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161.
Pulacchini S Nasser R Sibbons KF Motevalli M Hawkes GE Kroemer RT Bento ES Watkinson M 《Organic & biomolecular chemistry》2003,1(22):4058-4063
Investigations into the conformational behaviour of macrocyclic ligands 5 and 6 derived from (R,R)-1,2-diaminocyclohexane have been undertaken using molecular modelling, single crystal X-ray diffraction and variable temperature 1H NMR spectroscopy. These have revealed that the lowest energy conformers in both cases do not possess the expected C2-element of symmetry, which can only be accessed at higher temperatures. Instead both molecules exist as C1-conformers at room temperature and in the solid state. In solution a range of dynamic exchange processes is observed which result, in part from the inherent strain in these fused bicyclic systems. An unexpected but characteristic feature of the C1-symmetric conformers is highlighted by the presence of a signal at unexpectedly low field in their 1H NMR spectra due to the interaction of two of the sulfonyl oxygen atoms with one of the bridgehead hydrogen atoms. 相似文献
162.
New nanocomposite materials based on polyurethane intercalated into organoclay layers have been synthesized via in situ polymerization. The syntheses of polyurethane–organoclay hybrid films were carried out by swelling the organoclay [12‐aminododecanoic acid montmorillonite] into different kinds of diols followed by addition of diisocyanate then casting in a film. The homogeneous dispersion of MMT in the polymer matrix is evidenced by scanning electron microscope and x‐ray diffraction, which showed the disappearance of the peak characteristic to d001 spacing. It was found that the presence of organoclay has improved the thermal, solvent resistance and mechanical properties. Also, the tensile strength is increased with increasing the organoclay contents to 20% by the ratio 182% related to the PU with 0% organoclay. On the contrary, the elongation has decreased with increasing the organoclay contents. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
163.
Khorasani-Motlagh M Safari N Noroozifar M Saffari J Biabani M Rebouças JS Patrick BO 《Inorganic chemistry》2005,44(22):7762-7769
Three new verdoheme analogues with weakly coordinating anions, [OEOPFe(II)X], where OEOP is the monoanion of octaethyloxoporphyrin and X = PF(6), ClO(4), and BF(4), have been synthesized and characterized by spectroscopic methods. (1)H NMR spectroscopy reveals that the [OEOPFe(II)X] species are paramagnetic, and the iron is five-coordinate (S = 2). The oxidation of [OEOPFe(II)PF(6)] with dioxygen yields [(OEOPFe)(2)O](PF(6))(2). The structure of (mu-oxo)bis[(octaethyloxoporphinato)iron(III)] has been determined by X-ray diffraction analysis. The eight Fe-N bond distances have an average value of 2.077(3) Angstroms. The oxygen atom sits on the inversion center, and the average axial Fe-O bond length is 1.756(3) Angstroms. The average displacement of the iron(III) atom from the mean porphinato core is 0.60 Angstroms. Crystal data: crystal system, monoclinic; a = 8.7114(10) Angstroms; b = 26.102(4) Angstroms; c = 15.8323(14) Angstroms; beta = 104.134(6) degrees ; space group P2(1)/c; V = 3491.1(7) Angstroms (3); Z = 2; R1 = 0.0546, wR2 =0.1145 for data with I > 2sigma(I). 相似文献
164.
Koomen JM Zhao H Li D Nasser W Hawke DH Abbruzzese JL Baggerly KA Kobayashi R 《Rapid communications in mass spectrometry : RCM》2005,19(12):1624-1636
A peptide targeting method has been developed for diagnostic protein discovery, which combines proteolytic digestion of fractionated plasma proteins and liquid chromatography coupled to electrospray time-of-flight mass spectrometry (LC/ESI-TOFMS) profiling. Proteolysis prior to profiling overcomes molecular weight limitations and compensates for the poor sensitivity of matrix-assisted laser desorption/ionization (MALDI) protein profiling. LC/MS increases the peak capacity compared to crude fractionation techniques or single sample MALDI analysis. Differentially expressed peptides are targeted in the mass chromatograms using bioinformatic techniques and subsequently sequenced with MALDI tandem MS. In a model study comparing pancreatic cancer patients to controls, 74% of the peptide targets were successfully sequenced. This profiling method was superior to previous experiments using single sample MALDI analysis for protein profiling or proteolytic peptide profiling, because more potential protein markers were identified. 相似文献
165.
The automatic method is based on the ternary complex formed with EDTA and Tiron. The method is satisfactory or quantifying 0.1–1.2 μg ml?1 dysprosium under conditions similar to those used for terbium. The effect of other lanthanides, yttrium, thorium, and dioxouranium(VI) on the fluorescence intensity is described; the main interference is from terbium(III). 相似文献
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Iodotrimethylsilane facilitates the rapid lactonization of alcohol ester 2 under remarkably mild conditions. 相似文献