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1.
P. K. Sazonov M. M. Shtern Yu. F. Oprunenko I. P. Beletskaya 《Russian Chemical Bulletin》1998,47(8):1532-1536
The13C and19F NMR spectra ofZ- andE-isomers of β-X-substituted α,β-difluorostyrenes (X=F, Cl, CpFe(CO)2, Re(CO)5, Re2(CO)9Na) were studied. Direct and long-range (across 1–5 bonds) spin-spin coupling constants and the (13C−12C) isotope shifts in the19F NMR spectra were determined. The study of the13C satellites in the19F NMR spectra of substituted difluorostyrenes permitted assignment of the13C NMR signals of the vinylic carbon atoms. Similarly, the signals in19F NMR spectra were assigned based on coupling constants of fluorine withipso-carbon. These assignments were found to be in good agreement with the data available from the literature (X=F, Cl). The developed
approach was applied to the elucidation of the structure ofZ−PhCF=CClFe(CO)2Cp.
Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya. No. 8, pp. 1575–1579, August, 1998. 相似文献
2.
Eliot P. Botosoa Virginie Silvestre Richard J. Robins Jose Manuel Moreno Rojas Claude Guillou Gérald S. Remaud 《Journal of chromatography. A》2009,1216(42):7043-7048
Quantitative isotopic 13C NMR at natural abundance has been used to determine the site-by-site 13C/12C ratios in vanillin and a number of related compounds eluted from silica gel chromatography columns under similar conditions. Head-to-tail isotope fractionation is observed in all compounds at the majority of carbon positions. Furthermore, the site-specific isotope deviations show signatures characteristic of the position and functionality of the substituents present. The observed effects are more complex than would be obtained by simply summing the individual effects. Such detail is hidden when only the global 13C content is measured by mass spectrometry. In particular, carbon positions within the aromatic ring are found to show site-specific isotope fractionation between the solute and the stationary phase. These interactions, defined as non-covalent isotope effects, can be normal or inverse and vary with the substitution pattern present. 相似文献
3.
V. I. Zdanovich V. Yu. Lagunova F. M. Dolgushin A. I. Yanovsky M. G. Ezernitskaya P. V. Petrovskii A. A. Koridze 《Russian Chemical Bulletin》1998,47(9):1789-1796
Ruthenium carbonyl triphenylphosphine complexes Ru2(CO)6−n
(PPh3)
n
{μ-C(CH=CHPh)C(Ph)C(CH=CHPh)C(Ph)} (n=1, 2) were obtained by the reaction of complex Ru2(CO)6{μ-C(CH=CHPh)C(Ph)C(CH=CHPh)C(Ph)} containing the ruthenacyclopentadiene moiety with PPh3 in refluxing toluene. The complexes were characterized by IR and by1H,13C, and31P NMR spectroscopy, and by X-ray analysis. The monophosphine derivative is identical to the complex formed by fragmentation
of the Ru3(CO)8(PPh3){μ-C(CH=CHPh)C(Ph)C(CH=CHPh)C(Ph)} cluster and contains the PPh3 ligand at the ruthenium atom of the ruthenacyclopentadiene moiety.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1836–1843, September, 1998 相似文献
4.
V. Yu. Borovkov S. P. Kolesnikov V. I. Koval’chuk J. L. d’Itri 《Russian Chemical Bulletin》2007,56(5):863-869
Adsorption of 13C18O+12C16O mixtures on the Pt(2.9%)/γ-Al2O3, (Pt(2.6%)+Cu(2.7%))/γ-Al2O3, and (Pt(2.6%)+Cu(5.1%))/γ-Al2O3 catalysts was studied by FTIR spectroscopy. On the metallic Pt surface at coverages close to saturation, CO is adsorbed both
strongly and weakly to form linear species for which the vibrational frequencies of the isolated 13C18O molecules adsorbed on Pt are ∼1940 and ∼1970 cm−1, respectively. The redistribution of intensities of the high-and low-frequency absorption bands in the spectra of adsorbed
13C18O indicates that these linear forms are present on the adjacent metal sites. The weak adsorption is responsible for the fast
isotope exchange between the gaseous CO and CO molecules adsorbed on metal. The Pt-Cu alloys, in which the electronic state
of the surface Pt atoms characteristic of monometallic Pt remains unchanged, are formed on the surface of the reduced Pt-Cu
bimetallic catalysts. The decrease in the vibrational frequencies of the isolated C=O bonds in the isolated Pt-CO complexes
suggests that the CO molecules adsorbed on the Cu atoms affect the electronic properties of Pt.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 831–836, May, 2007. 相似文献
5.
The structure and stability of classical and bridged C2H
3
+
is reinvestigated. The SCF and CEPA-PNO computations performed with flexibles andp basis sets including twod-sets on carbon confirm our previous results. We find the protonated acetylene structure to be more stable than the vinyl
cation by 3.5–4 kcal/mol. The energy barrier for the interconversion of these two structures is at most a few tenths of a
kcal/mol. The equilibrium SCF geometries of Weberet al. [15] are affected insignificantly by further optimization at the CEPA-PNO level.
Several structures for the interaction of C2H
3
+
with HF have been investigated at the SCF level. With our largest basis set which includes a complete set of polarization
functions we find a remarkable levelling of the stabilities of most of the structures. In these cases the stabilization energy
ΔE ranges from −10 to −13 kcal/mol. 相似文献
6.
Characterization of ganoderma spore lipid by stable carbon isotope analysis: implications for authentication 总被引:2,自引:0,他引:2
Liu X Xu SP Wang JH Yuan JP Guo LX Li X Huang XN 《Analytical and bioanalytical chemistry》2007,388(3):723-731
The ratios of stable carbon isotopes (13C/12C) of ganoderma fruiting body, ganoderma spore, ganoderma spore lipid (GSL) and individual fatty acids in GSL were determined
by gas chromatography–stable isotope ratio mass spectrometry and elemental analysis–stable isotope ratio mass spectrometry.
These values fall into a range from −26.9 to −23.3‰, suggesting that the cut log as the Ganoderma-cultivated substrate in Fujian, China, may belong to C3 plants. Eighteen fatty acids were identified and their abundances
measured by gas chromatography–mass spectrometry in the six GSL samples with C16:0, C18:0, C18:1 and C18:2 as major constituents, and C16:1 is evidently enriched compared with the other edible vegetable oils. On the basis of the compositions of fatty acids and
stable carbon isotopes in GSL, we have developed a novel method to detect the adulteration of GSL products with cheaper edible
vegetable oils. An example of ideal blending between GSL and C4 or C3 vegetable oil is further provided to expound the discrimination
procedures and corresponding sensitive indicators. Simultaneously, the carbon isotope fractionation in the biosynthesis of
individual fatty acids was observed, revealing that the formation of C18:0 from C16:0 in ganodema spores had no conspicuous 13C enrichment of +0.4‰ for Ganoderma sinensis spore and +0.1‰ for G. lucidum spore; the desaturation of C18:0 to C18:1 resulted in a distinct 13C depletion of −1.4‰ for G. sinensis spore and −0.9‰ for G. lucidum spore; and the next desaturation from C18:1 to C18:2 displayed no evident 13C fractionation of −0.1‰ for G. sinensis spore and −0.2‰ for G. lucidum spore.
Figure
Ganoderma lucidum has been widely used in traditional Chinese medicines. Ganoderma spore lipid (GSL) extracted from the spores of G. lucidum has been approved as a health food supplement. However, because of rarity, GSL has become a target for adulteration with
cheaper vegetable oils. 相似文献
7.
Methyl-branched fatty acids (MBFAs) are the dominant form of fatty acid found in many bacteria. They are also found at low
levels in a range of foodstuffs, where their presence has been linked to bacterial sources. In this study we evaluated the
potential of compound-specific isotope analysis to obtain insights into the stable carbon isotope ratios (δ13C values in ‰) of individual MBFAs and to compare them to the stable carbon isotope ratios of straight-chain fatty acids in
food. Due to their low abundance in foodstuffs, the MBFAs were enriched prior to gas chromatography coupled to isotope ratio
mass spectrometric (GC–IRMS) analysis. After transesterification, urea complexation was used to suppress the 16:0 and 18:0
methyl esters that were dominant in the samples. Following that, silver-ion high performance liquid chromatography was used
to separate the saturated from the unsaturated fatty acids. The resulting solutions of saturated fatty acids obtained from
suet, goat’s milk, butter, and human milk were studied by GC–IRMS. The δ13C values of fatty acids with 12–17 carbons ranged from −25.4‰ to −37.6‰. In all samples, MBFAs were most depleted in carbon-13,
followed by the odd-chain fatty acids 15:0 and 17:0. 14:0 and 16:0 contained the highest proportions of carbon-13. The results
from this study illustrate that MBFAs have distinctive δ13C values and must originate from other sources and/or from very different substrates. These measurements support the initial
hypothesis that δ13C values can be used to attribute MBFAs to particular sources. 相似文献
8.
Eduardo Marafon Lauro T. Kubota Yoshitaka Gushikem 《Journal of Solid State Electrochemistry》2009,13(3):377-383
SiO2/ZrO2/C carbon ceramic material with composition (in wt%) SiO2 = 50, ZrO2 = 20, and C = 30 was prepared by the sol–gel-processing method. A high-resolution transmission electron microscopy image
showed that ZrO2 and the graphite particles are well dispersed inside the matrix. The electrical conductivity obtained for the pressed disks
of the material was 18 S cm−1, indicating that C particles are also well interconnected inside the solid. An electrode modified with flavin adenine dinucleotide
(FAD) prepared by immersing the solid SiO2/ZrO2/C, molded as a pressed disk, inside a FAD solution (1.0 × 10−3 mol L−1) was used to investigate the electrocatalytic reduction of bromate and iodate. The reduction of both ions occurred at a peak
potential of −0.41 V vs. the saturated calomel reference electrode. The linear response range (lrr) and detection limit (dl)
were: BrO3
−, lrr = 4.98 × 10−5–1.23 × 10−3 mol L−1 and dl = 2.33 μmol L−1; IO3
−, lrr = 4.98 × 10−5 up to 2.42 × 10−3 and dl = 1.46 μmol L−1 for iodate. 相似文献
9.
Prediction of the 13C NMR shifts of sym-pentachlorocorannulene and decachlorocorannulene provided impetus for the development of a correction scheme based on a regression
of experimental and quantum chemical data. A training set of 15 compounds (18 carbon signals) comprising carbons atoms bearing
1–4 chlorine atoms leads to an estimated error per chlorine atom of about 10–12 ppm. Specifically, linear regression of the
data obtained at B3LYP/cc-pVDZ leads to y = −3.77 + 13.11x, with R = 0.982. Ultimately, experiment and theory converge for sym-pentachlorocorannulene and decachlorocorannulene, the former by correction of the theory, the latter by collecting the proper
experimental data.
Contribution to the Mark S. Gordon 65th Birthday Festschrift Issue. 相似文献
10.
A. A. Semioshkin P. V. Petrovskii D. Gabel B. Brellochs V. I. Bregadze 《Russian Chemical Bulletin》1998,47(5):950-955
The sodium salt of [B12H12]2− dianion reacts with carboxylic acid halides to give a mixture of B-acylated product [B12H11COR]2− and an unstable intermediate, the latter undergoing hydrolysis to form [B12H11OH]2−. The ratio of the products formed depends on the nature of the radical R. The reaction mechanism was studied by NMR spectroscopy.
A number of novel [B12H11COR]2− compounds were synthesized; their structures were confirmed by NMR and IR spectral data.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 980–985, May, 1998. 相似文献
11.
[AlO4Al12(OH)24(H2O)12]7+ (Al13) formation in electrolysis process is studied. The results detected by27Al NMR spectroscopy show that high content of Al13 polymer is formed in the partially hydrolyzed aluminum solution prepared by controlled electrolysis process. In the produced
electrolyte of total Al concentration ([AlT]) 2.0 mol · L−1 with a basicity (B = OH/Al molar ratios) of 2.0, the content of Al13 polymer is over 60% of total Al. Dynamic light scattering shows that the size distribution of the final electrolyte solutions
([AlT] = 2.0 mol · L−1) is trimodal with B = 2.0 and bimodal with B = 2.5. The aggregates of Al13 complexes increase the particle size of partially hydrolyzed aluminum solution. 相似文献
12.
Knobbe N Vogl J Pritzkow W Panne U Fry H Lochotzke HM Preiss-Weigert A 《Analytical and bioanalytical chemistry》2006,386(1):104-108
The stable carbon and nitrogen isotopic composition of urine and milk samples from cattle under different feeding regimes
were analysed over a period of six months. The isotope ratios were measured with isotope ratio mass spectrometry (IRMS). The
δ
13C values of milk and urine were dependent on different feeding regimes based on C3 or C4 plants. The δ
13C values are more negative under grass feeding than under maize feeding. The δ
13C values of milk are more negative compared to urine and independent of the feeding regime. Under grass feeding the analysed
milk and urine samples are enriched in 13C relative to the feed, whereas under maize feeding the 13C/12C ratio of urine is in the same range and milk is depleted in 13C relative to the diet. The difference between the 15N/14N ratios for the two feeding regimes is less pronounced than the 13C/12C ratios. The δ
15N values in urine require more time to reach the new equilibrium, whereas the milk samples show no significant differences
between the two feeding regimes. 相似文献
13.
S. N. Tandura N. A. Troitskii S. P. Kolesnikov K. S. Nosov M. P. Egorov 《Russian Chemical Bulletin》1999,48(1):214-217
The complete assignment of the signals in the13C NMR spectra of 2,3,4,5-tetraphenyl-1-R1,R2-1-silacyclopenta-2,4-dienes (R1=R2=H, Me) and of the dianion of lithium salt [(PhC)4Si]2−·2Li+ was carried out by 2D NMR spectroscopy.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 216–218, January, 1999. 相似文献
14.
Isotope ratio mass spectrometry (IRMS) is applied to confirm testosterone (T) abuse by determining the carbon isotope ratios (δ13C value). However, 13C labeled standards can be used to control the δ13C value and produce manipulated T which cannot be detected by the current method. A method was explored to remove the 13C labeled atom at C-3 from the molecule of androsterone (Andro), the metabolite of T in urine, to produce the resultant (A-nor-5α-androstane-2,17-dione, ANAD). The difference in δ13C values between Andro and ANAD (Δδ13CAndro–ANAD, ‰) would change significantly in case manipulated T is abused. Twenty-one volunteers administered T manipulated with different 13C labeled standards. The collected urine samples were analyzed with the established method, and the maximum value of Δδ13CAndro–ANAD post ingestion ranged from 3.0‰ to 8.8‰. Based on the population reference, the cut-off value of Δδ13CAndro–ANAD for positive result was suggested as 1.2‰. The developed method could be used to detect T manipulated with 3-13C labeled standards. 相似文献
15.
Z. A. Kerzina M. I. Rybinskaya F. M. Dolgushin A. I. Yanovsky P. V. Petrovskii E. Kolehmainen 《Russian Chemical Bulletin》1998,47(3):490-495
The reaction of Ru3(CO)12 with tetramethyltrifluoromethylcyclopentadiene at various ratios of the reagents was studied. Refluxing of Ru3(CO)12 with a sixfold excess of tetramethyltrifluoromethylcyclopentadiene in octane in an inert atmosphere gave a complex, which
is, according to X-ray diffraction data, a dimer,trans-[Ru(η5-C5Me4CF3)(CO)2]2. The reaction under the same conditions but starting from Ru3(CO)12 and C5Me4CF3H in 2∶1 molar ratio gave a hexaruthenium cluster [Ru6(μ3-H)(η2-μ4-CO)2(μ-CO)(Co)12(η5-C5Me4CF2)], which was characterized by IR as well as1H,13C, and19F NMR spectroscopy. According to X-ray diffraction data, an Ru4 tetrahedron, in which two edges are bound by additional “briding” Ru atoms, constitutes the frame of this compound. This
complex has one (η5-C5Me4CF3) ligand, as well as one (μ3-H) and two (η2-μ4-CO) groups.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 507–512, March, 1998. 相似文献
16.
Feng-Shou Xiao Ruren Xu Hong Ding Yanan He 《Reaction Kinetics and Catalysis Letters》1997,61(2):383-389
A NaY zeolite entrapped Ru3(CO)12 cluster has been synthesized from RuCl3 ionexchanged NaY, which are well characterized by IR and Raman spectroscopy and CO chemisorption. When the Ru3+/NaY sample is heated from 298 to 393 K for 25 h and kept for 10–20 h at 393 K, the sample color changes from dark to brown-yellow.
Thein situ infrared spectrum exhibits bands at 2130, 2064, 2040, 2017, 1990, 1953 and 1925 cm−1. The bands at 2064, 2040, 2017 and 1990 cm−1 are assigned to Ru3(CO)12/NaY, which are close to crystalline Ru3(CO)12. Furthermore, Raman results provide the bands at 150 and 185 cm−1, which are attributed to Ru-Ru bonds of crystalline Ru3(CO)12). CO chemisorption on [Ru3]/NaY gives a CO/Ru ratio of 3.85, which is similar to the stoichiometry of Ru3(CO)12 (CO/Ru=4.0). 相似文献
17.
The solid state13C NMR spectra of four13CO enriched carbonyl clusters having a tri-iron metallic core have been analyzed to provide structural and dynamic information. In Fe3(CO)12 (1), the high temperature spectra suggest the occurrence of large amplitude motions of the CO groups around their position at the vertexes of the coordination polyhedron in addition to the motion involving the Fe3-triangle previously detected in the VT-13C MAS spectra.13C and31P NMR data of Fe3(CO)11PPh3 (2) indicates the presence of one molecule in the asymmetric unit in apparent disagreement with the previously reported X-ray data. Furthermore, we show that structural information can be obtained from the chemical shift tensor components readily available from the analysis of the spinning sideband manifold. 相似文献
18.
L. G. Detsuheva M. A. Fedotov L. I. Kuznetsova A. A. Vlasov V. A. Likholobov 《Russian Chemical Bulletin》1997,46(5):874-880
Unsaturated heteropolyanions (HPA) [PW11O39]7− stabilize TiIV hydroxo complexes in aqueous solutions (Ti: PW11 [PW11O39]7−⪯12, pH 1–3). Spectral studies (optical,17O and31P NMR, and IR spectra) and studies by the differential dissolution method demonstrated that TiIV hydroxo complexes are stabilized through interactions of polynuclear TiIV hydroxo cations with heteropolyanions [PW11TiO40
5− formed. Depending on the reaction conditions, hydroxo cations Ti
n−1O
x
H
y
m+ either add to oxygen atoms of the W−O−Ti bridges of the heteropolyanions to form the complex [PW11TiO40·Ti
n−1O
x
H
y
]
k−
(at [HPA]=0.01 mol L−1) or interact with TiIV of the heteropolyanions through the terminal o atom to give the polynuclear complexes [PW11O39Ti−O−Ti
n−1O
x
H
y
]q− (at [HPA]=0.2 mol L−1). When the complexes of the first type were treated with H2O2, TiIV ions added peroxo groups.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 914–920, May, 1997. 相似文献
19.
Guyon F Gaillard L Salagoïty MH Médina B 《Analytical and bioanalytical chemistry》2011,401(5):1555-1562
High-performance liquid chromatography linked to isotope ratio mass spectrometry (HPLC-co-IRMS) via a Liquiface? interface has been used to simultaneously determine 13C isotope ratios of glucose (G), fructose (F), glycerol (Gly) and ethanol (Eth) in sweet and semi-sweet wines. The data has
been used the study of wine authenticity. For this purpose, 20 authentic wines from various French production areas and various
vintages have been analyzed after dilution in pure water from 20 to 200 times according to sugar content. If the 13C isotope ratios vary according to the production area and the vintage, it appears that internal ratios of 13C isotope ratios (
R13\textC {R_{{{}^{{13}}{\text{C}}}}} ) of the four compounds studied can be considered as a constant. Thus, ratios of isotope ratios are found to be 1.00 ± 0.04
and 1.02 ± 0.08 for
R13\textC\textG/F {R_{{{}^{{13}}{{\text{C}}_{{{\text{G/F}}}}}}}} and
R13\textC\textGly/Eth {R_{{{}^{{13}}{{\text{C}}_{{{\text{Gly/Eth}}}}}}}} , respectively. Moreover,
R13\textC\textEth/Sugar {R_{{{}^{{13}}{{\text{C}}_{{{\text{Eth/Sugar}}}}}}}} is found to be 1.15 ± 0.10 and 1.16 ± 0.08 for
R13\textC\textGly/Sugar {R_{{{}^{{13}}{{\text{C}}_{{{\text{Gly/Sugar}}}}}}}} . Additions of glucose, fructose and glycerol to a reference wine show a variation of the
R13\textC {R_{{{}^{{13}}{\text{C}}}}} value for a single product addition as low as 2.5 g/L−1. Eighteen commercial wines and 17 concentrated musts have been analyzed. Three wine samples are suspicious as the
R13\textC {R_{{{}^{{13}}{\text{C}}}}} values are out of range indicating a sweetening treatment. Moreover, concentrated must analysis shows that 13C isotope ratio can be also used directly to determine the authenticity of the matrix. 相似文献
20.
Interaction of cobalt cysteinylglycine with histidylserine and histidylphenylalanine was investigated in a 1 : 1 : 1 ratio
at 35°C and 0·10 mol dm−3 ionic strength. Their stabilities and geometries were determined. Their DNA binding and cleavage properties were investigated.
The intrinsic binding constants (K
b
) for DNA bound 1 and 2 (3·03 × 103 M−1 for 1 and 3·87 × 103 M−1 for 2) were determined. Even though the negative charge on the complexes reduced their affinity for DNA, there was an enhancement
of binding through specificity. The degradation of plasmid DNA was achieved by cobalt dipeptide complexes [CoII(CysGly)(HisSer)] (1) and [CoII(CysGly)(HisPhe)] (2). Cleavage experiments revealed that 1 and 2 cleave supercoiled DNA (form I) to nicked circular (form II) through hydrolytic pathway at physiological pH. The DNA hydrolytic cleavage rate constants for complexes 1 and 2 were determined to be 0·62 h−1, for 1 and 0·38 h−1 for 2 respectively. 相似文献