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121.
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
122.
Derogis PB Martins FT de Souza TC de C Moreira ME Souza Filho JD Doriguetto AC de Souza KR Veloso MP Dos Santos MH 《Magnetic resonance in chemistry : MRC》2008,46(3):278-282
This article reports the structural elucidation by IR, UV and MS spectroscopic data along with 1H and 13C NMR chemical shift assignments of two benzophenones isolated from the fruit pericarp of Garcinia brasiliensis Mart. (Clusiaceae): garciniaphenone, (1R,5S,7S)-3-benzoyl-4-hydroxy-6,6-dimethyl-5,7-di(3-methyl-2-butenyl)bicyclo[3.3.1]non-3-ene-2,9-dione, a novel triprenylated benzophenone; and 7-epi-clusianone, a tetraprenylated benzophenone that has already been extracted from another species of the same family. Furthermore, the keto-enol tautomeric equilibrium at solution-state was described for these compounds by 1D and 2D NMR spectral methods and one attempt to rationalize the different ratios between the noted tautomers was based on stereochemical features. 相似文献
123.
Viviane A.S. Falcomer Sebastião S. Lemos Guilherme B.C. Martins Gleison A. Casagrande Robert A. Burrow Ernesto S. Lang 《Polyhedron》2007
Complexes of general formula [CuL4][BF4] (L = benzonitrile – PhCN 2 or phenylacetonitrile – BzCN 3) have been prepared and structurally characterized by NMR spectroscopy and X-ray crystallography. Their structure and reactivity have been compared to the well known [Cu(MeCN)4][BF4] (1). The 63Cu line width and the 63Cu chemical shift have been evaluated by varying the temperature and the concentration of the complex 2 in benzonitrile solutions. The phenylacetonitrile solutions of the complex 3 give extremely broad signals which are beyond detection. Accordingly, compound 3 has been studied by 63Cu MAS NMR spectroscopy. The solution NMR data are consistent to the prevalence of dynamic equilibrium between tetra- and low-coordinated species in both complexes. The X-ray structure of 3 revealed that the copper(I) atom sits in a slightly distorted tetrahedral geometry, surrounded by four BzCN ligands. 相似文献
124.
This work aims to verify the impossibility mentioned in the literature of saturating the crystallization kinetics of pre-sheared
metallocene polyethylene melts. Similarly to results reported for other materials, and contrary to other published works,
an acceleration of crystallization kinetics with the increase of shear strain and its saturation at large strain values was
found. Similar strain values, with the same temperature variation, were evaluated with independent experiments using different
devices, which allowed us to identify the steady state as the melt state responsible for the saturation of crystallization
kinetics. Since this is a partially disentangled melt state, with viscosity lower than that of fully entangled (relaxed) melts,
we assign the acceleration of crystallization kinetics by application of shear, and its saturation, mainly to the facilitated
diffusion of chain segments to the lamellae growth front. This conclusion is supported additionally with the experimental
results of other authors. 相似文献
125.
A temperature-insensitive strain sensor based on Four-Wave Mixing (FWM) using two Raman fiber Bragg grating (FBG) lasers with cooperative Rayleigh scattering is proposed. Two FBG were used to form two linear cavities laser sensors based on Raman amplification combined with cooperative Rayleigh scattering. Due to the very low dispersion coefficient of the fiber, it is possible to obtain the FWM using the two lasers. This configuration allows the operation as a temperature-insensitive strain sensor where both sensors have the same sensitivity to temperature but only one of the FBG laser is sensitive to strain. The difference between the wavelengths of the signal sensor and the converted signal presents a strain coefficient sensitivity of 2?pm/??? with insensitivity to temperature. The FWM efficiency is also dependent on the applied strain, but it is temperature independent, presenting a maximum sensibility of 0.01?dB/???. 相似文献
126.
127.
Cadmium determination in biological samples by direct solid sampling flame atomic absorption spectrometry 总被引:1,自引:0,他引:1
rico Marlon de Moraes Flores Jos Neri Gottfried Paniz Ayrton Figueiredo Martins Valderi L. Dressler Edson Irineu Müller Adilson Ben da Costa 《Spectrochimica Acta Part B: Atomic Spectroscopy》2002,57(12):2187-2193
A direct solid sampling flame atomic absorption spectrometric procedure for trace determination of cadmium in biological samples has been developed. Test samples (0.05–2.00 mg) were ground and weighed into small polyethylene vials, which were connected to the device for solid sample introduction into a conventional air/acetylene flame. Test samples were carried as a dry aerosol to a quartz cell, placed between the burner and the optical path, which had a perpendicular entrance and a slit in the upper part. The atomic vapor generated in the flame produced a transient signal that was totally integrated within 1 s. The effect of operating conditions and the extent of grinding on the analytical signal were evaluated. Background signals were always low and a characteristic mass of 0.29 ng Cd was obtained. Calibration was performed using different masses of solid certified reference materials. Results obtained for certified and in-house reference materials were typically within the 95% confidence interval of the certified and/or reference value, and the precision, expressed as relative standard deviation, was between 3.8 and 6.7%. The proposed system is simple and it might be adapted to conventional atomic absorption spectrometers allowing the determination of Cd in more than 80 test samples per hour, excluding weighing. 相似文献
128.
Liliana Costa C.M. da Fonseca Enide Andrade Martins 《Linear algebra and its applications》2008,428(7):1524-1537
In this work we give an interpretation of vertices and edges of the acyclic Birkhoff polytope, Tn=Ωn(T), where T is a tree with n vertices, in terms of graph theory. We generalize a recent result relatively to the diameter of the graph G(Tn). 相似文献
129.
130.
R. D. Maksimov S. Gaidukovs M. Kalnins J. Zicans E. Plume 《Mechanics of Composite Materials》2006,42(2):163-172
A variant of stepwise determination of the elastic characteristics of quasi-isotropic polymer-silicate nanocomposites with
randomly oriented platelike filler particles is considered. First, the elastic constants of transversely isotropic structural
elements with coplanarly placed filler particles are obtained, and then they are averaged over all spatial directions by using
the orientational averaging method. The characteristic features of the hierarchical structure of exfoliated and intercalated
nanocomposites are also considered. The concentration dependences of elastic constants of a nanocomposite based on a styrene-acrylate
copolymer and native montmorillonite clay are modeled, and the results obtained are compared with experimental data.
__________
Translated from Mekhanika Kompozitnykh Materialov, Vol. 42, No. 2, pp. 235–246, March–April, 2006. 相似文献