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81.
Carina R. Martins Lucas C. Ducati Cludio F. Tormena Roberto Rittner 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,72(5):1089-1096
The conformational isomerism of 2-chlorocyclopentanone and 2-bromocyclopentanone has been determined through the solvent dependence of the 1H NMR 3JHH coupling constants, theoretical calculations and infrared data, using the solvation theory for the treatment of NMR data. In 2-chlorocyclopentanone, the energy difference (EΨ-e − EΨ-a), in the isolated molecule at B3LYP level of theory, between the pseudo-equatorial (Ψ-e) and pseudo-axial (Ψ-a) conformers is 0.42 kcal mol−1, which decreases in CCl4 and in acetonitrile solutions, in good agreement with infrared data (νCO), despite the uncertainties of the latter method. The conformational equilibrium for 2-bromocyclopentanone is also between the Ψ-e and Ψ-a conformations, with an energy difference (EΨ-e − EΨ-a), in the isolated molecule at B3LYP level of theory, is 0.85 kcal mol−1 which decreases in CCl4 and in acetonitrile solutions, also in good agreement with infrared data. 相似文献
82.
Pettinari C Marchetti F Lupidi G Quassinti L Bramucci M Petrelli D Vitali LA da Silva MF Martins LM Smoleński P Pombeiro AJ 《Inorganic chemistry》2011,50(21):11173-11183
Five new silver(I) complexes of formulas [Ag(Tpms)] (1), [Ag(Tpms)(PPh(3))] (2), [Ag(Tpms)(PCy(3))] (3), [Ag(PTA)][BF(4)] (4), and [Ag(Tpms)(PTA)] (5) {Tpms = tris(pyrazol-1-yl)methanesulfonate, PPh(3) = triphenylphosphane, PCy(3) = tricyclohexylphosphane, PTA = 1,3,5-triaza-7-phosphaadamantane} have been synthesized and fully characterized by elemental analyses, (1)H, (13)C, and (31)P NMR, electrospray ionization mass spectrometry (ESI-MS), and IR spectroscopic techniques. The single crystal X-ray diffraction study of 3 shows the Tpms ligand acting in the N(3)-facially coordinating mode, while in 2 and 5 a N(2)O-coordination is found, with the SO(3) group bonded to silver and a pendant free pyrazolyl ring. Features of the tilting in the coordinated pyrazolyl rings in these cases suggest that this inequivalence is related with the cone angles of the phosphanes. A detailed study of antimycobacterial and antiproliferative properties of all compounds has been carried out. They were screened for their in vitro antimicrobial activities against the standard strains Enterococcus faecalis (ATCC 29922), Staphylococcus aureus (ATCC 25923), Streptococcus pneumoniae (ATCC 49619), Streptococcus pyogenes (SF37), Streptococcus sanguinis (SK36), Streptococcus mutans (UA159), Escherichia coli (ATCC 25922), and the fungus Candida albicans (ATCC 24443). Complexes 1-5 have been found to display effective antimicrobial activity against the series of bacteria and fungi, and some of them are potential candidates for antiseptic or disinfectant drugs. Interaction of Ag complexes with deoxyribonucleic acid (DNA) has been studied by fluorescence spectroscopic techniques, using ethidium bromide (EB) as a fluorescence probe of DNA. The decrease in the fluorescence of DNA-EB system on addition of Ag complexes shows that the fluorescence quenching of DNA-EB complex occurs and compound 3 is particularly active. Complexes 1-5 exhibit pronounced antiproliferative activity against human malignant melanoma (A375) with an activity often higher than that of AgNO(3), which has been used as a control, following the same order of activity inhibition on DNA, i.e., 3 > 2 > 1 > 5 > AgNO(3)? 4. 相似文献
83.
Complexes of formula [(H2N2O2)TiCl2] and [(H2N2O2)Ti(OiPr)2] (H2N2O2H2 = HOPh’CH2NH(CH2)2NHCH2Ph’OH, where Ph’ = 2,4-(CMe2Ph)C6H2) were synthesized by the reaction of the salan ligand precursor H2N2O2H2 with TiCl4 and Ti(OiPr)4, respectively, in high yields. The dichlorido complex [(H2N2O2)TiCl2] revealed to be an efficient catalyst for the reduction of benzaldehyde in toluene. Full conversion was observed after 24 h at 55 °C in THF. The same catalyst also converted phenylacetaldehyde and hydrocinnamaldehyde into the corresponding alkanes quantitatively. 相似文献
84.
Elenise Bannwart de Moraes Patricia Fazzio Martins César Benedito Batistella Mario Eusebio Torres Alvarez Rubens Maciel Filho Maria Regina Wolf Maciel 《Applied biochemistry and biotechnology》2006,132(1-3):1066-1076
Molecular distillation was studied for the separation of tocopherols from soya sludge, both experimentally and by simulation,
under different operating conditions, with good agreement. Evaporator temperatures varied from 100°C to 160°C and feed flow
rates ranged from 0.1 to 0.8 kg/h. The process pressure was maintained at 10−6 bar, the feed temperature at 50°C, the condenser temperature at 60°C, and the stirring at 350 rpm. For each process condition,
samples of both streams (distillate and residue) were collected and stored at −18°C before tocopherols analyses. Owing to
the differences between molecular weights and vapor pressures of free fatty acids and tocopherols, tocopherols preferentially
remained in the residue at evaporator temperatures of 100°C and 120°C, whereas for higher temperatures (140°C and 160°C) and
lower feed flow rate, tocopherols tended to migrate to the distillate stream. 相似文献
85.
L.L. Tezani R.S. Pessoa R.S. Moraes H.S. Medeiros C.A. Martins H.S. Maciel G. Petraconi Filho M. Massi A. S. da Silva Sobrinho 《等离子体物理论文集》2012,52(9):735-743
In this work is proposed the automation of a gas injection (mass flow) system in order to generate timemultiplex SF6/CH4 radiofrequency plasma applied for silicon (Si) etching process. The control of the gas injection system is important in order to better control the process anisotropy, i.e., the high‐aspect‐ratio of mask pattern transfer to substrate surface. In other words, this control allows the attainment of deep Si etching process. Here, the automation of the gas injection system was realized through the interface between a computer and a data acquisition board. The automation software developed allows controlling the gas flow rate switching it on and off during whole process through the use of a square waveform routine, intermittent flow, beyond the conventional condition of a fixed value for gas flow rate, continuous flow. In order to investigate the time‐multiplex SF6/CH4 plasma etching of Si, the residual gas analysis was performed. The investigations were made keeping the following process parameters: flow of SF6: 10 sccm, flow of CH4: 6 sccm, 100 W rf power, wave period: 20 sec. It were monitored the partial pressure of SF+ 5 (parent neutral specie: SF6), CH+4 (CH4) and SiF+ 3 (SiF4) species as a function of time for different gas flow switching and duty cycle. The results showed that with the generation of plasma occurs a drastic change in behavior of partial pressures of SF+ 5 and CH+4 species. Moreover, it is evidenced that the interactions between the SF6 and CH4 fragments promotes a high production rate of HF molecule and consequently a decrease of atomic fluorine, mainly when plasma is on. Finally, the behavior of partial pressure of SiF+ 3 specie for alternatively intermittent SF6 and CH4 flow operation shows us that both the etching processes and the deposition of a polymer passivation layer are occurring alternatively, a desirable feature for multi‐step etching process (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
86.
Ramon S. Vilela Thiago L. Oliveira Felipe T. Martins Javier A. Ellena Francesc Lloret Miguel Julve Danielle Cangussu 《Comptes Rendus Chimie》2012,15(10):856-865
The preparation, crystal structure and magnetic properties of a new oxalate-containing copper(II) chain of formula {[(CH3)4N]2[Cu(C2O4)2] · H2O}n (1) [(CH3)4N+ = tetramethylammonium cation] are reported. The structure of 1 consists of anionic oxalate-bridged copper(II) chains, tetramethylammoniun cations and crystallization water molecules. Each copper(II) ion in 1 is surrounded by three oxalate ligands, one being bidentate and the other two exhibiting bis-bidenate coordination modes. Although all the tris-chelated copper(II) units from a given chain exhibit the same helicity, adjacent chains have opposite helicities and then an achiral structure results. Variable-temperature magnetic susceptibility measurements of 1 show the occurrence of a weak ferromagnetic interaction through the oxalate bridge [J = +1.14(1) cm−1, the Hamiltonian being defined as H = –J ∑nmSi · Sj]. This value is analyzed and discussed in the light of available magneto-structural data for oxalate-bridged copper(II) complexes with the same out-of-plane exchange pathway. 相似文献
87.
Helio G. Bonacorso Alexandre P. Wentz Rogério V. Lourega Cleber A. Cechinel Tatiana S. Moraes Alex F. C. Flores Nilo Zanatta Marcos A. P. Martins 《Journal of heterocyclic chemistry》2007,44(1):233-236
The regiospecific synthesis of a new series of eight 3‐alkyl(aryl)‐5‐hydroxy‐5‐trichloromethyl‐4,5‐dihydro‐1H‐1‐tosylpyrazoles is reported. The 1‐p‐tosyl‐2‐pyrazolines were obtained from the cyclocondensation reaction of 4‐alkyl(aryl)‐4‐alkoxy‐1,1,1‐trichloroalk‐3‐en‐2‐ones, [where alkyl = H, Me and aryl = ‐C6H5, 4‐CH3C6H4, 4‐OCH3C6H4, 4‐FC6H4, 4‐ClC6H4, 4‐BrC6H4,] with p‐tosylhydrazine in 64 to 92 % yields, employing anhydrous toluene at reflux or diethyl ether at room temperature as the reaction condition. 相似文献
88.
Facile Synthesis and Structural Characterization by NMR,ESI–MS/MS and DFT Calculations of New (E)‐6‐[2‐Ferrocenylalkylidenehydrazino]nicotinic Hydrazides and Their (E)‐Ferrocenyl‐pyrazolyl‐pyridine Heterocyclic System 下载免费PDF全文
Liliane M. F. Porte Gisele R. Paim Thiago G. Schwanz Alexandre R. Meyer Helio G. Bonacorso Marcos A. P. Martins Nilo Zanatta 《Journal of heterocyclic chemistry》2014,51(5):1333-1339
This paper reports a facile and convenient access by a conventional thermal procedure in ethanol as solvent to a new examples of (E)‐6‐[2‐ferrocenylalkylidenehydrazino]nicotinic hydrazides ( 3 ) (53–72%) from the quimioselective reactions of 6‐hydrazinonicotinc hydrazide ( 1 ) with acylferrocenes ( 2 ), where acyl = formyl and acetyl. Subsequently, cyclocondensation reactions of ferrocenylalkylidene hydrazones ( 3 ) with 4‐R1‐4‐alkoxy‐1,1,1‐trifluoroalk‐3‐en‐2‐ones ( 4 ), where R1 = Me, Ph, 2‐Furyl, to obtain new six heterocyclic derivatives as (E)‐pyrazolyl‐pyridinohydrazones ( 5 ) (58–63%), are also presented. The structures of these new heterocyclic compounds 5 containing an organometallic unit were characterized and studied by NMR, ESI–MS/MS techniques. DFT calculations were also employed to assign the E configuration for compounds 3 and 5 . 相似文献
89.
Nida Sheibat‐Othman Ana‐Maria Cenacchi‐Pereira Amilton Martins Dos Santos Elodie Bourgeat‐Lami 《Journal of polymer science. Part A, Polymer chemistry》2011,49(22):4771-4784
We report the kinetics and mechanism of soap‐free emulsion polymerization of styrene using laponite platelets as stabilizers. The polymerization was initiated by potassium persulfate and the latex particles were stabilized by laponite platelets dispersed in water. Laponite adsorption on the polymer particles was enhanced by the addition of poly(ethylene glycol) monomethylether methacrylate (PEGMA). Particle nucleation can be described using the classical homogeneous nucleation mechanism followed by coagulation of unstable precursors. Oligomeric radicals formed in the water phase become insoluble and precipitate on the laponite surface leading to primary precursor particles composed of a few polymer chains and one or several clay platelets. Mature latex particles are then generated by coagulation and growth of the previously formed precursor particles. Both the nucleation and initial aggregation rates increased in the presence of PEGMA. Calorimetric monitoring of the polymerization allowed estimating the heat produced by the reaction and the monomer conversion. Hence, using the monomer material balance, the number of radicals in the polymer particles could be estimated precisely. The average number of radicals per particle, $ \bar n $ , was found to be high in the range 3–6. This result was attributed to strong attractive interactions between the growing radicals and the clay surface. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011. 相似文献
90.
Maria Helena Godinho Assis Farinha Martins Mohamed Naceur Belgacem Luís Gil Nereida Cordeiro 《Macromolecular Symposia》2001,169(1):223-228
This paper deals with the use of cork powder, a by‐product from cork industry, as a filler to reinforce hydroxypropyl cellulose (HPC) matrix. Several films were prepared using HPC, as a matrix, filled with different amounts of cork powder (average diameter < 50 μm) (0.0; 0.5; 1.0 and 10.0% w/w) and in the presence or not of 1,4‐diisocyanatobutane (BDI) (7.0% w/w). Before the elaboration of these films, the surface properties of cork powder as well as that of suberin (main component of cork) were determined by Inverse Gas Chromatography (IGC). The tensile properties of the solid films obtained were studied and, as expected, for the films with BDI but without cork powder, the Young's modulus and the tensile strength increased, while the elongation decreased. However with the filled films it seemed that the Young's modulus decreased and the elongation increased. The Scanning Electron Microscopy showed that the fractured plane of samples with cross‐linking agent and cork powder displayed some nucleation points (0.3 μm) which indicates a strongly bonded interface and which could be considered as a responsible for the high mechanical properties observed. 相似文献