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581.
New Convenient Methods for the Preparation of Pendant Chain Cyclobutadiene Tricarbonyliron Complexes
Christopher M. Adams John E. Schemenaur Ellen S. Crawford Scott A. Joslin 《合成通讯》2013,43(10):1385-1396
Simple, economical, and more practical procedures have been developed for the synthesis of precursors to pendant chain cyclobutadiene metal complexes. Facile reduction of the mono and disubstituted 1,2-cyclobutenediones gave cyclobutenediols which were converted to their corresponding trans dibromides with PBr3. Reduction and complexation using Fe2(CO)9 formed the pendant chain cyclobutadiene tricarbonyliron complexes in good yields. 相似文献
582.
Ellen D. Inutan James Wager-Miller Srinivas B. Narayan Ken Mackie Sarah Trimpin 《International Journal for Ion Mobility Spectrometry》2013,16(2):145-159
Recently discovered ionization methods for use in mass spectrometry (MS), are widely applicable to biological materials, robust, and easy to automate. Among these, matrix assisted ionization vacuum (MAIV) is astonishing in that ionization of low and high-mass compounds are converted to gas-phase ions with charge states similar to electrospray ionization simply by exposing a matrix:analyte mixture to the vacuum of a mass spectrometer. Using the matrix compound, 3-nitrobenzonitrile, abundant ions are produced at room temperature without the need of high voltage or a laser. Here we discuss chemical analyses advances using MAIV combined with ion mobility spectrometry (IMS) real time separation, high resolution MS, and mass selected and non-mass selected MS/MS providing rapid analyte characterization. Drugs, their metabolites, lipids, peptides, and proteins can be ionized simultaneously from a variety of different biological matrixes such as urine, plasma, whole blood, and tissue. These complex mixtures are best characterized using a separation step, which is obtained nearly instantaneously with IMS, and together with direct ionization and MS or MS/MS provides a fast analysis method that has considerable potential for non-targeted clinical analyses. 相似文献
583.
Sourav Chakraborty Eric Schreiber Karla R. Sanchez-Lievanos Mehrin Tariq William W. Brennessel Kathryn E. Knowles Ellen M. Matson 《Chemical science》2021,12(38):12744
We report the synthesis and characterisation of a series of siloxide-functionalised polyoxovanadate–alkoxide (POV–alkoxide) clusters, [V6O6(OSiMe3)(OMe)12]n (n = 1−, 2−), that serve as molecular models for proton and hydrogen-atom uptake in vanadium dioxide, respectively. Installation of a siloxide moiety on the surface of the Lindqvist core was accomplished via addition of trimethylsilyl trifluoromethylsulfonate to the fully-oxygenated cluster [V6O7(OMe)12]2−. Characterisation of [V6O6(OSiMe3)(OMe)12]1− by X-ray photoelectron spectroscopy reveals that the incorporation of the siloxide group does not result in charge separation within the hexavanadate assembly, an observation that contrasts directly with the behavior of clusters bearing substitutional dopants. The reduced assembly, [V6O6(OSiMe3)(OMe)12]2−, provides an isoelectronic model for H-doped VO2, with a vanadium(iii) ion embedded within the cluster core. Notably, structural analysis of [V6O6(OSiMe3)(OMe)12]2− reveals bond perturbations at the siloxide-functionalised vanadium centre that resemble those invoked upon H-atom uptake in VO2 through ab initio calculations. Our results offer atomically precise insight into the local structural and electronic consequences of the installation of hydrogen-atom-like dopants in VO2, and challenge current perspectives of the operative mechanism of electron–proton co-doping in these materials.We report the synthesis and characterisation of a series of siloxide-functionalised polyoxovanadate–alkoxide clusters, [V6O6(OSiMe3)(OMe)12]n (n = 1−, 2−), that serve as molecular models for proton and hydrogen-atom uptake in vanadium dioxide. 相似文献
584.
In this contribution, the numerical modeling of electro-viscoelastic material is considered. The electro-mechanical problem formulated in terms of a symmetrized stress tensor is extended to a viscoelastic material model. For the incorporation of the viscosity model, the logarithmic strain space setting is utilized which mimics the small strain setting. Therefore a rheological model for viscosity from the geometrically linear theory can be used. Numerical examples for a typical uniaxial tensile test show the capability of the method to demonstrate typical relaxation and creep behavior. (© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
585.
Irene Lim Eric Yu Lin Joseph Garcia Shang Jia Robert E. Sommerhalter Subrata K. Ghosh John A. Gladysz Ellen M. Sletten 《Angewandte Chemie (International ed. in English)》2023,62(6):e202215200
Developing chemical tools to detect and influence biological processes is a cornerstone of chemical biology. Here we combine two tools which rely on orthogonality– perfluorocarbons and multiplexed shortwave infrared (SWIR) fluorescence imaging– to visualize nanoemulsions in real time in living mice. Drawing inspiration from fluorous and SWIR fluorophore development, we prepared two SWIR-emissive, fluorous-soluble chromenylium polymethine dyes. These are the most red-shifted fluorous fluorophores– “fluorofluorophores”—to date. After characterizing the dyes, their utility was demonstrated by tracking perfluorocarbon nanoemulsion biodistribution in vivo. Using an excitation-multiplexed approach to image two variables simultaneously, we gained insight into the importance of size and surfactant identity on biodistribution. 相似文献