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11.
Hamid?GoudarziafsharEmail author Majid?Rezaeivala Fayezeh?Khosravi Yunes?Abbasityula Somaieh?Yousefi Neslihan??zbek Václav?Eigner Michal?Du?ek 《Journal of the Iranian Chemical Society》2015,12(1):113-119
The ligand 1,2-dimorpholinoethane (DME) was used to prepare Zn(II) and Ni(II) complexes of the general formulation MLX2 (L = DME, X = Cl or NO3). Zinc(II) complex exhibits spectral properties indicative of a distorted tetrahedral geometry, with DME coordinating through two nitrogen atoms and two chlorides completing the tetrahedron. This is in contrast to the six-coordinated, distorted octahedral geometry exhibited by nickel(II) complex of DME when NO3 was used as counter ions. The X-ray diffraction confirms the structures of two complexes and shows that the ligand coordinates through two nitrogen atoms while the two ether linkages are not involved in complexation, which would have been the case if the morpholine rings were in the boat form. The ligand and related complexes have antibacterial activity against the five Gram-positive bacteria: Bacillus subtilis ATCC 6633, Staphylococcus aureus ATCC 6538, Bacillus cereus NRRL-B-3711, Enterococcus faecalis ATCC 29212 and Streptococcus pyogenes and also against the three Gram-negative bacteria: Escherichia coli ATCC 11230, Pseudomonas aeruginosa ATCC 15442 and Klebsiella pneumonia ATCC 70063. The results showed that in some cases the antibacterial activity of the complexes exceeded the one of sulfisoxazole used as a standard. 相似文献
12.
D.?Bajuk-Bogdanovi? S.?Uskokovi?-Markovi?Email author I.?Holclajtner-Antunovi? 《Journal of the Iranian Chemical Society》2015,12(1):137-145
Heteropoly acids (HPA) attract the attention of large variety of scientists, due to HPA’s extraordinary interesting properties and possible application fields. 12-tungstosilicic acid (WSiA), the Keggin type HPA, has some promising characteristic to be used in catalytic processes, but with not well-defined stability. Raman spectroscopy was used for in situ analysis of WSiA hydrolysis in detail in a wide pH range of 1–12. Raman spectroscopy is able to give an almost immediate response/spectrum as a representation of the exact profile/composition of the solution. This method and FTIR spectroscopy, as a complementary technique, enabled recording of the solid and liquid phases of the same sample under different conditions. Our results confirm that the decomposition pathways of WSiA in solution proceed via the formation of the lacunary monovacant anion at pH > 6.4. This anion is a major constituent in pH range up to 9.5. With further increases in pH this species convert to the trivacant lacunary anion. The total decomposition of the Keggin anion to silicate and tungstate occurs at pH > 11.0. The results of the performed study contribute to understand the behavior of WSiA in the water–methanol solution, as the model system of aqueous-organic system. It is concluded that addition of methanol in aqueous solution of WSiA leads to expansion of the pH region where Keggin anion is stable up to 8.1 and above this pH value, precipitation occurs. The obtained data clarify the stability range of WSiA in both water and water–methanol solutions, as well. 相似文献
13.
Javad?SafariEmail author Soheila?Gandomi-Ravandi 《Journal of the Iranian Chemical Society》2015,12(1):147-154
A supported carbon material is shown to be a highly efficient, eco-friendly and recyclable solid acid catalyst for the Biginelli reaction of aldehyde, β-ketoester and urea or thiourea under microwave irradiation in the absence of solvent. This method offers significant advantages such as efficiency, the excellent yield, avoidance of the organic solvents, mild reaction conditions, easy separation and simple operation. In addition, because of employing microwave as heating source and reducing use of organic solvents, this novel method emerges as a green-approach leading to less harmful residues. Furthermore, a mechanism was proposed to rationalize the reaction and the role of NiO–MWCNTs was also investigated in these transformations. 相似文献
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15.
Background
Hydrazones and their metal complexes were heavily studied due to their pharmacological applications such as antimicrobial, anticonvulsant analgesic, anti-inflammatory and anti-cancer agents. This work aims to synthesize and characterize novel complexes of VO2+, Co2+, Ni2+, Cu2+, Zn2+, Zr4+and Pd2+ ions with oxalo bis(2,3-butanedione-hydrazone). Single crystals of the ligand have been grown and analyzed.Results
Oxalo bis(2,3-butanedionehydrazone) [OBH] has a monoclinic crystal with P 1 21/n 1 space group. The VO2+, Co2+, Ni2+, Cu2+, Zn2+, Zr4+ and Pd2+ complexes have the formulas: [VO(OBH–H)2]·H2O, [Co(OBH)2Cl]Cl·½EtOH, [Ni2(OBH)Cl4]·H2O·EtOH, [Cu(OBH)2Cl2]·2H2O, [Zn(OBH–H)2], [Zr(OBH)Cl4]·2H2O, and [Pd2(OBH)(H2O)2Cl4]·2H2O. All complexes are nonelectrolytes except [Co(OBH)2Cl]Cl·½EtOH. OBH ligates as: neutral tetradentate (NNOO) in the Ni2+ and Pd2+ complexes; neutral bidentate (OO) in [Co(OBH)2Cl]Cl·½EtOH, [Zr(OBH)Cl4]·2H2O and [Cu(OBH)2Cl2]·2H2O and monobasic bidentate (OO) in the Zn2+ and VO2+ complexes. The NMR (1H and 13C) spectra support these data. The results proved a tetrahedral for the Zn2+ complex; square-planar for Pd2+; mixed stereochemistry for Ni2+; square-pyramid for Co2+ and VO2+ and octahedral for Cu2+ and Zr4+ complexes. The TGA revealed the outer and inner solvents as well as the residual part. The molecular modeling of [Ni2(OBH)Cl4]·H2O·EtOH and [Co(OBH)2Cl]Cl·½EtOH are drawn and their molecular parameters proved that the presence of two metals stabilized the complex more than the mono metal. The complexes have variable activities against some bacteria and fungi. [Zr(OBH)Cl4]·2H2O has the highest activity. [Co(OBH)2Cl]Cl·½EtOH has more activity against Fusarium.Conclusion
Oxalo bis(2,3-butanedionehydrazone) structure was proved by X-ray crystallography. It coordinates with some transition metal ions as neutral bidentate; mononegative bidentate and neutral tetradentate. The complexes have tetrahedral, square-planar and/or octahedral structures. The VO2+ and Co2+ complexes have square-pyramid structure. [Cu(OBH)2Cl2]·2H2O and [Ni2(OBH)Cl4]·H2O·EtOH decomposed to their oxides while [VO(OBH–H)2]·H2O to vanadium. The energies obtained from molecular modeling calculation for [Ni2(OBH)Cl4]·H2O·EtOH are less than those for [Co(OBH)2Cl]Cl·½EtOH indicating the two metals stabilized the complex more than mono metal. The Co(II) complex is polar molecule while the Ni(II) is non-polar.Graphical abstract
16.
Electrochemical reduction of CO2 has the benefit of turning greenhouse gas emissions into useful resources. We performed a comparative study of the electrochemical reduction of CO2 on stepped Pb(211) and Sn(112) surfaces based on the results of density functional theory slab calculations. We mapped out the potential energy profiles for electrochemical reduction of CO2 to formate and other possible products on both surfaces. Our results show that the first step is the formation of the adsorbed formate(HCOO*) species through an Eley-Rideal mechanism. The formate species can be reduced to HCOO- through a oneelectron reduction in basic solution, which produces formic acid as the predominant product. The respective potentials of forming HCOO* are predicted to be -0.72 and -0.58 V on Pb and Sn. Higher overpotentials make other reaction pathways accessible, leading to different products. On Sn(112), CO and CH4 can be generated at -0.65 V following formate formation. In contrast, the limiting potential to access alternative reaction channels on Pb(211) is -1.33 V, significantly higher than that of Sn. 相似文献
17.
Eliminating the contribution of interfering compounds is a key step in chemical analysis. In complex media, one possible approach is to perform a preliminary separation. However purification is often demanding, long, and costly; it may also considerably alter the properties of interacting components of the mixture (e.g. in a living cell). Hence there is a strong interest for developing separation-free non-invasive analytical protocols. Using photoswitchable probes as labelling and titration contrast agents, we demonstrate that the association of a modulated monochromatic light excitation with a kinetic filtering of the overall observable is much more attractive than constant excitation to read-out the contribution from a target probe under adverse conditions. An extensive theoretical framework enabled us to optimize the out-of-phase concentration first-order response of a photoswitchable probe to modulated illumination by appropriately matching the average light intensity and the radial frequency of the light modulation to the probe dynamics. Thus, we can selectively and quantitatively extract from an overall signal the contribution from a target photoswitchable probe within a mixture of species, photoswitchable or not. This simple titration strategy is more specifically developed in the context of fluorescence imaging, which offers promising perspectives. 相似文献
18.
Yu Shibata Haruki Nagae Shiki Sumiya Rapha?l Rochat Hayato Tsurugi Kazushi Mashima 《Chemical science》2015,6(10):5394-5399
An alkylyttrium complex supported by an N,N′-bis(2,6-diisopropylphenyl)ethylenediamido ligand, (ArNCH2CH2NAr)Y(CH2SiMe3)(THF)2 (1, Ar = 2,6-iPr2C6H3), activated an ortho-phenyl C–H bond of 2-phenylpyridine (2a) to form a (2-pyridylphenyl)yttrium complex (3a) containing a five-membered metallacycle. Subsequently, a unique C(sp2)–C(sp2) coupling of 2-phenylpyridine proceeded through a bimetallic yttrium intermediate, derived from an intramolecular shift of the yttrium center to an ortho-position of the pyridine ring in 3a, to yield a bimetallic yttrium complex (4a) bridged by two-electron reduced 6,6′-diphenyl-2,2′-bipyridyl. Aryl substituents at the ortho-position of the pyridine ring were key in order to destabilize the μ,κ2-(C,N)-pyridyldiyttrium intermediate prior to the C(sp2)–C(sp2) bond formation. 相似文献
19.
20.
Gafurjan?Ibragimov Shravan?LuckrazEmail author 《Journal of Optimization Theory and Applications》2017,175(2):590-596
We give a characterization of robber-win strategies for general pursuit-evasion games with one evader and any finite number of pursuers on a finite graph. We also give an algorithm that solves robber-win games. 相似文献