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81.
A novel and efficient synthesis of 1-[(1,2,4-triazole-4-yl)imino]diacetyl monoxime ( L ) is described. The advantages of this method are that it is inexpensive, the starting reactants are readily available, and it has good yield and short reaction times. The hull of the product was suggested by elemental analyses, spectral and single crystal X-ray. Novel Co 2+ , Pd2+, and Fe 3+ chelates derived from L were characterized by Fourier transform infrared spectroscopy, suggesting that L acts as bidentate via the two azomethine groups. Tetrahedral geometry for Fe3+ and Co2+ and square-planar geometry around the Pd2+ chelate were suggested depending on the spectral and magnetic data. The results of density functional theory were applied to illustrate the geometry of L towards the metal ions. Coats–Redfern and Horowitz–Metzger methods were applied to investigate the kinetic and thermodynamic parameters of the chelates. Cyclic voltammetry was carried out to study the stability of the Co2+ and Fe3+ chelates. L and its complexes were tested against three types of cancer cells, antibacterial and antifungal. 相似文献
82.
The conventional condensation and refluxing process was employed to synthesize Ni(II) and Cu(II) complexes of Methylcarbamatethiosemicarbazone ligand. Reactions were carried out at the pH of 7. The molar ratio of the ligand and metal salt was 2:1. The structures of the synthesized metal complexes were suggested by different analytical techniques such as magnetic susceptibility, molar conductance, IR, EPR and UV spectroscopy. Experimental studies confirmed the octahedral geometry for all the complexes. The geometry of the ligand and complexes were also confirmed by theoretical studies. The complexes were investigated for biological action against pathogenic fungi (C. krusei, C. albican) and bacteria (S. aureus, E. coli). The antimicrobial results confirmed superior inhibition potential of the metal complexes as compared with the parent ligand. The enhanced antimicrobial activities might be due to the chelation. Molecular-docking assays confirmed the strong interaction of ligand with target antimicrobial protein DNA gyrase-B. 相似文献
83.
Sreelakshmi Poola Saichaithanya Nagaripati Sreekanth Tellamekala Venkataramaiah Chintha Peddanna Kotha Jayavardhana Rao Yagani 《合成通讯》2020,50(17):2655-2672
Abstract An efficient method for the synthesis of α-aminophosphonate derivatives has been developed with different functional groups under catalyst and solvent free conditions at room temperature in both conventional and ultrasonication methods. Ultrasonication method offers excellent yields within shorter reaction times. All the title compounds 4a–l were tested for their antibacterial, antiviral activity using Gram-positive bacteria (Staphylococcus aureus, and Bacillus subtilis), Gram-negative bacteria (Klebsiella pneumoniae and Escherichia coli) and NDV infected embryonated eggs (in ovo) and NDV infected BHK-21 cell lines (in vitro) respectively. Besides, molecular docking studies were also carried out to the title compounds against Hemagglutinin-neuramidase enzyme to determine the therapeutic binding efficacy of the ligands synthesized. The results indicated that, among the title compounds, compounds such as 4f, 4l, 4k, 4b, 4i and 4h have shown high content of antibacterial and antiviral activity than the rest of the compounds and the level activity was high when compared to the standard, ribavirin. Based on the results, it is concluded that, the reported α-aminophosphonates will open new vistas and stands as a new generation of antiviral and antibacterial drug candidates in future. 相似文献
84.
Dr. Yujia Qing Mira D. Liu Denis Hartmann Dr. Linna Zhou Dr. William J. Ramsay Prof. Hagan Bayley 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(36):15841-15846
We report a single-molecule mechanistic investigation into 2-cyanobenzothiazole (CBT) chemistry within a protein nanoreactor. When simple thiols reacted reversibly with CBT, the thioimidate monoadduct was approximately 80-fold longer-lived than the tetrahedral bisadduct, with important implications for the design of molecular walkers. Irreversible condensation between CBT derivatives and N-terminal cysteine residues has been established as a biocompatible reaction for site-selective biomolecular labeling and imaging. During the reaction between CBT and aminothiols, we resolved two transient intermediates, the thioimidate and the cyclic precursor of the thiazoline product, and determined the rate constants associated with the stepwise condensation, thereby providing critical information for a variety of applications, including the covalent inhibition of protein targets and dynamic combinatorial chemistry. 相似文献
85.
Yang Yu Dr. Martina Delbianco 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(44):9814-9825
The conformation of a molecule strongly affects its function, as demonstrated for peptides and nucleic acids. This correlation is much less established for carbohydrates, the most abundant organic materials in nature. Recent advances in synthetic and analytical techniques have enabled the study of carbohydrates at the molecular level. Recurrent structural features were identified as responsible for particular biological activities or material properties. In this Minireview, recent achievements in the structural characterization of carbohydrates, enabled by systematic studies of chemically defined oligosaccharides, are discussed. These findings can guide the development of more potent glycomimetics. Synthetic carbohydrate materials by design can be envisioned. 相似文献
86.
Dr. A. Nijamudheen Prof. Dr. Ayan Datta 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(7):1442-1487
Transition-metal-catalyzed cross-coupling reactions are central to many organic synthesis methodologies. Traditionally, Pd, Ni, Cu, and Fe catalysts are used to promote these reactions. Recently, many studies have showed that both homogeneous and heterogeneous Au catalysts can be used for activating selective cross-coupling reactions. Here, an overview of the past studies, current trends, and future directions in the field of gold-catalyzed coupling reactions is presented. Design strategies to accomplish selective homocoupling and cross-coupling reactions under both homogeneous and heterogeneous conditions, computational and experimental mechanistic studies, and their applications in diverse fields are critically reviewed. Specific topics covered are: oxidant-assisted and oxidant-free reactions; strain-assisted reactions; dual Au and photoredox catalysis; bimetallic synergistic reactions; mechanisms of reductive elimination processes; enzyme-mimicking Au chemistry; cluster and surface reactions; and plasmonic catalysis. In the relevant sections, theoretical and computational studies of AuI/AuIII chemistry are discussed and the predictions from the calculations are compared with the experimental observations to derive useful design strategies. 相似文献
87.
Mathematics education for students with dis/abilities has a legacy of exclusion; its scholarship has been dominated by ableist perspective: a focus on rote mathematics facts, procedural instruction, and a narrow range of mathematics content. Grounded in critical pedagogy and critical disabilities studies, we argue for a shift in the focus away from the student as the site of defect and intervention to recognize the complex embodiment of dis/ability as a process produced within historical, political, social, and material contexts. The theoretical assumptions and guiding principles for a framework of culturally responsive and relational understanding of dis/ability will be shared together with a case of such an approach in classroom practice. The paper advances efforts to support all learners in robust mathematics learning communities and to situate research from perspectives that acknowledge the situated, interactional nature of ability, identity, and achievement. 相似文献
88.
Ali El-Dissouky Eslam S. Abu-Elsoud Afaf Abdel Razik Mohamed K. Awad Hammed H.A.M. Hassan Amel F. Elhusseiny 《应用有机金属化学》2020,34(11):e5953
A series of nanometer-sized spherical sulfonamide imine ligands HL 1 -HL 5 and their copper and zinc complexes were synthesized and fully characterized based on elemental analyses, spectroscopic (UV/vis, FT-IR, NMR, EPR, SEM) studies, molar conductance and thermal analyses. Furthermore, computational studies of HL 1 -HL 5 were carried out by the DFT/B3LYP method. TD-DFT, HOMO and LUMO energy values, chemical hardness, electronegativity, electrophilic index, softness, and other parameters were calculated. Screening against several pathogenic microorganisms indicated that HL 1 exhibited high activity against the tested Gram-negative bacteria relative to other analogues and the inhibition activity is greater than the standard Gentamicin. Analogously, HL 2 exhibited high potent activity against the tested Gram-positive bacteria. Copper complexes exhibited a higher potent activity than zinc analogues. Noteworthy, inhibition activity of [Cu ( L 3 )(OAc)] complex is higher than that of the standard Ampicillin. [Cu ( L 2 )(OAc)] complex displayed a similar activity of the standard bactericides and fungicides in use. The complexes showed appreciated values of MIC against bacterial strains: B. subtilis (MIC = 0.4 μg / mL), E. coli and S. pneumonia (MIC = 1.95 μg / mL) and P. aeruginosa (MIC = 7.81 μg / mL). in vitro cytotoxic activities study proved that [Cu ( L 3 )(OAc)] complex exhibited appreciable activity versus (HEPG-2); IC50 = 4.8 μg/ml, while [Cu( L 2 )(OAc)] complex showed a high activity against (MCF-7); IC50 = 6.2 μg/ml. These results could be considered as new findings of promising antitumor candidates for experimental chemotherapy. 相似文献
89.
M. Sharma K. Chaudhary M. Kumari P. Yadav K. Sachdev V. Chandra Janu R. Gupta 《Materials Today Chemistry》2020
A green and environment-friendly magnetically separable nanocomposite, glutathione@magnetite was fabricated sonochemically through the functionalization of Fe3O4 by glutathione which was well characterized using Fourier-transform infrared spectroscopy, ultravoilet-visible spectroscopy, scanning electron microscope, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, thermogravimetric analysis, vibrating sample magnetometer, Brunauer-Emmett-Teller, and high-resolution transmission electron microscope. The parameters affecting adsorption including pH, temperature, contact time, initial adsorbate concentration, and adsorbent amount were optimized by batch experiments. The magnetic glutathione@magnetite was applied for the removal of uranium(VI) in water with maximum adsorption capacity found to be 333.33 mg/g in 120 min at a neutral pH at 25 °C showing high efficiency for U(VI) ions. Furthermore, adsorption results obtained from UV-vis spectroscopy were validated by inductively coupled plasma optical emission spectroscopy. The thermodynamic parameters, viz Gibbs free energy (ΔGº), standard enthalpy change (ΔHº), and standard entropy change (ΔSº) of the process were calculated using the Langmuir constants. The pseudo-second-order kinetics model is seen to be applicable for describing the uptake process using a kinetics test. Moreover, desorption studies reveals that glutathione@magnetite can be used repeatedly, and removal efficiency shows only a small decrease after six cycles. Thus, glutathione@magnetite acts as a potential adsorbent for the removal of U(VI) from the water with great adsorption performance. 相似文献
90.