Spectroscopic and Quantum Mechanical Studies of Substituted Anilines and their Charge-Transfer Complexes with Iodine in Different Solvents

Summary. Equilibrium constants and molar extinction coefficients for 1:1 charge-transfer complexes between 2-hydroxyaniline (HA), 5-chloro-2-hydroxyaniline (CHA), and 4-bromo-2,6-dimethylaniline (BMA) as donors and iodine, as a typical σ-acceptor were determined spectrophotometrically in chloroform, dichloromethane, and carbontetrachloride solutions. Spectral characteristics and formation constants are discussed in terms of donor molecular structure and solvent polarity. The stoichiometry of the complexes was established to be 1:1. For this purpose, optical data were subjected to the form of the Rose-Drago equation for 1:1 equilibria. Electronic absorption spectra of the studied anilines were measured in different solvents. Spectral data were reported and band maxima were assigned to the appropriate molecular orbital transitions (π–π^* and n–π^* electronic transition). Solvent effects on the electronic transitions were discussed. Optimized geometry of the studied anilines was obtained at B3LYP/6-31 + G(d). The effect of the electronic factors of the substituents on the geometrical parameters of the ring has been explored. Geometrical values of the ring deviate from the regular hexagonal ring. Intramolecular H-bonds in HA and CHA have been computed at B3LYP/6-31 + G(d) and MP2/6-31 + G(d) levels. The H-bonding distance was calculated to be 2.105 ? in HA and 2.127 ? in CHA. Abstracted from her M.Sc. thesis     

Synthesis of Potential Antiviral Agents for SARS-CoV-2 Using Molecular Hybridization Approach

We synthesized a set of small molecules using a molecular hybridization approach with good yields. The antiviral properties of the synthesized conjugates against the SAR-CoV-2 virus were investigated and their cytotoxicity was also determined. Among all the synthesized conjugates, compound 9f showed potential against SARS-CoV-2 and low cytotoxicity. The conjugates’ selectivity indexes (SIs) were determined to correlate the antiviral properties and cytotoxicity. The observed biological data were further validated using computational studies.     

Optimized Green Extraction of Polyphenols from Cassia javanica L. Petals for Their Application in Sunflower Oil: Anticancer and Antioxidant Properties

The total phenolic content (TPC) from Cassia javanica L. petals were extracted using ethanolic solvent extraction at concentrations ranging from 0 to 90% and an SCF-CO₂ co-solvent at various pressures. Ultrasound-assisted extraction parameters were optimized using response surface methodology (RSM). Antioxidant and anticancer properties of total phenols were assessed. An SCF-CO₂ co-solvent extract was nano-encapsulated and applied to sunflower oil without the addition of an antioxidant. The results indicated that the best treatment for retaining TPC and total flavonoids content (TFC) was SCF-CO₂ co-solvent followed by the ultrasound and ethanolic extraction procedures. Additionally, the best antioxidant activity by β-carotene/linoleic acid and DPPH free radical-scavenging test systems was observed by SCF-CO₂ co-solvent then ultrasound and ethanolic extraction methods. SCF-CO₂ co-solvent recorded the highest inhibition % for PC3 (76.20%) and MCF7 (98.70%) and the lowest IC₅₀ value for PC3 (145 µ/mL) and MCF7 (96 µ/mL). It was discovered that fortifying sunflower oil with SCF-CO₂ co-solvent nanoparticles had a beneficial effect on free fatty acids and peroxide levels. The SCF-CO₂ method was finally found to be superior and could be used in large-scale processing.     

First synthesis of selenadiazolo[3,4‐i] Benzazepine derivatives

5‐Methyl‐4‐nitro‐2,1,3‐benzoselenadiazole ( 1 ) was converted into (E)‐5‐(2‐dimethylamino)vinylbenzo‐[c](1,2,5)selenadiazole‐4‐amine ( 4 ) by initial treatment with dimethylformamide dimethyl acetal (DMFDMA) ( 2 ) followed by selective reduction using ammonium bromide in methanol. Compound 4 afforded the selenadiazolo[3,4‐i][1]benzazepine derivatives ( 7, 10, 13, 15 ) upon treatment with malononitrile ( 5 ), ethyl cyanoacetate ( 8 ) and cyanoacetamide ( 11 ) respectively.     

Synthesis and preliminary investigations of the siRNA delivery potential of novel, single-chain rigid cationic carotenoid lipids

The success of nucleic acid delivery requires the development of safe and efficient delivery vectors that overcome cellular barriers for effective transport. Herein we describe the synthesis of a series of novel, single-chain rigid cationic carotenoid lipids and a study of their preliminary in vitro siRNA delivery effectiveness and cellular toxicity. The efficiency of siRNA delivery by the single-chain lipid series was compared with that of known cationic lipid vectors, 3β-[N-(N',N'-dimethylaminoethane)carbamoyl]-cholesterol (DC-Chol) and 1,2-dimyristoyl-sn-glyceryl-3-phosphoethanolamine (EPC) as positive controls. All cationic lipids (controls and single-chain lipids) were co-formulated into liposomes with the neutral co-lipid, 1,2-dioleolyl-sn-glycerol-3-phosphoethanolamine (DOPE). Cationic lipid-siRNA complexes of varying (+/-) molar charge ratios were formulated for delivery into HR5-CL11 cells. Of the five single-chain carotenoid lipids investigated, lipids 1, 2, 3 and 5 displayed significant knockdown efficiency with HR5-CL11 cells. In addition, lipid 1 exhibited the lowest levels of cytotoxicity with cell viability greater than 80% at all (+/-) molar charge ratios studied. This novel, single-chain rigid carotenoid-based cationic lipid represents a new class of transfection vector with excellent cell tolerance, accompanied with encouraging siRNA delivery efficiency.     

New One Pot‐synthesis of Functionally Substituted Pyridines from Enaminoketones

Several new pyridine derivatives were prepared via reaction of enaminoketones 1a , 1b , 1c , 1d with active hydrogen reagents. Reaction of the enaminoketones 1a , 1b , 1c with 4‐acetyl‐1,5‐dimethyl‐2‐phenyl‐1H‐pyrazol‐3(2H)‐one 2a yielded the pyridines 3a , 3b , 3c . Condensation of the enaminonitrile 1d with compounds 2b , 2c , 2d and compound 8 gave the pyridine derivatives 6a , 6b , 6c and 10 respectively. Also, (3‐(dimethylamino)acryloyl)‐2H‐chromen‐2‐one 1a reacted with active methylenes in diethyl 3‐oxopentanedioate 12 and 4‐methyl‐6‐oxo‐2‐thioxo‐1,2,5,6‐tetrahydropyridine‐3‐carbonitrile 15 to afford the pyridine derivatives 14 and 16 respectively.     

An eco-friendly multi-analyte high-performance thin layer chromatographic densitometric determination of amoxicillin,metronidazole, and famotidine in their ternary mixtures and simulated gastric juice: A promising protocol for eradicating Helicobacter pylori

Gastrointestinal tract disorders constitute a heavy burden to healthcare providers. To eradicate Helicobacter pylori infection, different triple therapy protocols have been proposed. Among which are combinations of proton pump inhibitors (e.g., omeprazole), histamine-2 receptor antagonists (e.g., famotidine), along with antibiotics (e.g., amoxicillin). In this work, a sensitive and accurate high-performance thin-layer chromatographic method was developed for the simultaneous determination of amoxicillin, metronidazole, and famotidine in bulk powder and laboratory-prepared combined-tablet mixtures. Complete separation of the cited compounds was achieved using pre-coated silica gel plates with a mixture of methanol:chloroform:toluene:water:glacial acetic acid (5:2:1.5:0.5:0.1 v/v/v/v/v) as the mobile phase. The method was fully validated as per the international conference of harmonization guidelines. Good linearity, a correlation coefficient of 0.9991, was obtained in the concentration ranges 0.1–1.6 μg/band (amoxicillin), 0.1–0.9 μg/band (metronidazole), and 0.1–0.9 μg/band (famotidine). Since the method allowed the determination of the three compounds in combined tablets with a high degree of selectivity, accuracy, precision, with cost-effectiveness, it could be used for regular quality control. Moreover, the applicability of the proposed method was extended to the determination of the ternary mixture in simulated gastric juice. Method greenness was assessed using different green metrics.     

A Convenient Regiospecific Synthesis of New Conjugated Tetrazole Derivatives via the Reaction of Dienones with the Tetrachlorosilane-Sodium Azide Reagent and their NMR Structural Assignment

Summary. Several new 1-aryl-, aralkyl-, and heteroaryl-5-(4-phenylbuta-1,3-dienyl)tetrazole derivatives and annulated tetrazole derivatives were efficiently and regiospecifically prepared in nearly quantitative yield via a facile one step reaction of dienones with a combination of tetrachlorosilane and sodium azide in acetonitrile under mild conditions. A complete structure assignment of three representative examples of the tetrazoles was achieved by advanced 2D NMR measurements including COSY, TOCSY, HSQC, HMBC, NOESY, and ROESY experiments.Received March 17, 2003; accepted March 18, 2003 Published online July 28, 2003     

Synthesis and Properties of Mononuclear and Homobinuclear Chelates of Mn(II), Co(II), Ni(II), and Cu(II) with Phthalein Purple

Mono- and homobinuclear complexes of Mn(II), Co(II), Ni(II), and Cu(II) with phthalein purple are prepared and characterized by elemental analysis, thermal studies (TGA and DTA), spectral methods (IR, UV/Vis, and ESR), magnetic moment determination, and electrochemical reduction (DC polarography at DME and CV at HMDE). Thermal degradation of the complexes was studied by TGA and DTA where some thermodynamic parameters were determined. The mode of bonding and geometry of the complexes were determined from the spectral studies. Magnetic moment values showed some antiferromagnetism in the homobinuclear complexes. The reduction of the metal ions proceeds to the metallic state along an irreversible process.