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1.
The molecular structure of 23,24,25,26,27,29,30-heptamethyl-19,28-oxahexacyclo[15.13.18.017,18.013,14.08,9.05,10]tetracos-3-yl acetate III. Compound III C32H52O3 crystallizes in the monoclinic crystal system with the unit cell parameters a = 13.265(15) ?, b = 6.481(7) ?, c = 32.274(4) ?, β = 99.333(2)°, space group C2, Z = 4, d = 1.176 g/cm3.
Original Russian Text Copyright ? 2009 by N. I. Medvedeva, O. B. Flechter, and A. A. Korlyukov
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Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 2, pp. 399–401, March–April, 2009. 相似文献
2.
L. T. Eremenko L. B. Romanova M. E. Ivanova E. L. Ignat'eva 《Russian Chemical Bulletin》1993,42(4):770-771
Dialkyl pentacyclo[4.2.0.02,5.03,8.04,7]octane-1,4-dicarboxylates (where alkyl is methyl,iso-propyl, 2-fluoro-2,2-dinitroethyl, or 2,2,2-trinitroethyl) were prepared in high yields by O-alkylation of 1,4-cubanedicarboxylic acid with the corresponding monoalkyl sulfates.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 801–802, April, 1993. 相似文献
3.
As part of a programme to synthesize thione derivatives with pentacyclo[5.4.0.02,6.03,10.05,9]undecane moieties it was decided to sulfurize the monoacetal 6 of pentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-dione 2. Unexpectedly the diol 9 was isolated as the product. 相似文献
4.
Pentacyclo[5.4.0.02,6.03,10.05,9]undecan-8-one 1 is readily sulfurated into pentacyclo[5.4.0.02,6.03,10.05,9]undecane-8-thione 2 with Lawesson’s reagent in dry THF. Upon standing at ambient temperature the thione 2 formed the corresponding thio-dimer 3 within 10 days. When the thio-dimer 3 was exposed to oxygen and ultraviolet light an unexpected photochemical oxidation and rearrangement took place to form the stable disulfenate 5. 相似文献
5.
I. E. Smirnova E. V. Tret’yakova O. B. Kazakova Z. A. Starikova I. V. Fedyanin 《Journal of Structural Chemistry》2009,50(2):378-380
Synthesis is performed and the molecular structure is analyzed of methyl-18R-13-isopropyl-10a,7-dimethyl-4-oxo-1-oxahexacyclo[12.4.0.05a,4a.013,12.01,1a.010a,6a]heneicosane-7-carboxylate II. Compound II C27H40O4 crystallizes in orthorhombic symmetry with cell parameters: a = 11.9915(15) ?, b = 12.1674(16) ?, c = 15.8094(17) ?, P212121, Z = 4, d = 1.234 g/cm3.
Original Russian Text Copyright ? 2009 by I. E. Smirnova, E. V. Tret’yakova, O. B. Kazakova, Z. A. Starikova, and I. V. Fedyanin
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Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 2, pp. 391–392, March–April, 2009. 相似文献
6.
Distribution and accumulation of antimony in plants in the super-large Sb deposit areas, China 总被引:1,自引:0,他引:1
Antimony (Sb) distribution and accumulation in plants in Xikuangshan Sb deposit area, the only one super-large Sb deposit in the world, Hunan, China were investigated. Results show that soils were severely polluted with the average Sb concentrations up to 5949.20 mg kg− 1. Sb widely occurred in 34 plants with various concentrations ranging from 3.92 mg kg−1 to 143.69 mg kg− 1, Equisetaceae family has the highest concentration (98.23 mg kg− 1) while Dryopteridacea family has the lowest one (6.43 mg kg− 1). H. ramosissima species of Equisetaceae family had the highest Sb average concentration of 98.23 mg kg− 1 and P. vittata species of Pteridaceae family showed advantage of accumulating Sb from the contaminated environment (Biological Accumulation Coefficient, BAC = 0.08). Almost all species enriched Sb in their upground part such as shoot, leaf and flower (Biological Transfer Coefficient, BTC > 1), which may attribute to the high acropetal coefficient and Sb transformation from the atmosphere to the plants. P. phaseoloides and D. indicum showed predominantly accumulation of Sb in the upground part with BTC of 6.65 and 5.47, respectively.From the low bioavailable fraction in soils and weak relationship between total soil concentrations in soils and plants, it seems that the Sb bioavailability was limited and varied with different soil sites as well as plant species. Those observations would be significant to the phytoaccumulation and phytoremediation of plants and ecological and environmental risk assessment in Sb contaminated areas. 相似文献
7.
I. E. Smirnova E. V. Tret’yakova O. B. Kazakova Z. A. Starikova 《Journal of Structural Chemistry》2009,50(2):381-383
Synthesis is performed and the molecular structure is analyzed of methyl-4-anti-hydroxyimino-1-dioxolano-13-isopropyl-10a,7-dimethylpentacyclo[10b.8.5.04b,10b.06a,10a.01a,4a]icos-14-ene-7-carboxylate IIa. Compound IIa C27H40O4 crystallizes in monoclinic symmetry with cell parameters: a = 13.785(13) ?, b = 7.302(7) ?, c = 13.817(13) ?, β = 94.799(19)°, space group P2(1), Z = 2, d = 1.164 g/cm3.
Original Russian Text Copyright ? 2009 by I. E. Smirnova, E. V. Tret’yakova, O. B. Kazakova, and Z. A. Starikova
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Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 2, pp. 393–395, March–April, 2009. 相似文献
8.
The present paper reports a.c. impedance spectroscopic studies on adsorption of guanidonium (G+) and N,N-dimethylguanidonium (DMG+) resonant cations at Pt(1 0 0) single-crystal surface. The resulted information provided confirmation of the role of electrosorption of the above-mentioned molecule–ions through evaluation of the associated charge-transfer resistances and capacitances for the Pt(1 0 0) plane in 0.5 M H2SO4. These results also provided support for the interfacial ion-pairing mechanism that had been based on the voltammetric and in situ FTIR spectroscopic results published earlier. 相似文献
9.
N. Lakshminarasimhan 《Journal of solid state chemistry》2004,177(10):3536-3544
Eu3+ luminescence is studied in apatite-related phosphate BiCa4(PO4)3O. Compositions of the formula Bi1−xEuxCa4(PO4)3O [x=0.05, 0.1, 0.3, 0.5, 0.8 and 1.0] are synthesized and they are isostructural with parent BiCa4(PO4)3O. Room temperature photoluminescence shows the various transitions 5D0→7FJ(=0,1,2) of Eu3+. The emission results of compositions with different Eu3+ content show the difference in site occupancy of Eu3+ in Bi1−xEuxCa4(PO4)3O. The intense 5D0-7F0 line at 574 nm for higher Eu3+ content is attributed to the presence of strongly covalent Eu-O bond that is possible by substituting Bi3+ in the Ca(2) site. This shows the preferential occupancy of Bi3+ in Ca(2) site and this has been attributed to the 6s2 lone pair electrons of Bi3+. This is further confirmed by comparing the emission results with La0.95Eu0.05Ca4(PO4)3O. 相似文献
10.
SrZnO2:Eu3+ has been synthesized by solid-state reaction and its photoluminescence in ultraviolet (UV)-vacuum ultraviolet (VUV) range was investigated. The broad bands around 254 nm are assigned to CT band of Eu3+-O2−. With the increasing of Eu3+ concentration, Eu3+ could occupy different sites, which leads to the broadening of CT band. A sharp band is observed in the region of 110-130 nm, which is related to the host absorption. The phosphors emit red luminescence centered at about 616 nm due to Eu3+5D0→7F2 both under 254 and 147 nm, but none of Eu2+ blue emission can be observed. 相似文献
11.
A facile method based on high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (HPLC/(+)ESI-MSn) has been established for the analysis of polyoxypregnane glycosides in the stems of Marsdenia tenacissima. The data reveals the ability of MSn in the structural elucidation of polyoxypregnane glycosides including the nature of the polyoxypregnane core, the kinds of the substituents and the types of sugar residues. Offline Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) is also performed to assign accurate elemental compositions. In this study, eighteen polyoxypregnane glycosides have been investigated. Among these components, five compounds are unambiguously identified as Marsdenoside K, Tencissoside A, B, C and D; two compounds are established as novel compounds based on mass spectral data; and the other eleven compound's structures are tentatively proposed. Furthermore, breakdown curves are constructed to distinguish five pairs of isomers among these eighteen compounds. As far as our knowledge, this is the first report on identification of polyoxypregnane glycosides in the stems of M. tenacissima by HPLC/ESI-MSn directly, which could save time and material consuming efforts in traditional phytochemistry analyses. 相似文献
12.
Reductive debenzylation of hexabenzylhexaazaisowurtzitane — the key step of the synthesis of polycyclic nitramine hexanitrohexaazaisowurtzitane 总被引:1,自引:0,他引:1
Main features of the reductive debenzylation of 2,4,6,8,10,12-hexabenzyl-2,4,6,8,10,12-hexaazaisowurtzitane were studied.
This process is the key step of the synthesis of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo[5.5.0.03,11.05,9]dodecane (hexanitrohexaazaisowurtzitane, CL-20), a compound with unique energetic and explosive characteristics. The use
of the latter is restricted so far by the high cost of the two-step process of debenzylation during which the compound is
rapidly deactivated. The expensive Pd/C catalyst is deactivated in the first step of the process, which limits the use of
this polycyclic nitramine. The influence of the solvent nature; loadings of the reactants, catalyst, and cocatalyst; the hydrogen
pressure and reaction temperature on the general features of the process and the yield of the target precursor of CL-20 was
studied.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2290–2295, December, 2007. 相似文献
13.
Dimethyl dihydro-1,2,4,5-tetrazine-3,6-dicarboxylate can exist either in 1,2- or 1,4-dihydro tautomeric forms. The 15N NMR spectra of dimethyl dihydro-1,2,4,5-tetrazine-3,6-dicarboxylate were measured at the 15N natural abundance level as well as in 15N doubly labelled selectively and in 15N completely labelled compounds (20% 15N). The J(15N,15N) value was determined in 15N completely labelled compounds (20% 15N) using 1D 15N INADEQUATE and was found to be 12.2 ± 0.2 Hz in deuteriochloroform, acetonitrile-d3, DMSO-d6 and CD3OH. Very similar 15N chemical shifts and 1J(15N,1H) values were also observed in all the solvents. This indicates that compound 1 exists completely in the 1,4-dihydro tautomeric form (i.e., as dimethyl 1,4-dihydro-1,2,4,5-tetrazine-3,6-dicarboxylate) in all the solvents tested. 相似文献
14.
CeO2-γ-Al2O3 mixed oxides have been prepared by using both co-precipitation and impregnation methods followed by calcination at 650°C and investigated by 27Al MAS NMR, powder X-ray diffraction and temperature programmed reduction techniques to understand the nature of chemical interaction existing between CeO2 and γ-Al2O3. The 27Al NMR spectra of CeO2-containing samples showed an additional peak placed at 40 ppm along with the two peaks at 68 and 6 ppm which originate from the tetrahedrally and octahedrally coordinated Al3+ ions present in γ-Al2O3. As the concentration of CeO2 in the mixed oxide increased, the intensity of the 40 ppm peak increased and this was the prominent peak for CeO2-rich mixed oxide samples. The origin of this 40 ppm peak is discussed and it is inferred that this peak is due to Al3+ ions, which are present in CeO2 lattice, forming a solid solution. 相似文献
15.
I.D. Sadekov V.I. Minkin A.V. Zakharov A.G. Starikov G.S. Borodkin S.M. Aldoshin G.V. Shilov 《Journal of organometallic chemistry》2005,690(1):103-116
A series of N-arylimines of β-tellurocyclohexenals 11 have been synthesized and the molecular and crystal structures of the compounds 11a-e and also β-(dimethyltelluronium)cyclohexenal perchlorate 12 studied by X-ray crystallography. All the compounds contain strong intramolecular coordination N → Te (O → Te) bonds of the hypervalent type. In 11a-e, the lengths of the N → Te bonds are within the range of 2.690-2.147 Å and are 1.0-1.5 Å shorter than the sum of the van der Waals radii of respective atoms. In the N-arylimines 11b-e with the electronegative groups attached to the tellurium center, the lengths of the N → Te bonds are very close to that characteristic of a standard covalent N-Te bond. The experimental observed geometries are well reproduced by the DFT calculations performed at B3LYP/LanL2DZ level of approximation. The energies of the intramolecular coordination N → Te bonds vary from 23 kJ mol−1 for 11a to 119 kJ mol−1 for 11e. The calculated energy of the O → Te bond in 12 was found to be 50 kJ mol−1. The 125Te NMR chemical shifts of compounds 11 span the wide range of 734.3-1622.4 ppm. The largest downfield 125Te NMR chemical shifts are observed in the case of the compounds 11e, f in which the most electronegative atoms are attached to the tellurim centers. 相似文献
16.
Dengfeng Cheng Lan Zhang Mingwei Wang Gucai Li Yongxian Wang 《Journal of fluorine chemistry》2007,128(3):196-201
Vasoactive intestinal peptide (VIP) receptors are expressed on various tumor cells in much higher density than somatostatin receptors, which provides the basis for radiolabeling VIP as tumor diagnostic agent. However, fast proteolytic degradation of VIP in vivo limits its clinical application. With the aim to develop and evaluate new ligands for depicting the VIP receptors with positron emission tomography (PET), the structure modified [R8,15,21, L17]-VIP analog was radiolabeled with 18F using two different methods. With the first method, N-4-[18F]fluorobenzoyl-[R8,15,21, L17]-VIP ([18F]FB-[R8,15,21, L17]-VIP 7) was produced in a decay-corrected radiochemical yield (RCY) of 33.6 ± 3%, a specific radioactivity of 255 GBq/μmol (n = 5) within 100 min in four steps. Similarly, N-4-[18F](fluoromethyl)-benzoyl-[R8,15,21, L17]-VIP ([18F]FMB-[R8,15,21, L17]-VIP 8) was synthesized in a RCY of 34.85 ± 5%, a specific radioactivity of 180 GBq/μmol (n = 5) within 60 min in only one step. The two products 7 and 8 were both shown good stability in HSA. Moreover, the low bone uptakes of 7 and 8 in vivo of mice showed good defluorination stability. 相似文献
17.
Manfredo Hörner Gelson Manzoni de Oliveira Janaina Sartori Bonini Herton Fenner 《Journal of organometallic chemistry》2006,691(4):655-658
3-(2-fluorophenyl)-1-(3-nitrophenyl)triazene reacts with mercury(II) acetate in tetrahydrofuran in the presence of 2,2′-bipyridilamine to give yellow crystalline blocks of polymeric {HgII[NNN(PhR)2]2}n (R = NO2, F). The new triazenide complex belongs to the triclinic space group . In a molecule of {HgII[NNN(PhR)2]2} two deprotonated 1,3-diaryl-substituted triazenide ligands are coordinated in an opposite way to one Hg(II) ion by means of primary and secondary bonds. The Hg(II) ions are placed on the inversion centers of translation operated {Hg[NNN(PhR)2]2} moieties which are stacked along the crystallographic a-axis forming infinite unidimensional chains linked through metalocene alike Hg-η2,η2-arene π-interactions. 相似文献
18.
Matic Lozinšek Evgeny Goreshnik Anton Meden Gašper Tav?ar 《Journal of solid state chemistry》2009,182(10):2897-2903
In the system BaF2/BF3/PF5/anhydrous hydrogen fluoride (aHF) a compound Ba(BF4)(PF6) was isolated and characterized by Raman spectroscopy and X-ray diffraction on the single crystal. Ba(BF4)(PF6) crystallizes in a hexagonal space group with a=10.2251(4) Å, c=6.1535(4) Å, V=557.17(5) Å3 at 200 K, and Z=3. Both crystallographically independent Ba atoms possess coordination polyhedra in the shape of tri-capped trigonal prisms, which include F atoms from BF4− and PF6− anions. In the analogous system with AsF5 instead of PF5 the compound Ba(BF4)(AsF6) was isolated and characterized. It crystallizes in an orthorhombic Pnma space group with a=10.415(2) Å, b=6.325(3) Å, c=11.8297(17) Å, V=779.3(4) Å3 at 200 K, and Z=4. The coordination around Ba atom is in the shape of slightly distorted tri-capped trigonal prism which includes five F atoms from AsF6− and four F atoms from BF4− anions. When the system BaF2/BF3/AsF5/aHF is made basic with an extra addition of BaF2, the compound Ba2(BF4)2(AsF6)(H3F4) was obtained. It crystallizes in a hexagonal P63/mmc space group with a=6.8709(9) Å, c=17.327(8) Å, V=708.4(4) Å3 at 200 K, and Z=2. The barium environment in the shape of tetra-capped distorted trigonal prism involves 10 F atoms from four BF4−, three AsF6− and three H3F4− anions. All F atoms, except the central atom in H3F4 moiety, act as μ2-bridges yielding a complex 3-D structural network. 相似文献
19.
Ignacio Fernández Philip D. Bolton Matthew G. Davidson Fernando López-Ortiz 《Journal of organometallic chemistry》2004,689(11):1890-1896
The addition of LiBun to a toluene solution of Ph2P(O)N(CH2Ph)CH31 and 2,6-di-tert-butyl-4-methylphenol 5 leads to the formation of the mixed dimer [(Ph2P(O)N(CH2Ph)CH3) · LiOC6H2-2,6-{C(CH3)3}2-4-CH3) · C7H8]26. The single crystal X-ray structure shows that two lithium aryloxide moieties dimerize giving rise to a Li2O2 core in which each lithium atom is additionally coordinated to a phosphinamide 1 ligand. The multinuclear magnetic resonance study (1H, 7Li, 13C, 31P) indicates that the solid-state structure is preserved in toluene solution. Complex 6 may be considered as a model for the pre-complexation step preceding the metalation of phosphinamides by an organolithium base. 相似文献