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91.
Alvarez S Aullón G Fandos R García Fierro JL Ocón P Otero A Rojas S Terreros P 《Dalton transactions (Cambridge, England : 2003)》2005,(5):938-944
The reaction of [Rh(micro-Cl)(COD)]2 with 4,6-dimethyl-pyrimidinethiolate (Me2-pymt) and subsequent substitution of COD by CO yields [Rh(Me2-pymt)(CO)2]. The stacking pattern found in this compound is in contradiction with previously studied comparable square-planar complexes of type d8-[M(chelate)(monodentate)2] in which each ligand has different pi-acidic character. A theoretical study of the intermolecular interactions and conformation of the title compound has been carried out, combining semi-empirical band calculations on the real chains and ab initio(MP2 level) calculations on a model dimer. The combination of electronic and steric effects determines the rotation of the successive monomers and the deviation from linearity of the one-dimensional stacks. Its behaviour in solution is also special, developing a blue colour and forming micelles, when adding water to acetone solutions. 相似文献
92.
Domenico Armenise Nicolino De Laurentis Antonia Reho Antonio Rosato Flaviano Morlacchi 《Journal of heterocyclic chemistry》2004,41(5):771-775
A series of 6‐fluoro‐4‐(5 or 7)‐chloro‐2‐(difluorobenzoyl)aminobenzothiazoles 3a‐r were prepared to investigate their potential biological activity. In this work, the results of their in vitro antifungal activity against some strains of Candida albicans are reported. It was found that some derivatives displayed antifungal activity higher than that for 3k [1a] compound already described in literature. 相似文献
93.
Andrea Cornia Antonio Costantino Fabretti Roberta Sessoli Lorenzo Sorace Dante Gatteschi Anne‐Laure Barra Carole Daiguebonne Thierry Roisnel 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(7):m371-m373
The structure of hexadeca‐μ‐acetato‐tetraaquadodeca‐μ3‐oxo‐dodecamanganese bis(acetic acid) tetrahydrate, [Mn12O12(CH3COO)16(H2O)4]·2CH3COOH·4H2O, known as Mn12–acetate, has been determined at 83 (2) K by X‐ray diffraction methods. The fourfold (S4) molecular symmetry is disrupted by a strong hydrogen‐bonding interaction with the disordered acetic acid molecule of solvation, which displaces one of the acetate ligands in the cluster. Up to six Mn12 isomers are potentially present in the crystal lattice, which differ in the number and arrangement of hydrogen‐bonded acetic acid molecules. These results considerably improve the structural information available on this molecular nanomagnet, which was first synthesized and characterized by Lis [Acta Cryst. (1980), B 36 , 2042–2046]. 相似文献
94.
Atomic force microscopy imaging of hair: correlations between surface potential and wetting at the nanometer scale 总被引:2,自引:0,他引:2
Dupres V Camesano T Langevin D Checco A Guenoun P 《Journal of colloid and interface science》2004,269(2):329-335
We report investigations of hair surface potential under wetting at the nanometric scale by atomic force microscopy (AFM). Surface potential imaging was used to characterize the electrostatic properties of the hair samples. We found that the surface potential noticeably increases along the edges of the cuticles. These results are correlated with wetting behavior of different liquids performed using AFM in noncontact mode. 相似文献
95.
Antonio Currao Nantko Feiken Alceo Macchioni Reinhard Nesper Paul S. Pregosin Gerald Trabesinger 《Helvetica chimica acta》1996,79(6):1587-1591
The ligand (6,6′-dimethoxybiphenyl-2,2′-diyl)bis[3,5-di(tert-butyl)phenylphosphine] ( 1 ) forms an unexpectedly stable hydrido-bis-solvento complex of composition [RuH(isopropanol)2( 1 )]BF4, ( 2 ) under the conditions used in the enantioselective hydrogenation of pyrones. The structure of 2 , determined by X-ray diffraction, represents the first well-characterized chiral five-coordinate bis-phosphine ruthenium-hydride complex stable as a solvento complex, and provides a structural link in the enantioselective pyrone hydrogenation cycle catalyzed by [Ru(OAc)2( 1 )]. Using the arene complex [RuH(p-cymene)( 1 )]BF4 ( 3 ), the chiral pocket of coordinated 1 is shown to be relatively rigid, via NMR spectroscopy. This is reflected in restricted rotation about one of the four P–[3,5-di(tert-butyl)phenyl] P? Cipso bonds at room temperature. 相似文献
96.
José M. Sánchez-Montero JOSé V. Slnisterra Antonio Ballesteros 《Applied biochemistry and biotechnology》1989,22(2):205-214
The endonuclease from S. aureus has been immobilized on ground maize cob, previously activated with tosyl chloride. Pretreatment of the support on acid before tosylation yielded the best insoluble enzyme derivatives. The catalytic activity has been evaluated as percent of total hydrolysis attained in a batch reactor using DNA as a model substrate. The derivatives prepared are very resistant to high temperatures under conditions of catalysis (24 h at 45 degrees C). For these long reaction times, the extent of hydrolysis in the presence of small amounts of organic solvent (dimethyl sulfoxide at 2 percent) is larger than in plain buffer (Tris). This type of derivative could be very useful for the removal of nucleic acids from single-cell protein concentrates. 相似文献
97.
The technique of bead injection has been adapted for surface enhanced Raman scattering (SERS) to substantially improve precision, long term stability and sensitivity of SERS detection in analytical chemistry. For this purpose a fully automated flow system comprising a dedicated flow-cell has been developed and tested. With the developed flow-cell, which contains two inlet and two outlet channels, it is possible to retain, perfuse and discharge minute amounts of polymer beads while monitoring all steps by Raman spectroscopy. First, beads carrying cation exchanger moieties were retained in the flow-cell and subsequently perfused with a silver nitrate and a hydroxylamine solution using one inlet of the flow cell. By this sequence homogeneous SERS active silver layers were formed on the beads. The uniformity of the achieved silver layer was studied by secondary electron microscopy. For measurement, the analyte was then introduced from the second inlet channel such that the interaction between the activated SERS beads and analyte occurred in close proximity and within the focus of the laser excitation beam. Due to the complete computer control of all experimental steps, including bead entrapment, SERS layer generation, sample introduction and final bead removal, highly reproducible conditions for SERS were achieved. The method was developed using 9-aminoacridine as a test molecule. Quantitative studies were carried out for 9-aminoacridine and acridine showing linear calibrations from 1-100 nmol l(-1) and 50-1,000 nmol l(-1), respectively, using a sample volume of 200 microl each. Typical relative standard deviations were 4.7% for 9-aminoacrine and 5.8% for acridine. 相似文献
98.
Regás D Afonso MM Rodríguez ML Palenzuela JA 《The Journal of organic chemistry》2003,68(20):7845-7852
The reaction of vinyl allenes with imines under Lewis acid catalysis has been explored. Vinyl allenes in which the allenic portion of the molecule is tri- or tetrasubstituted gave octahydroquinoline derivatives as single isomers together with a minor compound formed by an ene reaction of the imine with the allene. Compounds in which the allene is 1,3-disubstituted do not react under the conditions assayed. 相似文献
99.
We study the dynamics in the neighborhood of an invariant torus of a nearly integrable system. We provide an upper bound to the diffusion speed, which turns out to be of superexponentially small size exp[-exp(1/)], being the distance from the invariant torus. We also discuss the connection of this result with the existence of many invariant tori close to the considered one. 相似文献
100.
Antonio Cipiciani Stefania Primieri Antonio Arcelli 《Journal of inclusion phenomena and macrocyclic chemistry》1994,15(3):207-214
The hydrolysis reaction of 2-nitro-4-carboxyphenyl acetate was studied in dichloromethane in the presence of an added electrolyte (NaOH) and cationic surfactants systems with varying quantities of added water at 25°C. The kinetic and conductivity data were correlated. 相似文献