European Journal of Chemistry
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Synthesis of an eight-membered 2,2,4,6,6,8-hexaphenyl-1,3,5,7,2,6,4,8-tetraoxadisiladiborocane and its reaction with 4,4-azo-pyridine leading to ring contraction to give a dimer and hydrogen bonded macrocyclic siloxane-azo-pyridine
Full text linkWe hereby report the syntheses and characterization of a new dimer of azopyridine connected through the six-membered B-N dative-bonded-adduct Ph8B4Si2O6·L (4) and a hydrogen-bond-induced macrocyclic product 4(Ph2Si(OH)2)·3(C10H8N4) (5). The products were obtained after an eight-membered 2,2,4,6,6,8-hexaphenyl-1,3,5,7,2,6,4,8-tetraoxa disiladiborocane (Ph6B2Si2O4) (3), which is abundant in the literature, was successfully synthesized and characterized by standard analytical and spectroscopic methods such as single-crystal XRD, melting point, nuclear magnetic resonance and Fourier transform infrared spectroscopy. Subsequently, compound 3 and 4,4-azopyridine (L) were reacted in a mixture of diethyl ether and petroleum ether solvents at reflux. This reaction caused a contraction of the eight-membered compound 3 to give two products - a dimer compound 4 (Ph8B4Si2O6·L), and a macrocyclic product 4(Ph2Si(OH)2)·3(C10H8N4) (5). These two products have been characterized by single-crystal XRD, nuclear magnetic resonance, Fourier transform infrared spectroscopy, and melting point. Single crystal X-ray diffraction studies reveal that the dimer compound 4 compound crystalized in the monoclinic crystal system with a centrosymmetric space group of P21/c, a = 11.0879(4) Å, b = 14.3707(4) Å, c = 16.2697(5) Å, β = 98.759(3)°, V = 2562.20(13) Å3, Z = 2. On the other hand, the macrocyclic product 4(Ph2Si(OH)2)·3(C10H8N4) (5) is orange blocky needles that crystallized in the triclinic crystal system with a centrosymmetric space group of P-1, a = 12.2352(3) Å, b = 15.3274(6) Å, c = 20.0271(6) Å, α = 89.879(3)°, β = 89.988(2)° γ = 78.298(3)°, V = 3677.7(2) Å3, Z = 2. Furthermore, compounds 4 and 5 exhibit various noncovalent interactions in crystal packing, such as intermolecular and intramolecular π-π as well as hydrogen bonding. This study demonstrates the potential for making novel materials via the combination of cyclodiboradisiloxane (a Lewis acid) and nitrogen-containing ligand (a Lewis base)
Synthesis and characterization of a novel eight-membered cyclo-1,3,3,5,7,7-hexaphenyl-1,5-dibora-3,7-disiloxane and 4,4ˈ-bipyridine, 1D adduct
Full text linkSimple adducts of cyclo-diboradisiloxanes (Lewis acid) and amines (Lewis base) have been reported in the literature. However, the method for the synthesis of an 8-membered cyclo-diboratetrasiloxane, as well as its adducts, was modified in this report to save cost and achieve new results. In the literature, the synthesis of cyclo-1,3,3,5,7,7-hexaphenyl-1,5-dibora-3,7-disiloxane (Ph6B2Si2O4) (3) has been reported using diphenylsilanediol and phenylboronic acid and a Dean-Stark apparatus for the removal of water. However, in this study, molecular sieves were used for the facile removal of water, and the crude product recrystallized from diethyl ether and petroleum ether (3:1 ratio) to give compound 3. Compound 3 was reacted with 4,4’-bipyridine in a mixture of diethyl ether and petroleum ether solvents at reflux to give a 1D polymer [Ph6B2Si2O4]·L1 (4). Furthermore, compound 4 was characterized with various characterization methods such as single-crystal XRD, nuclear magnetic resonance, and FT-IR spectroscopy. The single crystal X-ray diffraction studies shows that the title compound crystalizes in the triclinic crystal system in the centrosymmetric space group P-1, a = 10.9372(4) Å, b = 18.4221(6) Å, c = 19.4697(6) Å, α = 70.533(3)°, β = 86.476(3)°, γ = 88.517(3)°, V = 3691.6(2) Å3, Z = 2, T = 173.0 K, μ(MoKα) = 0.122 mm-1, Dcalc = 1.204 g/cm3, 21463 reflections measured (5.196° ≤ 2Θ ≤ 56.45°), 14525 unique (Rint = 0.0185, Rsigma = 0.0483) which were used in all calculations, the final R1 was 0.0721 (I > 2σ(I)) and wR2 was 0.2143 (all data) with the 8-membered cyclo-1,3,3,5,7,7-hexaphenyl-1,5-dibora-3,7-disiloxane (Ph6B2Si2O4) (3) configuration
Synthesis, spectral investigation, biological efficacy, and computational evaluation of the hydroxamic acid chelator and its Zn(II) metal complex with potent anticancer activity
Full text linkThe biologically active Zn(II) complex [Zn(HL)2] (HL = 3-OCH3C6H4-(CO)NHO) has been synthesized by the reaction of ZnSO4 with potassium 3-methoxybenzohydroxamate (KHL, 3-OCH3C6H4CONHOK) in a 1:2 molar ratio in MeOH solvent medium simply stirring, avoiding drastic conditions and hazardous chemicals. Physicochemical (elemental analysis, molar conductivity) and spectroscopic studies (FTIR, UV-visible, 1H NMR, and 13C NMR) were conducted to characterize the complex. The coordination involving the oxygen atoms of carbonyl and hydroxamic groups (O,O coordination) and the presence of a distorted tetrahedral geometry around the complex have been inferred on the basis of computational studies. Computational investigations indicate that the complex exhibits greater stability in comparison to that of the ligand, and additional calculations were conducted to assess various chemical reactivity parameters. The biological efficacy of the complex has been evaluated through investigations of its antimicrobial, cytotoxic, and anticancer properties, complemented by DNA binding and docking analyzes. The antimicrobial activity of the ligand and the complex against selected bacteria (S. aureus, S. typhi, E. coli, S. flexneri) and fungi (R. solani, A. alternata, and F. sambucinum) was also evaluated. The complex was found to be more toxic against the bacterial species S. typhi and E. coli and showed efficient inhibitory activity against the fungi F. sambucinum and A. alternata. The results were compared with the standard antibacterial drug tetracycline and the antifungal drug amphotericin B. In vitro cytotoxicity assessments were performed using L20B cell lines, which are malignant mouse cells expressing the human poliovirus receptor (CD155), and Rhabdomyosarcoma RD cancer cell lines derived from muscle tissue. The findings revealed decreased cell viability, which is correlated with the increase in the concentrations of the test compounds, demonstrating potent anticancer activity specifically against rhabdomyosarcoma cancer cell lines. Additionally, molecular docking investigations were performed to explore the molecular interactions between the ligand, the complex, and the crystal structure of the A. alternata allergen (3V0R), further supporting the efficacy of both the ligand and the complex
Ethnobotanical survey and biological activities of plants used for cancer treatment in traditional Senegalese medicine
Full text linkFemale breast cancer is known to be one of the leading causes of death in Senegal. In Senegal, the absence of a national cancer control program, the lack of specialized infrastructure and qualified human resources and the exorbitant cost of care have contributed to the extensive use of traditional medecine, particularly in rural areas. This study aims to inventory the medicinal plants used by these healers and to assess the cytotoxic and antioxidant activities of the most widely used one. Data on healers and their use practices and information on plants were collected through the administration of a structured questionnaire. Based on their citation frequencies during the survey, Antiaris Africana Engler, Hymenocardia Acida Tul. and Halouf Halal (local name) were selected for chemical and biological studies. Their hydroalcoholic extracts were analyzed in terms of antioxidant capacity and cytotoxic effects, again, in the human cancer cell line. The study revealed a total of 65 medicinal plants belonging to 35 different families. The plant parts used by traditional healers are leaves (63.89%), roots (11.11%), bark (15.28%), fruits (2.78%), and others (6.94%). Generally, herbal medicine is prepared as a powder and mixed with water by maceration (55.38%) and administered orally. A. Africana ranked first with a citation frequency of 5.7% and its hydroalcoholic extract had the highest antioxidant activity in TEAC (6533.64±7 μmol ET/g dry plant) and in ORAC (3745.17±4.8 μmol ET/g dry plant) followed by H. Acida in TEAC (3115.6±145 μmol ET/g dry plant) and in ORAC (4105.29±872 μmol ET/g dry plant). The hydroalcoholic extract of A. Africana exhibited the highest cytotoxic activity in MCF-7 (Human mammary) and THP-1 (Human acute monocytic leukemia cell line) but had low activity against HTC-116 (Human carcinoma colorectal) and A-375 (Human skin malignant melanoma). The percentages of proapoptotic cells were, respectively, 68.85±6.22, 58.1±1.90 and 48.58±1.4%. These results provide scientific support for the traditional use of medicinal plants in cancer treatment and constitute a database for biological screening to isolate cytotoxic plant-based molecules
Facile Heck coupling synthesis and characterization of a novel tris(4-(pyridine-4-vinyl)phenyl)methylsilane tridentate core
Full text linkAromatic rigid ligands with carboxylate, phosphate, or pyridyl terminals are highly important today for application in the manufacturing of metal-organic frameworks (MOFs), covalent organic frameworks (COFs), and other supramolecular structures. Aromatic rigid ligands give rigidity to MOFs and COFs materials. In addition, building units are important in that their judicious selection can result in a 2-D or 3-D framework with moderate or high surface area. Most aromatic linkers are based on carbon centres which are associated with a negative impact on the environment. However, in contrast, silicon-based centres are scarce and benign to the environment, even though they can be prepared facilely via metathesis. Here, we report the facile preparation of a new tris (4-(pyridine-4-vinyl)phenyl) methylsilane using the classical Heck coupling reaction. The bridging ligand was synthesized via the standard Heck coupling of 4-vinylpyridine with tris(4-bromophenyl)(methyl)silane
Entropy of the surface catalytic reaction: Expansion of the advanced H2S paradigm to novel catalytic systems
Full text linkThe main provisions of the recently developed concept of the crucial role of catalysts in the process of low-temperature decomposition of H2S to produce hydrogen and elemental sulfur are considered. The concept is based on the non-equilibrium thermodynamics of an irreversible process in an open system. It is shown that irreversible chemical reactions prohibited in the gas phase take place on the catalyst surface under conditions of non-equilibrium thermodynamics at ambient temperature and pressure. This became possible due to the Gibbs free energy accumulated on the catalyst surface as a result of exothermic processes of chemisorption and dissociation of H2S molecules and the dissipation of entropy in the form of bound energy into the environment. The innovative proposed method of H2S utilization will replace the long-outdated Claus method of H2S disposal with the production of water and sulfur (up to 100 million tons per year, more than 1,000 units in the world) with advanced technology to produce hydrogen and diatomic gaseous sulfur. Various types of solid catalysts have been developed to implement advanced technology. The advanced H2S paradigm of catalytic processing allows unexpected chemical reactions to be realized that cannot be carried out by traditional methods under normal conditions. Atomically adsorbed hydrogen and sulfur species formed as a result of H2S dissociation can react with chemically inert molecules of methane, CO2, nitrogen, and argon. It is concluded that at the moment all prerequisites have been created for initiating full-scale scientific, technological, and commercial projects to implement the innovative idea of using the toxic substance H2S to serve humanity
Synthesis and in vitro evaluation of tetrazole containing 1,5-benzothiazepines as new anticancer, antitubercular, antibacterial, and antifungal agents
Full text linkHeterocyclic scaffolds have attracted great attention of organic chemists and medicinal chemists, also because of their wide range of synthetic applicability and broad spectrum of biological profile. Therefore, in the present research work, a series of tetrazole containing 1,5-benzothiazepines have been synthesized for evaluation of their biological activities to determine the potential therapeutic profile of these compounds across various medicinal domains. Of the synthesized compounds, five compounds (6f, 8e, 8f, 8g, and 8h) have been screened for anticancer, antitubercular, antibacterial, and antifungal activities. After evaluation of these biological activities, it was found that these compounds possess very limited anticancer activity, moderate antibacterial and antifungal activity, and very strong antitubercular activity, which indicate their great pharmacological applications as subjects for future investigations of novel therapeutic agents for the treatment of tuberculosis
4-Carboxyanilinium dihydrogen phosphate monohydrate, an organophosphate adducts of 4-amino benzoic acid: Structural, vibrational, thermal, and computational studies
Full text link4-Carboxyanilinium dihydrogen phosphate monohydrate (4-CAH2PO4·H2O), an organophosphate adduct, was synthesized and characterized by single-crystal X-ray diffraction, Fourier transform infrared (FTIR), Differential scanning calorimetry (DSC) and computational analysis performed using CrystalExplorer 21, Gaussian 09W and Multiwfn 3.7 software. The complex 4-CAH2PO4·H2O crystallized in the triclinic space group, P-1, with two molecules each of 4-carboxyanilinium (4-CA) cations, H2PO4– anions, and water, respectively, in an asymmetric unit. Crystal data for C7H12NO7P: triclinic, space group P-1, a = 8.5238(2) Å, b = 8.9068(2) Å, c = 14.4976(4) Å, α = 106.456(2)°, β = 90.195(2)°, γ = 92.811(2)°, V = 1054.13(5) Å3, Z = 4, T = 293 K, μ(Cu Kα) = 2.587 mm-1, Dcalc = 1.595 g/cm3, 18182 reflections measured (6.358° ≤ 2Θ ≤ 146.396°), 4149 unique (Rint = 0.1018, Rsigma = 0.0521) which were used in all calculations. The final R1 was 0.0584 (I > 2σ(I)) and wR2 was 0.1712 (all data). The organic layer containing 4-CA cations and the inorganic layer containing phosphate anions and water molecules in 4-CAH2PO4·H2O crystals are connected through a three-dimensional network of strong charge-assisted N–H···O and C-OH···O hydrogen bonds. The fingerprint plot of 4-CAH2PO4·H2O obtained indicated that the most prominent interaction corresponds to the short O···H contact, followed by the H···H and H···C contacts. The intermolecular interaction topology of 4-CAH2PO4·H2O has been quantitatively analyzed. The 4-CAH2PO4·H2O complex was optimized by density functional theory (DFT) with B3LYP/6-31G basis set and the theoretical IR vibrational spectra determined. The noncovalent interaction (NCI) and quantum theory of the atom in the molecule (QTAIM) analysis were done using Multiwfn 3.7 software. 4-CAH2PO4·H2O complex structure and its computational analysis are also compared with that of 4-carboxyanilinium dihydrogen phosphate (4-CAH2PO4)
Tetrachloro-(acetylacetonato)stannate(IV) and tri-iodocadmate(II) stabilized by a heptacyclic cation: Synthesis, characterization, and crystal structure
Full text linkThe tin (IV) and cadmium (II) complexes were synthesized in mixture, the ligand 4,4'-(ethane-1,2-diylbis(azanylylidene))bis(pent-2-en-2-ol), and the halide metal (SnCl2 or CdI2). Complex synthesis involves partial hydrolysis of the ligand followed by condensation cyclization. The new tin complex obtained crystallizes in the monoclinic space group P21/n with a = 8.5468(5) Å, b = 17.9907(9) Å, c = 12.7227(7) Å, β = 94.220(5) °, V = 1950.98(18) Å3 and Z = 4. The asymmetric unit consists of an anion tetrachloro-(acetylacetonato)stannate(IV) and a heptacyclic cation. The geometry of the complex is octahedral with cis coordination of the two oxygens of the acetylacetone. The cadmium complex crystallizes in the orthorhombic space group Pbca with a = 14.7395(9) Å, b = 8.5914(5) Å, c = 23.2825(13) Å, V = 2948.3(3) Å3, Z = 8. The geometry around cadmium is a deformed tetrahedron. The heptacyclic cation and the anionic complex are interconnected through hydrogen bonding interactions, specifically N–H···Cl or N–H···I, forming a network