European Journal of Chemistry
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A square planar copper(II) complex noncovalently conjugated with a p-cresol for bioinspired catecholase activity
Get PDFThis work presents the synthesis of an unprecedented p-cresol-conjugated copper(II) complex as a p-cresol-coupled polydentate ligand, its crystal structure, and catecholase activity. X-ray crystallography reveals that the Cu(II) centre adopts a nearly planar coordination geometry. Crystal data for C14H13Cu0.5O3: Monoclinic, space group P21/c (no. 14), a = 5.9204(2) Å, b = 21.5615(10) Å, c = 9.0715(4) Å, β = 91.266(4)°, V = 1157.72(8) Å3, Z = 4, μ(MoKα) = 0.987 mm-1, Dcalc = 1.498 g/cm3, 12647 reflections measured (6.884° ≤ 2Θ ≤ 63.42°), 3233 unique (Rint = 0.0618, Rsigma = 0.0512) which were used in all calculations. The final R1 was 0.0710 (I > 2σ(I)) and wR2 was 0.2173 (all data). The crystallized p-cresol was localized in complex units through intermolecular O···H interactions and formed a 3D supramolecular framework employing short-ranged O···H and C-H···π interactions in the solid state. The copper(II) complex has been evaluated as a bioinspired catalyst in the oxidative transformation of 3,5-di-tert-butylcatechol (DTBC) to o-benzoquinone in acetonitrile with a high turnover number, 2.26´104 h–1. Electrochemical analysis of the copper(II) complex in the presence of DTBC recommends the generation of a catechol/o-benzosemiquinone redox couple during catalytic oxidation with the generation of hydrogen peroxide as a byproduct
Antioxidant and antimicrobial activities of four medicinal plants from Algeria
Get PDFMedicinal plants are used in folk medicine to cure several human diseases. This work was designed to evaluate the antioxidant and antimicrobial activities of different extracts of Globularia alypum, Dittrichia viscosa, Juniperus oxycedrus, and Retama sphaerocarpa. The total phenolic content (TPC), the total flavonoid content (TFC), and the condensed tannin content (CTC) were determined spectrophotometrically. The antioxidant activity was tested using TAC, DPPH and reducing power assays. The agar diffusion method was used to determine antimicrobial activity against four bacteria (Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa) and one fungus (Candida albicans). J. oxycedrus acetone extract showed the highest extraction yield (35.56±0.45%), TPC (504.96±14.82 mg GAE/g DE) and TFC (43.91±0.87 mg QE/g DE). The same extract exhibited the highest TAC (350.67±6.05 mg GAE/g DE) and was the most effective against the DPPH free radical (IC50 = 0.21±0.01 mg/mL). In contrast, the J. oxycedrus methanol extract showed the highest reducing power (A0.5 = 0.39 ± 0.09 mg/mL). All extracts tested showed antibacterial and anticandidal activities at different concentrations. The best antimicrobial effect was also observed with the acetone extract of J. oxycedrus against P. aeruginosa (26.77±0.06 mm), B. cereus (17.16±0.08 mm), E. coli (15.84±0.04 mm), and C. albicans (21.36±0.11 mm), while the ethanol extract of D. viscosa was the most active against S. aureus (24.54±0.03 mm). The results of this study provide a scientific basis for the traditional use of these local plants and demonstrate their potential as sources of natural antioxidant and antimicrobial bioactive compounds
Synthesis and structural characterization and DFT calculations of the organic salt crystal obtaining 9-aminoacridine and picric acid: 9-Aminoacridinium picrate
Get PDFOrganic salt, 9-aminoacridinium picrate (9-AAcPc), containing equimolar quantities of 9-aminoacridine and picric acid was obtained and a single crystal was grown by the slow evaporation method in the mixture of methanol: tetrahydrofuran solvent (1: 1, v: v). The molecular structure of the prepared compound was confirmed by FT-IR, 1H NMR, and 13C NMR spectroscopic methods, as well as single crystal X-ray diffraction analysis. The X-ray diffraction analysis of the crystal structure of the title compound showed the presence of the triclinic space group P-1 with no. 2, a = 8.2811(7) Å, b = 10.1003(9) Å, c = 13.4484(13) Å, α = 83.521(3)°, β = 83.330(3)°, γ = 66.595(3)°, V = 1022.56(16) Å3, Z = 2, μ(MoKα) = 0.108 mm-1, Dcalc = 1.375 g/cm3, 56338 reflections measured (5.89° ≤ 2Θ ≤ 56.704°), 5097 unique (Rint = 0.0400, Rsigma = 0.0210) which were used in all calculations. The final R1 was 0.0552 (I > 2σ(I)) and wR2 was 0.1757 (all data). The molecular geometry was also optimized using density functional theory. The frontier molecular orbitals were calculated, and we discussed the probability that the proton transfers from the phenolic OH group of picric acid to different nitrogen units. The calculated electronic structure properties of the title molecule, such as the HOMO and LUMO analysis, and different molecular electrostatic potential maps, were obtained by using the density functional theory method, and the calculated structure was compared with the experimental structure. The thermal stability of the crystal was also analyzed using the TGA/DTG technique
Design, synthesis, spectral analysis, and biological evaluation of Schiff bases with a 1,3,4-thiadiazole moiety as an effective inhibitor against bacterial and fungal strains
Get PDFMany distinct natural and pharmaceutical items include the well-known heterocyclic nucleus 1,3,4-thiadiazole. Ten Schiff bases of 1,3,4-thiadiazole derivatives have been synthesized using equimolar amounts of 5-styryl-1,3,4-thiadiazol-2-amine and substituted acetophenones in the catalytic amount of ethanol. The synthesized derivatives of Schiff's bases were characterized by FT-IR, 1H NMR, 13C NMR, and mass spectroscopy. The 1,3,4-thiadiazole Schiff’s bases (RM-1 to RM-10) were tested for their in vitro antimicrobial activity against Pseudomonas aeruginosa, Escherichia coli, Bacillus subtilis, Aspergillus niger, Aspergillus fumigatus, Aspergillus flavus using the disc diffusion method. The 1,3,4-thiadiazole Schiff bases showed strong antibacterial activity against bacterial and fungal species, however, their activity was noticeably less effective than that of the evaluated conventional antibiotics
In an attempt to add ligands to the sixth (axial) position of vanadyl bis-acetylacetonate: A unique tetranuclear vanadyl species
Get PDFWe have explored the interaction of [(acac)2V=O] (acac = acetylacetone) with a series of potential ligands which were chosen because of their expected ability to attach themselves onto its sixth (axial) position. Furthermore, some of the species chosen were expected to have the capability of linking pairs of [(acac)2V=O] molecules, thus creating magnetically coupled substances whose behavior would be interesting to document by magnetic as well as structural methods. Some of the synthetic results were surprising in that unexpected products were obtained which we had not envisioned; specifically, herein we describe a tetranuclear vanadyl cluster (Crystal data for C38H51N4O17ClV4: orthorhombic, space group Pca21 (no. 29), a = 26.4698(3) Å, b = 13.5167(2) Å, c = 12.7659(2) Å, V = 4567.44(11) Å3, Z = 4, μ(CuKα) = 7.842 mm-1, Dcalc = 1.53 g/cm3, 41277 reflections measured (6.538° ≤ 2Θ ≤ 137.892°), 7841 unique (Rint = 0.0428, Rsigma = 0.0421) which were used in all calculations; the final R1 was 0.0675 (I > 2σ(I)) and wR2 was 0.1641 (all data)), which is unusual in several aspects of its composition as well as its stereochemistry
Study on novel biphenyl chalcone scaffolds: A dual spectroscopic approach for efficient sensing of hydrazine with low concentration
Get PDFHydrazine and its derivatives, as harmful substances, seriously risk the health of humans and the environment. On the basis of the admirable luminescent properties and low biological harmfulness of the biphenyl moiety, a biphenyl moiety can be combined with a naphthalene ring via the chalcone scaffold easily traced by a nucleophilic group. Therefore, biphenyl chalcones (BPCs) decorated with various naphthalene systems as fluorescent sensors for hydrazine are synthesised by Claisen-Schmidt condensation. The present work describes the comparative studies of two different protocols for the synthesis of three different BPCs. The structures of all novel BPCs were investigated by FT-IR, NMR, and HRMS spectroscopy. These BPCs show a red shift with a fluorescent peak and an enhancement in intensity with increasing solvent polarity from hexane to methanol. Methanol shows strong fluorescence emission; therefore, methanol is used as the solvent in hydrazine sensing experiments. The BPCs display fluorescent variation from yellow to blue fluorescence after binding with hydrazine. These BPCs sensors are able to identify hydrazine in a fast response rate and 5 min response time. The screening study of hydrazine in various soil samples by prepared BPCs is highly efficient. A study of the pH dependence of these probes shows excellent sensitivity in the pH range of 5 to 10
Overcoming multidrug-resistant bacteria and fungi by green synthesis of AgNPs using Nepeta pogonosperma extract, optimization, characterization and evaluation of antibacterial and antifungal effects
Get PDFThis study explained a green synthesis of silver nanoparticles (AgNPs) using Nepeta pogonosperma extract and evaluated their antibacterial activity. Optimization of the temperature, concentration, pH, and reaction time was established to produce silver nanoparticles. The best condition was 10 mM AgNO3, pH = 14, temperature 85 °C, and reaction time 24 hours. The formation of silver nanoparticles was confirmed by colour-changing, UV-vis, FE-SEM, EDX, XRD, FT-IR, and DLS analysis. The prepared AgNPs had a spherical shape with an average size of 51.21±0.02 nm. In addition, our biofabricated nanoparticles displayed potential antibacterial activity against the tested strains. The MIC value of 1.17 µg/mL was determined against strains of Pseudomonas aeruginosa, Acinetobacter baumannii, and Escherichia coli and 2.34 µg/mL against Staphylococcus aureus, Klebsiella pneumoniae, Proteus mirabilis and Enterococcus faecalis. Furthermore, AgNPs exhibited excellent antifungal effects against Candida albicans strains (0.073 μg/mL). In general, N. pogonosperma played an important role in reducing Ag(+1) to Ag(0) and the production of Ag(0) with suitable surface features in combination with efficient biological activities
Modification and characterization of selected Zambian clays for potential use as photocatalysts
Get PDFNatural materials such as clay are valued for their favorable physical and chemical characteristics on the surface. In this study, the selected Zambian clay materials are immobilized with TiO2 and manganese ions to determine their suitability for use as photocatalysts. SiO2 and Al2O3 oxide composition of Zambian clays was obtained in the range of 35.08-52.63/35.15-52.72 and 13.85-21.73/13.77-21.80, respectively, by inductively coupled plasma (ICP) and X-ray fluorescence (XRF); while Energy dispersive spectroscopy (EDS) of modified clays showed that they have 1.54% incorporation of Ti and 4.98% Mn for Chingola clay to act as UV-Vis absorbers. According to the powder X-ray diffraction analysis of raw clays, the primary phase of all samples is quartz and contains low concentrations of bentonite and kaolinite. The scanning electron microscope (SEM) showed fluffy morphology with agglomeration, while the particle sizes of the clay photocatalysts with the use of transmission electron microscopy (TEM) ranged between 3.0 and 4.8 nm. UV-vis spectroscopy of the samples showed bandgap energies ranging from 2.52-3.08 eV. The surface areas, pore volumes, and pore sizes of the investigated modified and unmodified clays determined by the Brunauer, Teller, Emmett/Barrett Joyner Halenda (BET/BJH) model ranged from 12.06-64.51 m2/g, 0.029-0.068 cm3/g, and 0.642-2.802 nm, respectively. To enhance the mixing of oil and clay, the adsorbents were grafted with silane and confirmed by Fourier transform infrared (FTIR) spectroscopy through CH peaks at ~1450 and ~2860 cm-1. The modified clay materials exhibited favorable properties for use as photocatalysts
