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51.
The synthesis and characterization of cationic platinum complexes of the type [(R(2)PC(2)H(4)PR(2))PtMe(OEt(2))]BAr(F) (R = Cy, Et) are reported. These electrophilic platinum cations are found to react quantitatively with arenes (benzene, toluene) at room temperature by undergoing intermolecular C-H activation with concomitant C-C coupling to generate complexes of the type [[Pt(R(2)PC(2)H(4)PR(2))](2)(mu-eta(3):eta(3)-biaryl)][BAr(F)](2). The dianionic biaryl ligands in these compounds exhibit a rare mu-eta(3):eta(3)-bis-allyl bonding mode and can be removed from the complex with stoichiometric oxidants to generate the free biaryl and [(R(2)PC(2)H(4)PR(2))Pt(mu-X)](2)[BAr(F)](2) (R = Cy, Et; X = Cl, I). The cationic platinum complexes [(R(2)PC(2)H(4)PR(2))PtMe(OEt(2))]BAr(F) (R = Cy, Et) are also quite reactive with water, forming the bridging hydroxide complexes [(R(2)PC(2)H(4)PR(2))Pt(mu-OH)](2)[BAr(F)](2) (R = Cy, Et). A possible mechanism is proposed for the C-C coupling reaction based upon the structures of these bridging biphenyl complexes, which provides a new perspective for the related palladium-catalyzed oxidative coupling of arenes to form biaryls. 相似文献
52.
Ning Luo J. Brian Hutchison Kristi S. Anseth Christopher N. Bowman 《Journal of polymer science. Part A, Polymer chemistry》2002,40(11):1885-1891
(Methacryloyl ethylenedioxycarbonyl) benzyl N,N‐diethyldithiocarbamate (HEMA‐E‐In) was synthesized and used as a monomer iniferter to develop a novel, photopatternable grafting technology. This molecule functions as both a methacrylic monomer and a photoiniferter (photoinitiator–transfer agent–terminator). The structure of HEMA‐E‐In was characterized by 1H NMR, Fourier transform infrared, and ultraviolet–visible spectroscopies. In the presence of the monomer iniferter, methyl methacrylate was polymerized by exposure to 365‐nm ultraviolet radiation, confirming the initiation capability of HEMA‐E‐In. After the copolymerization of HEMA‐E‐In into a methacrylate‐based polymer, attenuated total reflectance Fourier transform infrared spectra revealed that the photoiniferter functionality was present at the surface of this polymeric substrate. Photografting of poly(ethylene glycol) monomethacrylate monomer from the surface caused a significant change in the hydrophobicity of the surface as demonstrated by contact angle measurements. The novel monomer photoiniferter HEMA‐E‐In initiates the polymerization of bulk monomer and provides a reactive functionality that facilitates further initiation and polymer modification by the polymerization of different monomers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1885–1891, 2002 相似文献
53.
Abstract— A labile intermediate in the photolytic rearrangement of the antibacterial drug, metronidazole, was identified by isolating the product of photolysis of metronidazole benzoate in methanol. The intermediate, 1-hydroxyethyl-2-methyl-4-hydroxyimino-5-oxo-imidazole, was shown to act as a bidentate chelating agent for copper(II) ions, whereas metronidazole forms a weak monodentate complex. The intermediate may be relevant to the bioactivation mechanism of metronidazole. 相似文献
54.
55.
Summary A procedure for SIMS semiquantitative analysis, based on the use of one fitting-parameter, has been applied to metal and mineral standards with satisfactory results. Values of this parameter for various matrices are given, and prospects for analyses involving no reference elements are discussed. Analytical accuracies obtainable for individual elements are assessed in terms of matrix-independent error factors.
Presented at the International Symposium on Microchemical Techniques 1977, Davos, May 1977. 相似文献
Zusammenfassung Eine Methode zur semiquantitativen SIMS-Analyse, die im Gegensatz zu den aus der Literatur bekannten Verfahren nur einen Anpassungsparameter benötigt, wurde mit gutem Erfolg an Metall- und Mineralstandards getestet. Werte des Anpassungsparameters für verschiedene Matrices wurden angegeben und Aussichten für eine Weiterentwicklung dieser Methode in Richtung auf standardfreie Analysen wurden besprochen. Die analytische Richtigkeit für einige Elemente wurde mit Hilfe von matrixunabhängigen Fehlerfaktoren abgeschätzt.
Presented at the International Symposium on Microchemical Techniques 1977, Davos, May 1977. 相似文献
56.
Dendritic molecular capsules for hydrophobic compounds 总被引:1,自引:0,他引:1
Morgan MT Carnahan MA Immoos CE Ribeiro AA Finkelstein S Lee SJ Grinstaff MW 《Journal of the American Chemical Society》2003,125(50):15485-15489
Reichardt's dye, a highly solvatochromic dye, was encapsulated within poly (glycerol succinic acid) ([Gn]-PGLSA-OH) dendrimers to investigate the interior environment of these dendritic macromolecules. The absorption maximum for the encapsulated Reichardt's dye in water was indicative of a relatively high dielectric constant present within the dye/dendrimer complex. (1)H NMR of the encapsulated complex showed the presence of aromatic protons from Reichardt's dye along with the aliphatic protons of the dendrimer. Additionally, there were substantial changes in T(1) and T(2) times of the encapsulated dye when compared with the free dye, and (1)H NOESY spectra for the complex showed a significant number of intermolecular NOE cross-peaks. These data reveal the close through-space proximity of the dye to the dendrimer and the restricted motion of the encapsulated dye. To demonstrate the potential use of these macromolecules as drug delivery vehicles, the poorly water-soluble anticancer drug 10-hydroxycamptothecin (10HCPT) was encapsulated within a carboxylated PGLSA dendrimer ([G4]-PGLSA-COONa). Cytotoxicity assays with human breast cancer cells showed a significant reduction of cell viability, demonstrating that 10HCPT retains activity upon encapsulation. 相似文献
57.
58.
Brian F.G. Johnson Jack Lewis Martyn V. Twigg 《Journal of organometallic chemistry》1974,67(3):C75-C76
Photolysis of Ru3(CO)12 in the presence of donor ligands rapidly produces monomeric ruthenium species. 相似文献
59.
60.
Summary The chromatographic performance of newly developed dicyanobiphenyl polysiloxane stationary phases were evaluated and compared
with the performance of other polar stationary phases, including the previously reported monocyanobiphenyl polysiloxanes.
Due to the unique combination of polarizable biphenyl and polar cyano functionalities in the side chains of the flexible polysiloxane
backbone, and by virtue of their mild liquid crystalline properties, the new stationary phases provide excellent resolution
of a wide variety of analytes, both polar and nonpolar, in both GC and SFC. They can be easily coated and cross-linked in
open tubular columns, and the resultant columns demonstrate excellent efficiency and performance at temperatures up to 280–300°C.
The new stationary phases exhibit enhanced selectivities for various types of isomeric compounds. 相似文献