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1.
T. V. Tyumkina I. F. Nuriev L. M. Khalilov V. R. Akhmetova U. M. Dzhemilev 《Chemistry of Natural Compounds》2009,45(1):61-65
The structure of a new compound was determined using PMR and 13C NMR spectroscopy (HHCOSY, HSBC, HMBC, ROESY) as 2-[3′-methoxy,4-O-β-D-galactopyranos-1-yl)benzyl]-3-(3″,4″-dimethoxybenzyl)-4hydroxybutyric acid, which was isolated for the first time from
seeds of Scotch thistle Onopordum acanthium L.
*For No. XII, see [1].
Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 53–55, January–February, 2009. 相似文献
2.
Yu. K. Grishin I. P. Gloriozov S. M. Gerdov V. A. Roznyatovsky L. L. Frolova A. V. Kuchin Yu. A. Ustynyuk 《Russian Chemical Bulletin》2008,57(8):1689-1696
The selectivity of deuterium distribution between the nonequivalent positions in 3-carene (1), 4-α-acetyl-2-carene (2), and 4-(1-hydroxyethyl)-2-carene (3) has been measured by 2H-{1H} NMR spectroscopy at the natural abundance of deuterium. These “H/D-isotope portraits” were shown to be typical of terpenes
and terpenoids produced in plants via the biosynthetic DXP pathway. The mechanism of acylation of 1 was studied by the density functional theory method (PBE functional, TZ2p basis set). The six-membered ring in compound 1 is planar. However, the endo attack of electrophiles on this ring is more favorable both kinetically and thermodynamically. It was shown both experimentally
and theoretically that the elimination of a hydrogen atom in the second reaction step proceeds stereoselectively at the C(2)
atom from the anti position with respect to the three-membered ring and occurs with pronounced nucleophilic assistance from the carbonyl group.
For Part 2, see Ref. 1.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1657–1664, August, 2008. 相似文献
3.
Lenoble V Garnier C Masion A Ziarelli F Garnier JM 《Analytical and bioanalytical chemistry》2008,390(2):749-757
This work allowed the characterization of the Cd-binding sites of two compounds taken as models for exudates, the main components
of soil organic matter (SOM). The studied compounds were exopolysaccharides (EPS), specifically exudates of roots (polygalacturonic
acid) and of soil bacteria (Phytagel). Potentiometric acid–base titrations were performed and fitting of the obtained results
indicated the presence of two main classes of acidic sites, defined by their pK
a values, for both EPS but of a different nature when comparing the two compounds. The two studied exopolysaccharides presented
different acidic/basic site ratios: 0.15 for Phytagel and 0.76 for polygalacturonic acid. Spectroscopic techniques (13C/113Cd NMR, FTIR) distinguished different Cd surroundings for each of the studied EPS, which is in agreement with the titration
results. Furthermore, these analyses indicated the presence of –COOH and –OH groups in various proportions for each exopolysaccharide,
which should be linked to their reactivity towards cadmium. Cadmium titrations (voltammetric measurements) also differentiated
different binding sites for each compound and allowed the determination of the strength of the Cd-binding site of the EPS.
Fitting of the results of such voltammetric measurements was performed using PROSECE (Programme d’Optimisation et de Speciation Chimique dans l’Environnement), a software coupling chemical speciation calculation and binding parameter optimization. The fitting, taking into account
the Cd2+/H+ competition towards exopolysaccharides, confirmed the acid-base titrations and spectroscopic analyses by revealing two classes
of binding sites: (i) one defined as a strong complexant regarding its Cd2+–EPS association (logK = 9–10.4) and with basic functionality regarding H+–EPS association (pK
a = 11.3–11.7), and (ii) one defined as a weak complexant (logK = 7.1–8.2) and with acidic functionality (pK
a = 3.7–4.0). Therefore the combination of spectroscopic analyses, voltammetry, and fitting allowed the precise characterization
of the binding sites of the studied exopolysaccharides, mimicking the main SOM components. Furthermore, the binding parameters
obtained by fitting can be used in biogeochemical models to better define the role of key SOM compounds like exudates of roots
and of soil bacteria on trace metal transport or assimilation. 相似文献
4.
The photoluminescence properties of xZnO–(100−x)SiO2 (x = 0, 5, 10, 20) containing 1% Eu2O3 prepared by a sol–gel method were systematically investigated. The results indicated that the relative proportion of f–f transitions to charge transfer (CT) absorption decreased with the increase of ZnO concentration. The intensity of 5D0–7FJ transitions of Eu3+ ions was enhanced with the increase of ZnO content due to local structure changes and decreased quantities of Eu3+ ions clusters. The results of fluorescence line narrow (FLN) spectra indicated that Eu3+ ions occupied one site in SiO2 glass and two sites in ZnO–SiO2 glasses. The second-order crystal field parameters were calculated. B20 and B22 for site 1 increased with excitation energy, while ones hardly changed for site 2. 相似文献
5.
V. V. Dotsenko S. G. Krivokolysko V. P. Litvinov 《Chemistry of Heterocyclic Compounds》2007,43(11):1455-1459
5,11-Disubstituted derivatives of 1′-isopropyl-8-thioxospiro[3,5,7,11-tetrazatricyclo[7.3.1.02,7]tridec-2-ene-13,4′-piperidine]-1,9-dicar bonitrile was obtained by the interaction of 10-amino-9-aza-3-azonia-7,11-dicyano-3-isopropylspiro[5,5]undeca-7,10-diene-8-thiolate
with 2 equiv. of a primary amine and excess of formaldehyde. An anomalous reaction product was obtained with o-toluidine — 7,9-dicyano-1′-isopropyl-3-(2-methylphenyl)-1,2,3,4-tetrahydrospiro[pyrido[1,2-a][1,3,5]triazine-8,4′-piper idinium]-6-thiolate.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, 1709–1713, November, 2007. 相似文献
6.
A. N. Simonov O. P. Pestunova L. G. Matvienko V. N. Parmon 《Russian Chemical Bulletin》2005,54(8):1967-1972
Isomerization of D-glucose to fructose and mannose in aqueous solutions of Ca(OH)2 with the initial pH 11.4 in a temperature interval of 20–90 °C was studied by 13C NMR spectroscopy in the presence and absence of dissolved oxygen. In the presence of oxygen, the apparent equilibrium isomerization
constant is much lower than that in the absence of oxygen. This is related to the oxidation of monosaccharides to formic and
aldonic acids, a decrease in the pH of solutions, and cessation of isomerization at pH < 9.
__________
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1909–1913, August, 2005. 相似文献
7.
A. A. Kamyshova A. Z. Kreindlin P. V. Petrovskii A. S. Peregudov Yu. A. Borisov A. A. Koridze 《Russian Chemical Bulletin》2005,54(12):2805-2812
The reaction of [Cp*2RuBr]+Br− with bromine in CH2Cl2 (CD2Cl2) in an inert atmosphere at room temperature produces the complexes [Cp*Ru(Br)C5Me4CH2Br]+Br3
− (syn conformer), [Cp*Ru(Br)C5Me3(CH2Br)2]+ (syn and anti conformers), and [Ru(Br)(C5Me4CH2Br)2]+ (syn conformer). All complexes were characterized by 1H and 13C NMR spectroscopy; the former complex, by elemental analysis. These complexes were also prepared by the reaction of [Cp*RuC5Me4CH2]+BF4
− with bromine in CH2Cl2.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2712–2718, December, 2005. 相似文献
8.
E. V. Starodubtseva O. V. Turova M. G. Vinogradov L. S. Gorshkova V. A. Ferapontov 《Russian Chemical Bulletin》2005,54(10):2374-2378
The rate of hydrogenation of γ-ketoesters MeCOCH2CH2COOR (R = Et, Pri, But) in the presence of the chiral RuII—BINAP catalyst (BINAP is 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl) greatly increases upon the addition of 5–10 equivalents
of HCl with respect to ruthenium. In the hydrogenation of ethyl levulinate, the optically active γ-hydroxy ester initially
formed would cyclize by ∼95% to give γ-valerolactone with optical purity of 98–99% ee. When the Ru(COD)(MA)2—BINAP—HCl catalytic system is used (COD is 1,5-cyclooctadiene, MA is 2-methylallyl), complete conversion of the ketoester
(R = Et) in EtOH is attained in 5 h at 60 °C under an H2 pressure of 60–70 atm.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2301–2304, October, 2005. 相似文献
9.
Revital Sasson Dan Vaknin Avihai Bross Efraim Lavie 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(3):753-756
A practical and reliable HPLC method was used for the determination of 2-[4-N-(2-hydroxyethyl)-1-piperazinyl]-N′-ethanesulfonic acid (HEPES) content in the 68Ga-labeled [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]-1-Nal3-octreotide (DOTANOC). Linearity of this method
was observed in a concentration range of 0.01–10 mg mL−1 and the quantitative limit (signal to noise = 11) was determined as 10 μg mL−1. The HEPES concentration in the final products of 68Ga-DOTANOC was typically lower than the detection limit. Pure water and HEPES buffer as reaction medium were investigated
using various activities of gallium-68. It was demonstrated that the presence of HEPES buffer consistently furnished very
high radiochemical purity of 68Ga-DOTANOC, which remained stable for several hours post-labeling. Evidence is provided that in addition to its role as a
buffer, HEPES also functions as a radioprotectant agent. 相似文献
10.
Reactions of 2-(4,5-dihydro-3-furyl)-1,3-diphenyl-1,3-diaza-2λ3-phospholidine (1) with nitrile imines are multistep processes involving cleavage of one P-N bond of the diazaphospholidine ring to form substituted
5-(2-chloroethyl)-4-(N,N′-diphenylethylenediamino)-1,4-dihydro-1,2,4λ5-diazaphosphorines 4 as final products. Analogs of phospholidine 1, namely, 4,5-dihydro-3-furylphosphonous dipiperidide and dimorpholide, react with C,N-diphenylnitrile imine with retention of both P-N bonds to give 5-(2-hydroxyethyl)-1,2,4-diazaphosphorinium chlorides.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1590–1593, July, 2005. 相似文献
11.
Victor V. Dotsenko Sergey G. Krivokolysko Alexander N. Chernega Victor P. Litvinov 《Monatshefte für Chemie / Chemical Monthly》2007,138(1):35-42
Summary. 3,5,7,11-Tetraazatricyclo[7.3.1.02,7]tridec-2-ene derivatives were prepared in one-pot manner from N-methylmorpholinium 6-amino-3,5-dicyano-4-spiro(1′-cycloalkane)-1,4-dihydropyridine-2-thiolates, primary amines, and formaldehyde
in 70–88% yields. The structure of 5,11-dibenzyl-13-spiro(1′-cyclopentane)-8-thioxo-3,5,7,11-tetraazatricyclo[7.3.1.02,7]tridec-2-ene-1,9-dicarbonitrile was determined by X-ray diffraction analysis. 相似文献
12.
Prithwiraj Byabartta 《Transition Metal Chemistry》2005,30(7):804-813
Ag+ assisted aquation of blue cis-trans-cis-RuCl2(RaaiR′)2 (4–6) leads to the synthesis of solvento species, blue-violet cis-trans-cis-[Ru(OH2)2(RaaiR′)2](ClO4)2 [Raai R′=p-R-C6H4
N=N–C3H2–NN–1–R′, (1–3), abbreviated as N,N′-chelator, where N(imidazole) and N(azo) represent N and N′, respectively; R = H (a), OMe (b), NO2 (c) and R′ = Me (1/4/7/10), CH2CH3 (2/5/8/11), CH2Ph (3/6/9/12)] that have been reacted with NO2−in warm EtOH resulting in violet dinitro complexes of the type, Ru(NO2)2(RaaiR′)2 (7–9). The nitrite complexes are useful synthons of electrophilic nitrosyls, and on triturating the compounds, (7b–9b) with conc. HClO4 nitro-nitrosyl derivatives, [Ru(NO2)(NO)(OMeaaiR′)2](ClO4)2 (10b–12b) are isolated. The solution structure and stereoretentive transformation in each step have been established from 1H n.m.r. results. All the complexes exhibit strong MLCT transitions in the visible region. They are redox active and display
one metal-centred oxidation and successive ligand-based reductions. The redox potentials of Ru(III)/Ru(II) (E1/2M) of (10b–12b) are anodically shifted by ∼
∼0.2 V as compared to those of dinitro precursors, (7b–9b). The ν(NO) >1900 cm−1 strongly suggests the presence of linear Ru–NO bonding. The electrophilic behaviour of metal bound nitrosyl has been proved
in one case (12b) by reacting with a bicyclic ketone, camphor, containing an active methylene group and an arylhydrazone with an active methine
group, and the heteroleptic tris chelates thus formed have been characterised. 相似文献
13.
I. M. Chung H. Y. Park S. C. Chun J. J. Kim A. Ahmad 《Chemistry of Natural Compounds》2007,43(4):417-421
Three new compounds, 4-hydroxymethylene-7-(9,9,13-trimethylcyclohexyl)-heptanyl-3′,7′,7′-trimethylcyclohexa-2′,4′-dien-1′-oate
(1), 1-(n-hexadec-7-enoxy)-6-(n-octadecanoxy)-β-D-glucopyranoside (2), and (Z)-12-hydroxy-9-octadecenoic acid-12-β-D-glucopyranoside (3), along with the known compound hexacosanoic acid (4), were isolated and identified from the rice hulls of Oryza sativa. Their structures were elucidated by 1D and 2D NMR spectroscopic techniques (1H-1H COSY, 1H-13C HETCOR, DEPT) aided by EIMS, FABMS, HRFABMS, and IR spectra.
Published in Khimiya Prirodnykh Soedinenii, No. 4, pp. 344–347, July–August, 2007. 相似文献
14.
A coupling equation relating the quadrupole coupling constant (e2
Qq
zz
) to the asymmetry parameter (η) of the electric field gradient for a series of cobaltocenium derivatives (59Co NQR) is derived. The estimates of the correlation times of “slow” modulations of electron motions by tunneling processes
lie in the range from 10−12 to 10−14 s. This corresponds to the interval of the characteristic times of nuclear motions.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1919–1923, October, 2007. 相似文献
15.
Nizam M. El-Ashgar Issa M. El-Nahhal Mohamed M. Chehimi Michel Delamar Florence Babonneau Jacques Livage 《Journal of Sol-Gel Science and Technology》2007,41(1):3-10
A new insoluble solid functionalized ligand system bearing chelating ligand group of the general formula P-(CH2)3-N[CH2CONH(C6H4)NH2]2, where P represents [Si–O]
n
polysiloxane network, was prepared by the reaction of the immobilized diethyliminodiacetate polysiloxane ligand system, P-(CH2)3N(CH2CO2Et)2 with 1,2-diaminobenzene in toluene. 13C CP-MAS NMR, XPS and FTIR results showed that most ethylacetate groups (–COOEt) were converted into the amide groups (–N–C=O).
The new functionalized ligand system exhibits high capacity for extraction and removal of the metal ions (Fe3+, Co2+, Ni2+, Cu2+ and Zn2+) with efficiency of 95–97% after recovery from its primary metal complexes. This functionalized ligand system formed 1:1
metal to ligand complexes. 相似文献
16.
N. N. Il'chenko V. N. Britsun M. O. Lozinskii 《Theoretical and Experimental Chemistry》2005,41(5):284-289
The keto-enol-enethiol tautomerism in 3-oxo-3-R1-N-R2-propanethioamides under vacuum and in acetone was studied in terms of density functional theory. It was established that
the equilibrium depends on the structure of the 3-oxo-3-R1-N-R2-propanethioamides and on the nature of the solvent, but the most stable form is as a rule the keto form stabilized by an
intramolecular hydrogen bond.
__________
Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 41, No. 5, pp. 272–277, September–October, 2005. 相似文献
17.
P. I. Abronina L. V. Backinowsky A. A. Grachev S. L. Sedinkin N. N. Malysheva 《Russian Chemical Bulletin》2005,54(5):1287-1293
Methyl 2,4-di-O-benzoyl-α-D-mannopyranoside was used as a key intermediate in the synthesis of 3,6-branched mannopentaoside bearing one terminal D-[1-13C]mannopyranose residue, viz., methyl 6-O-[3,6-di-O-(α-D-mannopyranosyl)-α-D-mannopyranosyl)-3-O-{α -D-[1-13C]mannopyranosyl}-α-D-mannopyranoside.
Dedicated to Academician N. K. Kochetkov on the occasion of his 90th birthday.
__________
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1250–1255, May, 2005. 相似文献
18.
Comparative quantum chemical calculations of structural parameters, chemical shifts of 11B NMR spectra, and atomic charges in 10-vertex boron hydride anions [1-CB9H10]− and [1-B10H9N2]− were performed using the restricted Hartree-Fock method with the 6-31++G(D,P) basis set.
Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1853–1855, September, 2007. 相似文献
19.
The effects of La3+ on inward K+ channels at plasma membrane in vicia guard cells are investigated using the whole-cell patch-clamp recording mode. It is
shown that La3+ on both sides of plasma membrane blocks inward K+ currents in a concentration-dependent manner, indicating that La3+ binding sites may exist on both sides of plasma membrane in guard cells in vicia. The dose response is fitted by the Michaelis-Menten
relation characterized by an inhibitor constant K
i
of 2.56±0.25 μmol · L−1 (outside membrane) and (1.18±0.11)×10−15 mol · L−1 (inside membrane). Intracellular La3+ has much stronger inhibitory effect on inward K+ currents than extracellular La3+ does, suggesting there may exist stronger binding sites inside membrane than outside membrane. Since ion channel activities
of guard cells directly affect plant stomatal movement and water status, our results imply that rare earth elements might
have potential practical values in regulating plant water status and strengthening plant drought endurance. 相似文献
20.
The structure of galactomannans isolated from seeds of G. delavayi and G. aquatica was studied by 1H and 13C NMR spectroscopy. It was found that the galactomannans consisted mainly of β-1-4-bound mannopyranoses, a part of which was substituted on the C-6 hydroxyl by terminal units of α-galactopyranose.__________Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 12–13, January–February, 2005. 相似文献