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311.
Two novel membrane sensors sensitive and reasonably selective for Cu2+ ions are described. These are based on the use of newly synthesized cyclic tetrapeptide derivatives as neutral ionophores and sodium tetraphenylborate (NaTPB) as an anionic excluder in plasticized PVC membranes. The sensors exhibit fast and stable near-Nernstian response over the concentration range 1.0 × 10−6 mol l−1 to 1.0 × 10−2 mol l−1 Cu2+ with a cationic slope of 30.2-25.9 mV per decade at pH 4.5-7 with a lower detection limit of 0.05-0.13 μg ml−1. Effects of plasticizers, lipophilic salts and various foreign common ions are tested. The sensors display long life-span, long term stability, high reproducibility, and short response time. Selectivity of both sensors is significantly high for Cu2+ over Fe3+, Al3+, Zn2+, Cd2+, Hg2+, Ni2+, Co2+, Mn2+, alkaline earth and alkali metal ions. The sensors are used for direct measurement of copper content in different rocks and industrial wastewater samples from electroplating factories. The results agree fairly well with data obtained using atomic absorption spectrometry. 相似文献
312.
Summary
Oxidation of the diaqua(nitrilotriacetato)cobaltate(II) complex, [CoIInta(H2O)2]-, by NBS has been studied in aqueous medium.
The kinetics of the reaction in the presence of an iron(II) catalyst obey the rate law:
Catalysis by iron(II) is believed to be due to the oxidation of iron(II) to iron(III), which acts as the oxidizing agent.
The thermodynamic activation parameters were calculated and we propose that electron transfer proceeds through an inner-sphere
mechanism.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
313.
Unexpected 4,4′‐dipyrazolomethylidene ( 7 ), 4‐amino‐3a‐bromo‐3‐methyl‐1‐phenylpyrazolo[3,4‐b]pyridin‐6‐thione ( 9 ), 4,4′‐dipyrazolyl ( 18 ), ethyl 4‐(3‐methyl‐1‐phenylpyrazole‐4‐yl)fuoro[2,3‐c]pyrazole‐4‐carboxylate ( 25 ), as well as the expected fuoro[2,3‐c]pyrazole derivatives ( 15 ), ( 20 ) and ( 28 ) were isolated from a one‐pot reaction of 4‐bromo‐3‐methyl‐1‐phenylpyrazole ( 1 ) with some readily available reagents. 相似文献
314.
Adel A.-H. Abdel-Rahman Ahmed E.-S. Abdel-Megied Mohamed A. M. Hawata Eman R. Kasem Mohamed T. Shabaan 《Monatshefte für Chemie / Chemical Monthly》2007,138(9):889-897
Summary. Chalcones were synthesized by a base catalyzed Claisen-Schmidt condensation reaction. Bromination of chalcones afforded the dibromo derivatives. Monobromo derivatives could be obtained
by treating the corresponding dibromochalcones with dry benzene in the presence of triethylamine. Pyrazole derivatives were
obtained by refluxing of dibromochalcones with phenylhydrazine or 2,4-dinitrophenylhydrazine in dry pyridine. Chalcones were
treated with hydrazine hydrate or phenyl hydrazine in ethanol to afford Δ
2-pyrazolines and N-phenyl-Δ
2-pyrazolines. Condensation of chalcones with hydroxylamine hydrochloride or thiourea in ethanolic sodium hydroxide solution
gave 4,5-dihydroisoxazoles and 5,6-dihydropyrimidine-2-(1H)-thiones. The prepared compounds were tested for antimicrobial activity against four different bacterial species displaying
different degrees of antibacterial activities or inhibitory actions. 相似文献
315.
316.
AbstractThe high functionality compound namely 2-cyano-3-(1,3-diphenyl-1H-pyrazol-4-yl)acryloyl chloride (1) was utilized as a building block synthon via reactions with some nitrogen and sulfur nucleophilic reagents. The present work was planned to study the effect of 2-cyano group on the reactivity and stability of C2–C3 double bond toward different strong-to-weak nucleophiles, in addition to its facility of nucleophilic addition at C2–C3 double bond to construct new heterocyclic derivatives. The proclivity toward some mono-, 1,2-, 1,3-, 1,4-, and 1,5-binucleophiles was investigated. The reaction with 2-cyanoacetohydrazide was mainly dependent on the reaction conditions. Some new heterocycles integrated with pyrazole scaffold were successfully synthesized, such as benzoxazinone, indoline, isoindoline, pyrazolone, chromene, and pyrimidopyrimidine derivatives. Some of the newly synthesized compounds were screened for their antioxidant activity using ABTS method, and the results revealed that some compounds exhibited promising inhibitory antioxidant activity. 相似文献
317.
Walaa S. El‐serwy Hanaa S. Mohamed Weam S. El‐serwy Neama A. Mohamed Emad M. M. Kassem Eman S. Nossier Al Shimaa G. Shalaby 《Journal of heterocyclic chemistry》2019,56(7):2027-2035
A new series of thiopyrimidine‐5‐carbonitrile derivatives were synthesized and the chemical identity of them was established on the basis of spectral methods. The antimicrobial properties of all derivatives were investigated against Gram‐positive and Gram‐negative bacteria as well as fungal strains. The results of the antimicrobial screening showed that compounds 4 , 11 , and 12 have a higher and broad spectrum efficacy against all the tested organisms in comparison with the reference drugs. Interestingly, the most active compounds 4 and 12 showed good binding assay results with Escherichia coli DNA gyrase comparable to that of the reference, methotrexate. Furthermore, a molecular docking study of these compounds was carried out to investigate their binding pattern with the target, DNA gyrase. 相似文献
318.
Sally Elmogy Mohamed A. Ismail Rabeay Y. A. Hassan Ahmed Noureldeen Hadeer Darwish Eman Fayad Fahmy Elsaid Ashraf Elsayed 《Molecules (Basel, Switzerland)》2021,26(1)
Resistance of bacteria to multiple antibiotics is a significant health problem; hence, to continually respond to this challenge, different antibacterial agents must be constantly discovered. In this work, fluoroaryl-2,2′-bichalcophene derivatives were chemically synthesized and their biological activities were evaluated against Staphylococcus aureus (S. aureus). The impact of the investigated bichalcophene derivatives was studied on the ultrastructural level via scanning electron microscopy (SEM), molecular level via sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) method and on the biofilm inhibition via the electrochemical biosensors. Arylbichalcophenes’ antibacterial activity against S. aureus was affected by the presence and location of fluorine atoms. The fluorobithiophene derivative MA-1156 displayed the best minimum inhibitory concentration (MIC) value of 16 µM among the tested fluoroarylbichalcophenes. Over a period of seven days, S. aureus did not develop any resistance against the tested fluoroarylbichalcophenes at higher concentrations. The impact of fluoroarylbichalcophenes was strong on S. aureus protein pattern showing high degrees of polymorphism. SEM micrographs of S. aureus cells treated with fluoroarylbichalcophenes displayed smaller cell-sizes, fewer numbers, arranged in a linear form and some of them were damaged when compared to the untreated cells. The bioelectrochemical measurements demonstrated the strong sensitivity of S. aureus cells to the tested fluoroarylbichalcophenes and an antibiofilm agent. Eventually, these fluoroarylbichalcophene compounds especially the MA-1156 could be recommended as effective antibacterial agents. 相似文献
319.
Awad ED El-Abadelah MM Matar S Zihlif MA Naffa RG Al-Momani EQ Mubarak MS 《Molecules (Basel, Switzerland)》2011,17(1):227-239
A new series of 6-substituted-4-methyl-3-(4-arylpiperazin-1-yl)cinnolines 8-10 were synthesized as potential antifungal agents via intramolecular cyclization of the respective 1-(2-arylhydrazono)-1-(4-arylpiperazin-1-yl)propan-2-ones 5-7, mediated by polyphosphoric acid (PPA). The amidrazones themselves were synthesized via direct interaction of the appropriate hydrazonoyl chlorides 4a-d with the corresponding N-substituted piperazine in the presence of triethylamine. The structures of the new prepared compounds were confirmed by elemental analyses, (1)H-NMR, (13)C-NMR, and ESI-HRMS spectral data. The antitumor, antibacterial, and antifungal activity of the newly synthesized compounds was evaluated. 相似文献
320.
Ibrahim E. El Aassy Mohamed M. El Galy Afaf A. Nada Mohamed G. El Feky Thanaa M. Abd El Maksoud Shadia M. Talaat Eman M. Ibrahim 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(1):173-184
The contents of natural radionuclides in various types of sedimentary rocks in Um Bogma Formation and base of El Hashash Formation
were determined by gamma-ray spectrometry. Three types of lower Carboniferous sedimentary rocks were investigated; sandstone
(El Hashash Formation), dolostone and argillaceous sediments (Um Bogma Formation). The alteration processes are dolomitization,
dedolomitization, karstification and lateritization. The specific radioactivity of 238U, 226Ra, 232Th and 40K determined in different samples, indicate that 238U and its decay products contribute primarily to the high natural radioactivity of rocks. The maximum concentration of 238U reached up to 2129.36 ppm in argillaceous sediments. The average concentrations of determined radionuclides (238U, 226Ra, 232Th and 40K) are 8.34 ppm, 7.88 ppm, 4.68 ppm and 0.3%, respectively in sandstone. In dolostones the average concentrations are 418.69 ppm,
808.75 ppm, 3.14 ppm and 0.29%, respectively. For argillaceous sediments are 276.88 ppm, 419.49 ppm, 11.47 ppm and 0.93%,
respectively. The 238U/226Ra ratio in sandstone ranges between 0.89 and 1.25, while in dolostones and argillaceous sediments are 0.27–2.63 and 0.27–1.83,
respectively. These variations in the concentrations of radioelements and their ratios are due to the action of the alteration
processes affected these different sedimentary rocks in different times. Environmentally, the Raeq in dolostones and argillaceous sediments exceeds the permitted limits, while in the sandstone samples; it is within the permissible
levels. 相似文献