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排序方式: 共有151条查询结果,搜索用时 250 毫秒
1.
The synthesis and properties of perchlorobi-9-fluorenylidene, a highly twisted ethylene, are reported. It is a diamagnetic chlorocarbon. 相似文献
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Ballester P Costa A Castilla AM Deyà PM Frontera A Gomila RM Hunter CA 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(7):2196-2206
Three isomeric zinc bisporphyrins have been prepared by covalently linking together two aminoporphyrins with an isophthalic acid derivative. The porphyrins differ in the substitution pattern on the meso phenyl groups, that is, ortho, meta, or para. Titrations carried out by UV-visible and 1H NMR spectroscopy have been used to map out the stabilities and the stoichiometries of the complexes formed with 1,4-diazabicyclo[2.2.2]octane (DABCO) in chloroform. The ortho- and meta-substituted bisporphyrins form 1:1 intramolecular sandwich complexes. The para-substituted bisporphyrin cannot adopt the cofacial conformation required for this type of complex and forms a higher order 2:2 intermolecular assembly, which is stable over a wide range of DABCO concentrations. 相似文献
5.
High-performance liquid chromatographic determination of naltrexone in plasma of hemodialysis patients 总被引:1,自引:0,他引:1
Kambia K Bah S Dine T Azar R Odou P Gressier B Luyckx M Brunet C Ballester L Cazin M Cazin JC 《Biomedical chromatography : BMC》2000,14(3):151-155
A simple, sensitive, selective and reliable reversed-phase high-performance liquid chromatographic (HPLC) method with UV detection is described for the determination of naltrexone in plasma samples. Naltrexone and the internal standard, naloxone, were isolated from plasma either with a liquid-liquid extraction method using ethyl acetate or with a solid-phase extraction method using Sep-Pack C18 cartridge before chromatography. The extracts were dried under a stream of nitrogen and the samples were reconstituted in the mobile phase, then 20 microL were injected on a Waters Symmetry C18 column (5 microm particle size, 4.6 x 150 mm). The mobile phase consisted of 0.06% triethylamine (pH 2.8)-acetonitrile (92:8, v/v) pumped at 1 mL/min. The peak-area ratio versus plasma concentration was linear over the range of 10-500 ng/mL and the detection limit was less than 8 ng/mL. Quantification was by ultra-violet detection at 204 nm. The present method was applied to the determination of the plasma concentration of naltrexone in dialyzed patients. Patients (n = 8) with severe generalized pruritus received 50 mg of naltrexone orally per day for 2 weeks. The variability in the therapeutic response in treated patients required plasma concentration investigations of this opioid antagonist. 相似文献
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Ballester P Capó M Costa A Deyà PM Frontera A Gomila R 《Molecules (Basel, Switzerland)》2004,9(5):278-286
A dinuclear self-assembled cationic macrocycle based on Pt(II)-N(pyridine) coordinative bonds and having competitive triflate anions, as metal counterions, is used in the construction of [2]rotaxane and [2]pseudorotaxane architectures assisted by hydrogen bonding. The kinetic lability of the Pt(II)-N(pyridine) coordinative bond controls the dynamics of the [2]rotaxane. 相似文献
7.
1,1',3,3',6,6',8,8'-Octachloro-9,9'-bifluorenylidene and perchloro-9,9'-bifluorenylidene,two exceedingly twisted ethylenes 总被引:1,自引:0,他引:1
Molins E Miravitlles C Espinosa E Ballester M 《The Journal of organic chemistry》2002,67(21):7175-7178
The syntheses of 1,1',3,3',6,6',8,8'-octachloro-9,9'-bifluorenylidene (1), its precursors, and the byproduct 3,3',5,5'-tetrachloro-4-(trichloromethyl)biphenyl (5) are described. Accurate structural X-ray data on 1 and on perchloro-9,9'-bifluorenylidene (2) are reported and discussed. Because of chlorine overcrowding, the dihedral angles between their two identical fluorenylidene moieties are abnormally large, the central-ethylene twist angles being 55 and 66 degrees, respectively. Significant out-of-plane carbon-chlorine bond bending is likewise exhibited. Their ESR spectra and magnetic measurements prove that they are singlet species. The exceptionally large bathochromic displacements of their UV-vis absorption spectrum with respect to that of their parent hydrocarbon are mainly attributed to bond bending and molecular warping. 相似文献
8.
The oxidation of 2,3,5,6-tetrachloro--phenylenediamine with Cl2 or Br2 in CCl4 containing I2 affords unusual quinoniminium salts displaying remarkable chemical behaviour. 相似文献
9.
Oxidation of the perchlorotriphenylmethyl radical to the carbocation,and its unique abrupt reversion
Ballester M Miravitlles C Molins E Carreras C 《The Journal of organic chemistry》2003,68(7):2748-2751
A solution of AlCl(3) in CH(2)Cl(2) reacts slowly, at room temperature, with perchlorotriphenylmethyl radical (PTM(*)), an inert carbon free radical, to give perchlorotriphenylmethyl cation (PTM(+)) quantitatively. However, by gradual addition of CH(2)Cl(2) into the resulting solution a point is reached where the PTM(+) reverts to PTM(*) instantaneously and quantitatively. A mechanism for this exceptional phenomenon is suggested. Some PTM(+) reactions, namely hydrolysis yielding quinonoid species and single-electron transfers with hydride ion donors, are reported and discussed. 相似文献
10.
Fantuzzi G Pengo P Gomila R Ballester P Hunter CA Pasquato L Scrimin P 《Chemical communications (Cambridge, England)》2003,(8):1004-1005
N-Methylimidazole-functionalized gold nanoparticles behave as multivalent ligands for porphyrin arrays with an increase in binding strength of up to three order of magnitude with respect to a monovalent system. 相似文献