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1.
V. K. Voronkova R. T. Galeev S. Shova G. Novitchi C. I. Turta A. Caneschi D. Gatteschi J. Lipkowski Yu. A. Simonov 《Applied magnetic resonance》2003,25(2):227-247
New compounds, [Cu3Ln2(ClCH2COO)12(H2O)8]·2H2O with Ln = Nd3+ (I), Sm3+ (II), Pr3+ (III), built up of pentanuclear clusters were synthesized and studied by means of X-ray analysis and electron paramagnetic
resonance (EPR). X-ray data show that all compounds are isostructural and the pentanuclear clusteres may be considered as
a linear system with alternating Cu(II) and Ln(III) ions: Cu(2)-L1-Ln-L2-Cu(1)-L2-Ln-L2-Cu(2) with L1 and L2 being bridging fragments and Cu(1) and Cu(2) being structurally nonequivalent copper complexes. EPR studies demonstrate that
in the temperature range of 100–293 K the signals due to only one type of the copper complexes are observed in the spectra
of I–III. AtT<100 K the spectral temperature dependence is nontrivial. AtT<30 K new signals are detected in the spectra of I and II. The temperature dependence of the EPR spectra is interpreted under
the assumption that the parameter of the exchange interaction Cu(2)-Ln considerably exceeds the parameter of the interaction
Cu(1)-Ln. EPR spectra are calculated for the fragments of five paramagnetic centers in the frames of the model taking into
account the nonequivalence of two copper complexes, short longitudinal and transverse paramagnetic relaxation times of the
rare-earth ions at room temperature and the change of the relaxation rates when the temperature decreases. The results of
the calculations show that it is possible to obtain information about the interactions in the system on the basis of the analysis
of the temperature dependence of the EPR spectra of the central copper complex. The parameter of the isotropic part of the
exchange interaction between copper and neodymium ions (for the interaction Cu(2)-Nd) is estimated as about 15 cm−1. A considerable rearrangement of the spin states when the temperature changes is found for all complexes. 相似文献
2.
F. Bottino P. Finocchiaro J. Lipkowski A. Mamo S. Pappalardo K. Suwinska 《Journal of inclusion phenomena and macrocyclic chemistry》1991,11(1):41-48
The crystal and molecular structure of the title compound, C51H57N3O6S3·CH2Cl2 has been determined by single crystal X-ray analysis and refined to anR-value of 0.069 for 1032 reflections. The crystal is trigonal, space groupR3, witha = 21.255(7),c = 11.317(4), andZ = 3. One molecule of dichloromethane used as solvent is enclathrated in the crystal lattice. 相似文献
3.
Lewiński J Marciniak W Lipkowski J Justyniak I 《Journal of the American Chemical Society》2003,125(42):12698-12699
Studies on the reaction of zinc alkyls with O2 are reported which demonstrate that the selective oxygenation of organozinc compound is viable. The reaction of [EtZn(azol)]n (azol = deprotonated 1-aziridineethanol) with an excess of dry O2 in toluene affords the zinc ethylperoxide [EtOOZn(azol)]2[EtZn(azol)]2, while the analogous reaction between Me2Zn and O2 results in the isolation of the Me6Zn7(OMe)8 cluster in high yield. 相似文献
4.
Ryabov AD Otto S Samuleev PV Polyakov VA Alexandrova L Kazankov GM Shova S Revenco M Lipkowski J Johansson MH 《Inorganic chemistry》2002,41(16):4286-4294
Structural and mechanistic aspects of orthoplatination of acetophenone and benzaldehyde oximes by the platinum(II) sulfoxide and sulfide complexes [PtCl(2)L(2)] (2, L = SOMe(2) (a), rac-SOMePh (b), R-SOMe(C(6)H(4)Me-4) (c), and SMe(2) (d)) to afford the corresponding platinacycles cis-(C,S)-[Pt(II)(C(6)H(3)-2-CR'=NOH-5-R)Cl(L)] (3, R, R' = H, Me) have been investigated. The reaction of acetophenone oxime with sulfoxide complex 2a in methanol solvent occurs noticeably faster than with sulfide complex 2d due to the fact that the sulfoxide is a much better platinum(II) leaving ligand than the sulfide. Evidence is presented that the orthoplatination is a multistep process. The formation of unreactive dichlorobis(N-oxime)platinum(II) cations accounts for the rate retardation by excess acetophenone oxime and suggests the importance of pseudocoordinatively unsaturated species for the C-H bond activation by Pt(II). A comparative X-ray structural study of dimethyl sulfoxide platinacycle 3b (R = R' = Me) and its sulfide analogue 3e (R = H, R' = Me), as well as of SOMePh complex 3c (R = H, R' = Me), indicated that they are structurally similar and a sulfur ligand is coordinated in the cis position with respect to the sigma-bound phenyl carbon. The differences concern the Pt-S bond distance, which is notably longer in the sulfide complex 3e (2.2677(11) A) as compared to that in sulfoxide complexes 3b (2.201(2)-2.215(2) A) and 3c (2.2196(12) A). Whereas the metal plane is practically a plane of symmetry in 3b due to the H-bonding between the sulfoxide oxygen and the proton at carbon ortho to the Pt-C bond, an S-bonded methyl of SOMePh and SMe(2) is basically in the platinum(II) plane in complexes 3c and 3e, respectively. There are intra- and intermolecular hydrogen bond networks in complex 3b. An interesting structural feature of complex 3c is that the two independent molecules in the asymmetric unit of the crystal reveal an extremely short Pt-Pt contact of 3.337 A. 相似文献
5.
Roman Luboradzki Janusz Lipkowski Yurii A. Simonov Marina S. Fonari Edward V. Ganin Arkadii A. Yavolovskii 《Journal of inclusion phenomena and macrocyclic chemistry》1995,23(3):181-193
An X-ray—diffraction study is reported for two molecular complexes containing 3,4-diamino-1,2,5-oxadiazole as guest (G) with 18-crown-6 (18-C-6) andcis-anti-cis-dicyclohexano-18-crown-6 (DCH-6B) as host. Both complexes are of the polymeric-chain structure with the guest molecule bridging two crown neighbours. ComplexI: [18-C-6*G*H2O], 111, monoclinic,P21/n,a=8.171(1),b=15.042(2),c=16.209(6) Å, =101.15(2)°, finalR-factor 0.068. ComplexII: [DCH-6B*G], 11, monoclinicC2/c,a=21.212(4),b=9.380(2),c=13.049(3) Å, =108.61(3)°, finalR 0.047. 相似文献
6.
A. Yu. Manakov J. Lipkowski K. Suwinska M. Kitamura 《Journal of inclusion phenomena and macrocyclic chemistry》1996,26(1-3):1-20
Single crystal X-ray structures of clathrates of -[Ni(NCS)2(4-methylpyridine)4] with furan, tetrahydrofuran, benzene + ethanol, methylene chloride, and methylcellosolve as guests molecules are reported. The location of the guest molecule in the partially decomposed clathrate with methylene chloride was defined by X-ray diffraction and compared with the fully occupied one. The host lattices of all clathrates studied are tetragonal (I41/a) and do not differ significantly from typical -phase clathrates of [M(NCS)2(4-methylpyridine)4] (M = divalent metal cation). Arrangements of guest molecules represent different types of packing: one type of guest molecule occupies both possible types of positions, two different guest molecules occupy different positions, with only one type of positions occupied by one type of guest molecule. Possible stoichiometries of clathrates with -type lattices are discussed.Presented at the Sixth International Seminar on Inclusion Compounds, Istanbul, Turkey, 27–31 August 1995. 相似文献
7.
Synthesis and Crystal Structure of Supramolecular Adducts of Macrocyclic Cavitand Cucurbituril with Chromium(III) and Nickel(II) Aqua Complexes 总被引:1,自引:0,他引:1
Samsonenko D. G. Geras'ko O. A. Mit'kina T. V. Lipkowski J. Virovets A. V. Fenske D. Fedin V. P. 《Russian Journal of Coordination Chemistry》2003,29(3):166-174
Supramolecular compounds {[Cr(H2O)6](C36H36N24O12)}(NO3)3 · 13H2O (I) and {[Ni(H2O)6]2(C36H36N24O12)}(SO4)2 · 16H2O (II) were obtained from aqueous solutions of chromium nitrate or nickel sulfate and the macrocyclic cavitand cucurbituril. According to X-ray diffraction analysis data, the cucurbituril molecule is closed from both sides by metal aqua complexes due to the formation of hydrogen bonding between the cucurbituril CO groups and aqua ligands. Compound I has a chain structure, while the structure of compound II is layered. Modes of cucurbituril coordination, depending on the size and charge of the metal cation, are discussed. 相似文献
8.
Burgess I Li M Horswell SL Szymanski G Lipkowski J Satija S Majewski J 《Colloids and surfaces. B, Biointerfaces》2005,40(3-4):117-122
A model biological membrane was formed by fusion of mixed cholesterol and DMPC (dimyristoylphosphatidylcholine) phospholipid vesicles onto a gold-coated quartz support. The gold surface was charged and the influence of the charge at the solid support on the structure and integrity of the phospholipid bilayer was investigated using the specular reflection of neutrons and electrochemical measurements. When the surface charge density is close to zero, the lipid vesicles fuse directly on the surface to form a bilayer with a small number of defects and hence low water content. When the support's surface is negatively charged the film swells and incorporates water due to the field driven poration of the membrane. When the charge density is more negative then -8 microC cm(-2) the bilayer is detached from the metal surface. However, it remains in close proximity to the metal electrode, suspended on a thin cushion of water. The film thicknesses, calculated from neutron reflectivity, have allowed us to determine the tilt angle of the lipid molecules as a function of the support's charge density. The lipid molecules are tilted 55 degrees from the surface normal at zero charge density but become significantly more perpendicular (30 degrees tilt angle) at charge densities more negative than -8 microC cm(-2). The tilt angle measurements are in very good agreement with previous IR studies. This paper describes the highlights of a more in-depth study which is fully described in [1]. 相似文献
9.
T. V. Rodionova Yu. A. Dyadin K. A. Udachin Ya. Lipkowski K. Suwinska 《Journal of Structural Chemistry》1995,36(3):458-464
Phase diagrams of some binary aqueous systems with tetraalkylammonium fluorides are examined. The size of the hydrophobic
moiety of the guest is consecutively varied in the series (i-C5H11)4−k(C4H9)kNF (k=0, 1, 2, 3) by replacing bulky isoamyl radicals with n-butyl radicals. Changes in clathrate formation caused by variations
of the sizes and forms of guests are analyzed in the series (i-C5H11)k−4(C4H9)kNF−H2O (k=0, 1, 2, 3, 4). All tetraisoamylammonium fluoride hydrates are more stable than other hydrates of this series. The stability
of the compounds increases due to the fact that the isoamyl radicals use the host cavities more effectively than the butyl
radicals. In all hydrates of the series, tetragonal structures-I (TS-I), which were earlier thought typical only for hydrates
of tetrabutylammonium salts, are formed. Hydrates of the orthorhombic system are formed until three isoamyl radicals have
been replaced by butyl radicals. Hydrates with 26–28 water molecules (mp 27.4–34.6°C) are the most stable hydrates of the
series, except for i-AmBu3NF·25.9 H2O, melting 0.3°C lower than the tetragonal hydrate in the same system. All compounds are defined chemically, and for some
of them crystal data are given.
Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Institute of Physical Chemistry, Polish Academy
of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 3, pp. 501–508, May–June, 1995.
Translated by L. Smolina 相似文献
10.
Annia H. Kycia Kallum Koczkur J. Jay Leitch Jacek Lipkowski Vlad Zamlynny Michael W. P. Petryk 《Analytical and bioanalytical chemistry》2013,405(5):1537-1546
Polarization modulation–infrared reflection absorption spectroscopy (PM-IRRAS) was employed to analyze two unique samples: (1) an industrially prepared alkoxysilane-pretreated aluminum alloy (AA6111) in the absence and presence of a ~600-nm-thick lubricant coating and (2) a chemical warfare agent simulant, triethyl phosphate (TEP), on glass. For the pretreated aluminum samples, PM-IRRAS spectra were analyzed for three distinct regions; the SiO stretching vibration around 1120 cm?1, the NH2 bending mode at ~1600 cm?1 and the CH stretching region around 2900 cm?1. Our results showed that increasing the curing temperature (from 55 to 100 °C) improved the overall extent of cross-linking within the siloxane network. In addition, the spectra of lubricant (top coating) and the underlying siloxane layer for the aluminum samples with lubricant were collected for the same sample. Our results show that the nature of the siloxane film remains intact and unaltered after deposition of the lubricant top-coat. For detection of TEP on glass, the band at 1268 cm?1, corresponding to the P═O vibration, was monitored. A droplet of TEP solution in dichloromethane was deposited on glass. After solvent evaporation had occurred, the intensity of the P═O vibration band was used to construct calibration curves to determine the experimental limit of detection, which was found to be ~200 μg for TEP on glass. Figure
Schematic of a akoxysilane network and PM-IRRAS spectrum of the alkoxysilane film at aluminum surface 相似文献