanol.

Topological descriptors are quantitative parameters that correlate the attributes of molecular structures, providing insights into their chemical properties and behavior. With the increasing significance of dendrimers in drug design, driven by advancements in technology, our study focuses on the topological analysis of non-conjugated ethylene oxide cored dendrimer decorated with tetraphenylethylene. We derive key degree-based descriptors, including degree, neighborhood degree, and reverse degree, using the novel M-polynomial approach. This innovative method not only facilitates the calculation of these descriptors but also has the potential to generate additional descriptors. Our results demonstrate the applicability of these descriptors in Quantitative Structure-Property Relationship (QSPR) and Quantitative Structure-Activity Relationship (QSAR) models, predicting properties across different generations of the dendrimer. Furthermore, a graphical comparison is provided to enhance the understanding and analysis of the derived descriptors. This work represents a significant step forward in the mathematical modeling of dendritic structures, offering new tools for researchers in the field of chemical graph theory and molecular chemistry.

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This study presents a computational framework for predicting molecular properties without experimental research. Molecular descriptors, including degree based and entropy measures, are utilized in QSPR analysis. Statistical tools and regression models facilitate property prediction, offering valuable insights into molecular structures and their characteristics through topological descriptors.

We developed a mild protocol for the formal insertion of diazo compounds into the C–H bond of electron deficient 1,3-dicarbonyl compounds. The Lewis acid-catalyzed reaction proceeds through protonation of the diazo compound followed by nucleophilic substitution of diazo-N₂ with dicarbonyl substrate. The reaction is notable for its mild conditions, wide substrate scope and high yields of the products.

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A facile and efficient synthesis of polysubstituted pyridin-2(1H)-ones has been developed via a formal [4+2] annulation of readily available α-functionalized β-aminoacrylamides and malononitrile in the presence of potassium carbonate (K₂CO₃) in dimethylsulfoxide (DMSO).

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Poly(4-vinylbenzyl-graft-ethylene glycol methyl ether) (poly(VB-g-mPEG)) amphiphilic graft copolymer was obtained using ‘click’ chemistry of polyethylene glycol methyl ether propargyl (mPEG-propargyl) and terminal azido poly(4-vinylbenzyl chloride) (PVB-N₃). Using 2,2′-azobis(2-methylpropionitrile) and 4-vinylbenzyl chloride, poly(4-vinylbenzyl chloride) (PVBC) was created by free-radical polymerization (FRP). PVB-N₃ was obtained using PVBC and sodium azide. Propargyl chloride and polyethylene glycol methyl ether were reacted to form mPEG-propargyl. The ‘click’ chemical method created poly(VB-g-mPEG) amphiphilic graft copolymer by reacting PVB-N₃ with mPEG-propargyl. ¹H-NMR, DSC, FTIR and GPC characterized the products. The spectroscopic and thermal studies monitored that poly(VB-g-mPEG) was built via combining FRP and ‘click’ chemistry.

Graphical Abstract

The synthesis of poly(4-vinylbenzyl-graft-ethylene glycol methyl ether) amphiphilic graft copolymer was demonstrated in this study by using “click” chemistry and free radical polymerization. The synthesized products were characterized by using ¹H-NMR, DSC, FT-IR, and GPC instruments. Here, we aimed to report on synthesizing the amphiphilic graft copolymer using “click” chemistry and free radical polymerization methods.

This study describes the synthesis and comprehensive characterization of solid solutions in the n (=) 3 and 4 members of the Dion–Jacobson (DJ) family of layered perovskites, (text{A}^prime{text{Ca}}_{2-x})Cd_xNb₃O₁₀ and A′Ca_2-xCd_xNaNb₄O₁₃ (A′ (=) Rb, Cs) (0 ≤ x ≤ 2). In the n (=) 3 series, both Rb and Cs oxides exhibit a transition from centrosymmetric (CS) towards non-centrosymmetric (NCS) polar structures (S.G. Ima2, a_O ~ 29.7 Å, b_O ~ 5.39 Å, c_O ~ 5.43 Å) from x (=) 1 resembling x (=) 2 phases, A′Cd₂Nb₃O₁₀ (A′ (=) Rb, Cs). In the n (=) 4 series, the transitions to acentric polar oxides occur for the Rb analogs (x ≥ 1.75). The polar RbCd₂NaNb₄O₁₃ (n (=) 4) was confirmed through positive second harmonic generation and Le Bail refinements of the PXRD data. Structures of the Cs analogs and the rest of solid solution members including that for Rb adopt a CS tetragonal symmetry (S.G. P4/mmm, a_T ~ 3.9 Å; c_T ~ 18.9 Å), as demonstrated by the Rietveld refinements. Raman spectroscopy corroborates the local distortions of NbO₆ units. Estimation of the optical band gaps and valence and conduction bands energy levels illustrate their utilization for potential photocatalytic applications.

Graphical abstract

The colour wheel reveals the transition from centrosymmetric (CS) to non-centrosymmetric (NCS) structures based on the Cd content in the Dion-Jacobson (n (=) 3, 4) layered perovskite oxides, (text{A}^prime{text{Ca}}_{2-x})CdxNan-3NbnO3n+1 (A′ (=) Rb, Cs; 0 ≤ x ≤ 2.0), forming a significant group of potential functional materials.

Graphene is not an ideal candidate for thermoelectric applications due to its inherent high electrical and thermal conductivity. Graphynes are another class of carbon-based materials that exhibit a unique combination of sp² and sp hybridization in the carbon network. Certain graphynes are promising candidates for thermoelectric applications owing to their semiconducting nature and the presence of acetylenic linkers, i.e. γ-graphyne. In this work, we designed novel forms of biphenylene-based graphynes (BPNYnes) for potential use in thermoelectric applications. Density functional theory (DFT) has been employed to examine the electronic, structural and mechanical properties of various BPNYne nanosheets. The incorporation of the acetylenic π-conjugations altered the metallic nature of the pristine biphenylene monolayer. Boltzmann transport theory-based calculations reveal that the induced band gap in the carbon nanosheets significantly enhances the thermoelectric performance. Notably, 6,8,16-BPNYne nanosheet exhibits promising thermoelectric efficiency, with a figure of merit (ZT) significantly surpassing that of conventional carbon materials such as graphene and graphynes. This study suggests that these novel carbon allotropes could be viable candidates for future thermoelectric devices, offering a combination of high electrical conductivity and optimized Seebeck coefficients.

Graphical abstract

The BPNYne nanosheets resemble graphyne-like carbon networks with excellent dynamic and thermal stability. Notably, 6,8,16-BPNYne nanosheet shows promising thermoelectric efficiency, making it a potential candidate for thermoelectric applications.

The design of enantioselective axially chiral compounds is of great importance in modern synthetic chemistry, biochemistry, and material science due to their potential applications in the pharmaceutical and chemical industries. Traditional approaches to predicting enantioselectivity involve repetitive trial-and-error routines driven by chemical intuition. However, the fast-paced advancements in machine learning offer an alternate way to predict selectivity by leveraging data from laboratory experiments and computational analyses. In our study, we explore various machine learning (ML) techniques to predict the enantioselectivity of reactions using metal-free chiral phosphoric acid (CPA) catalysts in the synthesis of the naphthyl-indole scaffolds. We developed regression-based ML models using molecular descriptors of the reactants, catalysts and key intermediate complexes involved. Despite the limited dataset size, the random forest regression model performed remarkably well, achieving an R² score of 0.88 and RMSE of 0.32 on the test set. This demonstrates the effectiveness of integrating computational and machine learning methodologies in predicting enantioselectivity, marking a significant step forward in the pursuit of efficient, selective, and sustainable asymmetric catalysis.

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A spectrophotometric approach that is straightforward, efficient, highly sensitive, and precise has been devised for quantifying biotin (BTN) in both its pure state and pharmaceutical samples. Therapeutic assessment and patient bioavailability require biotin analysis in biological and pharmacological samples. Some drug detection methods require sophisticated equipment that many quality control laboratories and universities in developing nations lack. The methodology relies on the inhibitory approach of BTN on the Pd(II) promoted ligand substitution (LS) reaction involving 2,2′ bipyridine (BiPy) and hexacyanoferrate(II). The process entails replacing cyanide in [Fe(CN)₆]^4– with BiPy in ammonium dodecyl sulfate (ADS) micellar medium, triggering the development of a complex [Fe(CN)₄ BiPy]^2-. The complex demonstrates a significant level of absorption at a specific wavelength of 440 nm. The established limit of detection for BTN is 0.089 μg mL⁻¹. Experiments on recovery were conducted to confirm the precision and accuracy of BTN quantification. The suggested approach has been effectively utilized for the examination of BTN in pristine samples and various medications, demonstrating remarkable levels of precision and accuracy. The outcomes showed good agreement when compared to the findings of the official analytical method. The excipients typically employed in medicines do not exhibit any interference with the suggested methodology. This methodology effectively determines trace levels of various drugs and biological molecules that can significantly hinder the catalytic efficiency of Pd(II).

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The present study mainly focused on synthesizing novel 2-thioxo-6-(trifluoromethyl)-1,2,3,4-tetrahydropyrimidine-5-carboxamide derivatives using multicomponent reaction. Further, the potential of the synthesized compounds against Plasmodium falciparum dihydrofolate reductase (Pf-DHFR) inhibitors was evaluated by in vitro antimalarial activity, and the results of the study showed moderate to good antimalarial profile of synthesized entities. In-silico research of all the synthesized compounds was conducted using Schrödinger LLC-2020-3 software to explain the binding mode and interactions between molecules and the Pf-DHFR enzyme. To study the drug likeliness of molecules, 3D QSAR and pharmacokinetic studies have been carried out, and the results obtained showed good pharmacokinetics profile of two compounds, namely AMPS-26 and AMPS-28, having good IC₅₀ values concerning standard drugs. Further, the in vitro enzyme inhibition assay results suggested that the synthesized compound interacts nicely with the enzyme and might be used as a potent antimalarial agent.

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The current study presents a synthesis of the novel 2-thioxo-6-(trifluoromethyl)-1,2,3,4-tetrahydropyrimidine-5-carboxamide derivatives using multicomponent reaction. A series of 30 compounds is synthesized. Amongst them, AMPS-28 (IC₅₀ value 0.028 µg/mL) is found to be the most potent against Pf-DHFR enzyme, which is based on its molecular docking studies and IC₅₀ values, comparable to pyrimethamine having IC₅₀ value 0.035 µg/mL.