Journal of Chemical Sciences最新文献

Optically active dithiophosphoric and dithiophosphonic acids bearing glucofuranose and galactopyranose diacetonide substituents reacted with racemic atropine to give atropinium dithiophosphates or dithiophosphonates as the mixture of diastereomers. Dithiophosphoric and dithiophosphonic acids and their atropinium salts possess antimicrobial activity.

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SYNOPSIS: Optically active dithiophosphoric and dithiophosphonic acids bearing α-D-glucofuranose and α-D-galactopyranose diacetonide substituents reacted with racemic atropine to give atropinium dithiophosphates or dithiophosphonates as the mixture of diastereomers. Dithiophosphoric and dithiophosphonic acids and their atropinium salts possess antimicrobial activity.

N-acyl serinols, the amphiphilic molecules produced by gastrointestinal bacteria regulate metabolic hormone production and glucose homeostasis in the host species, and also exhibit anti-cancer activity. In this study, molecular structure, supramolecular organization and intermolecular interactions of two N-acylserinols (NASOHs), viz., N-nonanoylserinol (N9SOH) and N-pentadecanoylserinol (N15SOH), are determined by single-crystal X-ray diffraction. The molecular structure and packing are compared and discussed with the structurally related molecules, N-acylethanolamine (NAE) and N-acyl tris (NAT) as NASOHs and NATs are derived by substituting one/two α-hydrogen(s) (with respect to amide N-H) of NAE with hydroxymethyl group(s). Structures of N9SOH and N15SOH were solved in the triclinic system in the P-1 space group and both molecules are organized in a tilted head-to-head (and tail-to-tail) manner, resembling a bilayer membrane. The acyl chains in N9SOH and N15SOH are tilted by 20.43° and 18.12°, respectively, with respect to the bilayer normal. Several N—H⋯O, O—H⋯O, and C—H⋯O hydrogen bonds between the hydroxyl and amide moieties of the head groups of NASOH molecules belonging to adjacent and opposite layers stabilize the overall supramolecular organization. These results suggest that the α-hydroxymethyl groups exhibit considerable influence on the crystal structure, molecular packing, and phase structure of these amphiphiles.

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Removing one of the CH₂OH moieties of N-acylserinol gives N-acylethanolamine, whereas introducing one more CH₂OH moiety on the α-carbon gives N-acyltris. While both N-acylethanolamine and N-acylserinol adopt tilted bilayer structure, the larger head group of N-acyltris induces it to adopt an interdigitated bilayer structure.

The present study deals with a highly efficient and regioselective synthesis of 7-aryl-5-methyl- and 5-aryl-7-trifluoromethyl-2-amino-3-(4′-arylazo)-pyrazolo[1,5-a]pyrimidines via multicomponent reaction of hydrazine hydrate, 2-(arylhydrazono)malononitrile and β-diketones in presence of p-toluenesulphonic acid under solvent-free condition. The structure of the isolated products was established on the basis of NMR (¹H, ¹³C, and ¹⁹F) and IR spectral data. The scope of the reaction was studied using various β-diketones viz., aliphatic, aromatic, heteroaromatic, and trifluoromethyl-β-diketones. The protocol has several advantages, such as mild conditions, atom economy, practical simplicity, shorter reaction times, and avoidance of multi-step procedures. Seventeen diversely substituted pyrazolo[1,5-a]pyrimidines were screened against two breast cancer cell lines, named MCF-7 and BT474, and two leukemia cell lines, named NALM-6 and SB-ALL, using the MTT cytotoxicity assay. Preliminary results reveal that compound 2-amino-5-(4-bromophenyl)-3-(4-methoxyphenylazo)-7-(trifluoromethyl)pyrazolo[1,5-a]pyrimidine was identified as the most effective compound against all the four cancer cell lines with 65-49% cell survival.

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An efficient regioselective synthesis of 7-aryl-5-methyl- and 5-aryl-7-trifluoromethyl-2-amino-3-(4′-arylazo)-pyrazolo[1,5-a]pyrimidines is developed using solvent-free sequential multicomponent reaction of hydrazine hydrate, 2-(arylhydrazono)malononitrile with unsymmetrical β-diketones.

In this report, CuBi₂O₄ and CuBi₂O₄/MnO₂ are synthesized using coprecipitation and hydrothermal methods, respectively. CuBi₂O₄/MnO₂ has been extensively used for the electrochemical detection of hydroxylamine. CuBi₂O₄ and CuBi₂O₄/MnO₂ are well characterized by XRD, XPS, and FESEM to reveal the structural and morphological features of the material. Electrochemical measurements like CV, chronoamperometry, and impedance are studied to reveal the electrochemical behavior of CuBi₂O₄/MnO₂ towards hydroxylamine. Stability, reproducibility, and interference studies are performed to reveal the suitability of CuBi₂O₄/MnO₂ as an electrode material for the electrochemical detection of hydroxylamine.

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CuBi2O4 and CuBi2O4/MnO2 are synthesized using coprecipitation and hydrothermal methods, respectively, and tested for the electrochemical detection of hydroxylamine. CuBi2O4/MnO2 exhibited a high sensitivity of 488 μA mM⁻¹ cm⁻² with a limit of detection 0.86 μM, revealing its ability to display good electrochemical activity towards hydroxylamine.

The development of straightforward synthetic and characterization methods for selenopeptides is essential to discovering hierarchical structured functional materials. Here, the synthesis of a series of homo-selenopeptides 1-4, having the benzyl (Bzl) group-protected selenocysteine [(Bzl)SeCH₂CH(NH₂)COOH] monomer units in the sequence, is reported. The homo-selenopeptides 1-4 are characterized by 1D (¹H, ¹³C, and ⁷⁷Se) and 2D (¹H-¹H COSY, ¹H-¹H NOESY, and ¹H-¹H TOCSY) NMR spectroscopy, and ESI-MS spectrometry. The triselenopeptide 1 shows a propensity for self-assembly into β-sheet amyloid-like fibril structure in acetonitrile (ACN) solution at room temperature. This has systematically been analyzed and established through the spectroscopic techniques; FT-IR, CD, and ThT-based fluorescence spectroscopy for secondary bonding analyses and microscopic techniques; SEM and TEM for the amyloid-like fibril structure in ACN solution. The amide I band vibrational stretching frequencies observed in the range 1600-1700 cm⁻¹ confirm that all peptides in the homologous series have a strong propensity to form amyloid-like fibril structures.

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Synthesis of a series of homo-selenopeptides 1-4 through the solid-phase peptide synthesis (SPPS), using Fmoc protected Sec(Bzl)-OH as a source of amino acid, has been described. Spectroscopic and morphological imaging studies revealed that the homo-selenopeptides have a high propensity to get self-organized into amyloid-like fibrillar structures.

The molybdate-incorporated hydrotalcite-type α-Ni(OH)₂ catalysts were prepared by the post-synthesis method. The synthesized catalyst was thoroughly studied using several physicochemical characterization methods. The catalytic activity of the material was studied on biomass model compounds such as anisole hydrotreating and the oxidation of iso-eugenol. The catalyst shows a significant conversion for the anisole hydrotreating in vapour phase conditions, yielding a steady-state conversion of 30% even after 10 h of time-on-stream (TOS). The primary product was benzene, with other products, viz., methyl anisole, methylcyclohexane, and toluene, as minor components. The catalyst also has the potential for iso-eugenol oxidation and shows 76.1% conversion with 75.5% selectivity for vanillin at 100 °C, 5 h.

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Molybdate-incorporated hydrotalcite-type α-Ni(OH)₂ catalysts have the potential for oxidation of iso-eugenol to vanillin in the presence of an oxidant in a liquid phase and hydro-deoxygenation in the vapour phase under a hydrogen atmosphere.

A green method for synthesizing 1,4-dihydropyridines (1a-j) by a one-pot reaction of various aldehydes, ethyl acetoacetate, and ammonium carbonate, catalyzed by a seashell and kaolin powders, mixed and calcined at 500 and 800 °C, under solvent-free conditions, has been developed. The catalyst was characterized by physicochemical techniques, namely, X-ray diffraction (XRD), electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The mixture composed of 20% seashell and 80% Kaolin (Q3-500), calcined at 500 °C, gave the best results (78 to 96% yields). Q3-500 separation from the reacting medium was carried out by filtration and reused several times with a slight decrease in yields. Compared with other conventional methods, the present method is inexpensive and offers advantages, namely: the catalyst is eco-friendly, recyclable, and gives high yields with shorter reaction time.

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A seashell/Kaolin calcined system (20/80) at 500°C was elaborated to catalyze the Hantzsch reaction under solvent-free conditions. Using Q3-500 six times gave dihydropyridines with excellent yields with a slight loss of activity. The improvement of the catalytic properties of the kaolin surface is due to the increase of cationic content.

Structure vis-à-vis the stability of mono- and poly-atomic buckminsterfullerene (C(_{60})) complexes are capable of providing intrigue information about these systems. To obtain an insight of these complexes, geometrical parameters of fullerene encapsulated noble gas elements (He, Ne and Ar) and poly-atomic molecules (H(_2), H(_2)O, NH(_3) and CH(_4)) are computed at the restricted Hartree-Fock (RHF) as well as density functional (DFT) at the Becke, 3-parameter, Lee-Yang-Parr (B3LYP) level of theories. Ellipticity values estimated from mean maximal and mean minimal diameters of these endohedrals are found to be (sim)0.2 which indicate that these complexes are of spheroidal shape. It is further observed that the fullerene ring is resilient to deformation and the structural parameters of these systems depend more on the method than the embedded system. Binding energies of these complexes are computed at the RHF, DFT, second order Möller-Plesset perturbation (MP2), spin-component scaled (SCS) MP2 and coupled-cluster with single and double excitation (CCSD) level of theories to assess electron correlation effects on the stability of these endohedrals. Resulted energies from the RHF procedure are found to be positive (energetically unstable), whereas those yielded by MP2 and SCS-MP2 procedures predict these endohedrals to be stable. CCSD calculations also exhibit similar trend except for H(_2)O complex. Binding energies obtained using RHF, MP2, SCS-MP2 and CCSD procedures with correlation consistent polarized basis indicate a strong correlation between the basis set and the stability of these endohedral complexes.