European Journal of Chemistry

The binuclear oxidovanadium(V) complex [{VO(L)}₂(μ-O)(μ-H₂O)]∙2CH₃CN (1), where L^2– is the dianion of the Schiff base 2-salicylaldehyde-2-hydroxybenzoylhydrazone, were prepared and characterized by elemental analysis, FTIR, ¹H, ¹³C and ⁵¹V NMR. Furthermore, the crystal structure of the compound 1 was determined by single crystal X-ray diffractometry revealing a distorted octahedral O₅N-coordination geometry around the V(V) acceptor centers. The vanadium ions are connected by the μ-O^2– and the μ-H₂O asymmetric bridges located in the edge between the two octahedrons which keeps a distance of 3.194 Å between the two vanadium centers. Crystal data for C₃₂H₂₈N₆O₁₀V₂ (M =758.48 g/mol): orthorhombic, space group P2₁2₁2₁ (no. 19), a = 12.9655(8) Å, b = 14.1902(9) Å, c = 18.4379(10) Å, V = 3392.3(4) Å³, Z = 4, T = 293(2) K, μ(MoKα) = 0.616 mm^-1, Dcalc = 1.485 g/cm³, 18803 reflections measured (3.622° ≤ 2Θ ≤ 56.704°), 8263 unique (R_int = 0.0473, R_sigma = 0.1020) which were used in all calculations. The final R₁ was 0.0509 (I > 2σ(I)) and wR₂ was 0.1531 (all data). The (VO)₂(μ-O)(μ-H₂O) core in compound 1 represents a rare case and few examples of similar type have been structurally characterized.

The crystals of bis(4-pyridyl)acetylene are orthorhombic and belong to the space group Fddd. Solid-state investigation using conventional and Hirshfeld analytical techniques revealed valuable data and structural diversities that explain the wide gap between established crystal reports of co-crystals and metal organic frameworks and the pure form of the title compound. Hirshfeld surface analysis in this wise has proved to be a useful tool in unravelling complex intermolecular interactions and simplifying them at the 2D and 3D levels using sub-tools such as fingerprint plots and electrostatic potential surfaces. Both techniques have shown that the H∙∙∙N_pyr interactions in the title compound are shorter than those in its polymorphic counterpart by 0.2 Å. The more stable network provided by hetero-molecular interactions in co-crystals and metal complexes of bis(4-pyridyl)acetylene shed light on their lengthy existence compared to the less favorable homo-molecular interactions in pure molecules of bis(4-pyridyl)acetylene.

Equimolar amounts of imidazoleacetophenone and 2-aminobenzoic acid were combined together and the Schiff base 4(1H-imidazole-yl)acetophenoneanthranilic acid was prepared as a new bidentate complexing agent. The synthesized ligand was reacted with cobalt(II), cadmium(II), and nickel(II) ions yielding air stable complexes. For quantification and characterization purposes, elemental analysis, infrared spectra, electronic spectra, proton nuclear magnetic resonance spectra and mass spectra studies were carried out on the obtained complexes and ligand. Thermogravimetric analysis and magnetic susceptibility measurements were also used for characterization. The ligand IR spectrum showed that the ligand acts as a bidentate coordinates to the metal ions through the nitrogen and oxygen atoms.Measurements of magnetic susceptibility for Ni(II) and Co(II) complexes were found to be 3.4 and 3.8 B.M., respectively, in the range normal for the octahedral geometry. The conductivity measurements revealed that the chelates are non-electrolytes. An in vitro antimicrobial investigation was also carried out for the free ligand and its metal complexes against a number of bacterial and fungal strains, to assess their antimicrobial properties by diffusion technique. Antimicrobial activity of the prepared complexes showed higher activity than the free ligand.

Accurate, rapid and inexpensive determination of gemcitabine, an anticancer drug, is of high interest. This manuscript describes the use of potentiometric sensors as a basis for this work given their known attractive characteristics that meet our needs. Potentiometric sensors were comprised of carbon paste S₁, coated wire S₂ and PVC membrane S₃, of gemcitabine (an anticancer drug) were fabricated, studied and evaluated. The calibration plots for these electrodes showed a Nernstian slope of 58.4±0.3, 59.5±0.3 and 58.3±0.3 mV per decade with the limit of detection: 6.50×10^-5, 7.20×10^-5 and 4.60×10^-5 for sensors S₁, S₂ and S₃, respectively. The electrodes have a short and stable response time of ~5 seconds and good reproducibility in a pH range of 2.5-9.5. The present sensors show distinct selectivity toward the drug ion in comparison to several inorganic ions, sugars, amino acids and some common drug excipients. Gemcitabine was determined successfully in ampoules and urine using these sensors by the calibration curve method.

A virtual docking simulation study was performed on thirty-five newly discovered compounds of N-(2-phenoxy) ethyl imidazo[1,2-a] pyridine-3-carboxamide (IPA), to explore their theoretical binding energy and pose with the active sites of the Mycobacterium tuberculosis target (DNA gyrase). The chemical structures of the compounds were drawn correctly with ChemDraw Ultra software, and then geometrically optimized at DFT level of theory with Spartan 14 software package. Consequently, the docking analysis was carried out using Molegro Virtual Docker (MVD). Five complexes (Complex 5, 24, 25, 33 and 35) with high binding energy were selected to examine their binding pose with the active sites of the protein. The docking results suggested a good MolDock score (≥ -90 kcal/mol) and Protein-Ligand ANT System (PLANTS) score (≥ -60 kcal/mol) which depicted that the compounds can efficiently bind with the active sites of the target. However, compound 5 has the best binding pose with the MolDock score of -140.476 kcal/mol which formed three hydrogen bond interactions with the Gln 538, Ala 531, and Ala 533 amino acid residues. This research gives a firsthand theoretical knowledge to improve the binding efficiency of these compounds with the target.

A very simple, sensitive and highly selective non-extractive new spectrophotometric method has been developed for the determination of molybdenum at nano-trace levels using salicylaldehyde-benzoylhydrazone (Sal-BH). The method is based on the reaction of non-absorbent Sal-BH in a slightly acidic solution (0.0025-0.0075 M H₂S0₄) with molybdenum (VI) to give a light yellowish chelate, which has an absorption maximum at 440 nm. The reaction is instantaneous and absorbance remains stable for over 24 h. The average molar absorption coefficient and Sandell’s sensitivity were found to be 4.32×10⁵ L/mol.cm and 5 ng/cm² of molybdenum, respectively. Linear calibration graphs were obtained for 0.01-60.00 mg/L of molybdenum having detection limit of 1 µg/L and RSD 0.0-2.0 %. The stoichiometric composition of the chelate is 1:1 (Mo:Sal-BH). A large excess of over 60 cations, anions and some common complexing agents (such as chloride, azide, tartrate, EDTA, SCN^- etc.) do not interfere in the determination. The method was successfully used in the determination of molybdenum in several Certified Reference Materials (Alloys, steels, water, hair and bovine liver) as well as in some environmental waters (Potable and polluted), biological samples (Human blood, urine, nails, hair, food and vegetables), soil samples, and solutions containing both molybdenum(VI) and molybdenum(V) as well as complex synthetic mixtures. The results of the proposed method for assessing biological, food and vegetables samples were found to be in excellent agreement with those obtained by ICP-OES and AAS. The method has high precision and accuracy (s = ±0.01 for 0.5 mg/L).

A series of imidazole derivatives (1-3) were synthesized with three component reaction among benzil, ammonium acetate and formaldehyde/aromatic aldehyde at 110 °C without a catalyst and solvent. These synthesized imidazole derivatives have shown intermolecular hydrogen bonding such as N-H···N and O-H···N. The imidazole 1 and 2 exhibited N-H···N intermolecular hydrogen bonding while imidazole 3 exhibited O-H···N intermolecular hydrogen bonding. The hydrogen bonds in imidazoles were studied by X-ray crystallography and Hirshfeld Surface Analysis at d_norm surface which show the visible red spots, indicated for hydrogen bonds. Further, Hirshfeld surface analysis also shows the percentage of all intermolecular interactions.

Emergence of multi-drug resistant strains of Mycobacterium tuberculosis to the available drugs has demanded for the development of more potent anti-tubercular agents with efficient pharmacological activities. Time consumed and expenses in discovering and synthesizing new drug targets with improved biological activity have been a major challenge toward the treatment of multi-drug resistance strain M. tuberculosis. To solve the above problem, Quantitative Structure Activity Relationship (QSAR) is a recent approach developed to discover a novel drug with a better biological against M. Tuberculosis. A validated QSAR model developed in this study to predict the biological activities of some anti-tubercular compounds and to design new hypothetical drugs is influenced with the molecular descriptors; AATS7s, VR1-Dzi, VR1-Dzs, SpMin7-Bhe and RDF110i. The internal validation test for the derived model was found to have correlation coefficient (R²) of 0.8875, adjusted correlation coefficient (R²_adj) value of 0.8234 and leave one out cross validation coefficient (Qcv²) value of 0.8012 while the external validation test was found to have (R²_test) of 0.7961 and Y-randomization Coefficient (cRp²) of 0.6832. Molecular docking shows that ligand 13 of 2,4-disubstituted quinoline derivatives have promising higher binding score of -18.8 kcal/mol compared to the recommended drugs; isoniazid -14.6 kcal/mol. The proposed QSAR model and molecular docking studies will provides valuable approach for the modification of the lead compound, designing and synthesis more potent anti-tubercular agents.

A series of antipyrinyl-pyrazolo[1,5-a]pyrimidines have been synthesized by reactions of aminopyrazole (4) with various formylated active proton compounds in the presence of KHSO₄ (aqueous media), under ultrasound irradiation. The structures of the compounds have been established with the help of spectral and analytical data. N-(1,5-Dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)-7-phenylpyrazolo[1,5-a]pyrimidine-3-carboxamide (6a) was further subjected to X-ray crystallographic studies to avoid any ambiguity of the derived structures. Crystal data for compound 6a, C₅₁H₄₆N₁₂O₅ (M =907.00 g/mol): triclinic, space group P-1 (no. 2), a = 9.9554(3) Å, b = 14.0875(4) Å, c = 17.4572(4) Å, α = 79.676(2)°, β = 85.283(2)°, γ = 72.647(2)°, V = 2297.97(11) Å³, Z = 2, T = 296.15 K, μ(MoKα) = 0.088 mm^-1, Dcalc = 1.311 g/cm³, 29732 reflections measured (4.174° ≤ 2Θ ≤ 57.068°), 10681 unique (R_int = 0.0400, R_sigma = 0.0533) which were used in all calculations. The final R₁ was 0.0566 (I > 2σ(I)) and wR₂ was 0.1663 (all data). The novel compounds were also screened for their biological activities.

A simple, specific, accurate and precise spectrophotometric method was established for simultaneous determination of acetaminophen and caffeine in pure form and in their pharmaceutical formulation commercially known as Panadol Extra^®. Spectrum subtraction has been used in simultaneous determination of both drugs without prior separation. Spectrum subtraction method parameters were validated according to ICH guidelines in which accuracy, precision, repeatability and robustness were found in accepted limits (98-102%). The linearity range was 7.5-45 µg/mL for caffeine and 4-22 µg/mL for acetaminophen with correlation coefficients ≥0.9990 for both drugs. Advantages and disadvantages of spectrum subtraction were discussed and statistical comparison between the proposed method and the reference one was performed.

Drug addiction refers to an out-of-control and compulsive use of substances, which can reach epidemic magnitudes. It is a health concern throughout the world and has major economic impact. Dopamine receptor agonists and antagonists have been cited as molecular targets for the treatment of drug addiction. In this report, the main idea is to analyze the new D3R/D2R ligands that are proposed for the treatment of drug abuse, in terms of their electron donor/acceptor properties. Substances catalogued as agonists represent good electron donors, whereas antagonists represent good electron acceptors. HOMO and LUMO eigenvalues indicate that more energy is necessary to remove an electron from the antagonists, and likewise more energy is gained when antagonists accept an electron. The combination of two molecules (PF-592379 and PNU-177864) produces a new compound (PF-4363467) with properties that are intermediate. Irrespective of the characteristics of the receptor, the classification of ligands is important, in order to further understanding of the reaction mechanism of these compounds. This may help in the design of new molecules for the treatment of drug addiction.