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101.
Water adds to the two-electron mixed-valence Ir(0,II)(2) core of Ir(2)(tfepma)(3)Cl(2)(tfepma = MeN[P(OCH(2)CF(3))(2)](2)) to cleanly generate an Ir(I,III)(2) hydride. Dehydrohalogenation across the Ir-Ir bond returns the complex to an Ir(0,II)(2) species. 相似文献
102.
[reaction: see text] The catalytic oxidation of the allylic alcohols 1d-n with iodosobenzene diacetate, mediated by the [Cr(III)(salen)]X complex, affords the respective enones in excellent chemoselectivity for Cl(-) as counterion [complex A(Cl)], while for the counterions TfO(-) [complex A(TfO)] and PF(6)(-) [complex A(PF(6)())] nearly equal amounts of enone and epoxide are observed. This counterion-dependent oxidation of allylic alcohols by Cr(III)(salen) complexes is rationalized in terms of Lewis acid catalysis by the complex A(Cl) and redox catalysis for A(TfO) and A(PF(6)()). 相似文献
103.
The molybdenum oxo complexes 1a and 1b catalyze efficiently the sulfur transfer to a series of alkenes 4 and allenes 6, for which elemental sulfur, phenylthiirane, or methylthiirane have been employed as sulfur sources to afford the corresponding episulfides 5 and 7. The most effective catalytic episulfidation system to date is the combination of the dithiophosphate-ligated oxo complex 1b and phenylthiirane (Ibeta). This metathesis process is efficient enough to convert usually reluctant alkenes (cyclopentene, cycloheptene, Z-cyclooctene, Z-cyclononene, E-cyclodecene, norbornene, and even bicyclopropylidene) to their episulfides in good yields under mild conditions. The direct catalytic sulfuration of allenes (cyclonona-1,2-diene, cyclonona-1,2,5-triene, cyclodeca-1,2-diene, and 2,4-dimethylpenta-2,3-diene) to their labile methylenethiiranes is unprecedented. 相似文献
104.
The 444 nm 2 0 (1) bands of the A 2A'-X 2A" transition of the jet-cooled HP 35Cl and HP 37Cl radicals have been studied at high resolution using the pulsed electric discharge technique with a precursor mixture of PCl3 and H2. Spectra recorded with linewidths of approximately 360 MHz revealed resolved hyperfine structure in both isotopomers arising from the excited state Fermi contact interaction of the unpaired electron with the magnetic moment of the 31P nucleus, with aF'=0.0641(10) cm(-1) and 0.0636(31) cm(-1) for HP 35Cl and HP 37Cl, respectively. No contribution from the ground state, or excited state contributions from the hydrogen or chlorine nuclei were resolved, confirming ab initio predictions that HPCl is a p pi radical in the X state, and an s sigma radical with a substantial contribution from the phosphorus 3s atomic orbital in the A state. The free atom comparison method has been used to estimate that the singly occupied molecular orbital in the excited state has 14% phosphorus 3s character. 相似文献
105.
Hydrogen cyanide can be produced by the pyrolysis of man-made polymers. Cyanide has been measured in the blood of healthy adults as well as the blood of fire survivors and fatalities. In healthy subjects the blood cyanide concentration of smokers is higher than that of non-smokers. Fire survivors and fatalities have been found to have higher cyanide levels than of control groups and the levels from fire fatalities are often higher than survivors. Blood concentrations quoted as normal, toxic or fatal are highly variable in the literature. Many studies have been performed to measure the blood cyanide levels in control subjects as well as those who have been exposed to fire but the values found differ. The values for control subjects can vary from none detected to 19 μmol dm−3 while those for fire survivors range from not detected to 150 μmol dm−3 and fatalities range from not detected to 284 μmol dm−3. Analytical techniques and published data are critically reviewed.Many of the existing antidotes for cyanide poisoning are highly toxic themselves and should ideally be administered at doses proportional to the amount of cyanide a patient has received to avoid compounding damage done by cyanide intoxication. For this reason, a rapid, accurate bedside assay of blood cyanide concentration that differentiates between bound and free cyanide would represent a leap forward in the clinical management of cyanide poisoning. 相似文献
106.
Maria Weber Hai-Hao Han Bo-Han Li Maria
L. Odyniec Charlotte E. F. Jarman Yi Zang Steven D. Bull Amanda B. Mackenzie Adam C. Sedgwick Jia Li Xiao-Peng He Tony D. James 《Chemical science》2020,11(32):8567
Reaction-based fluorescent-probes have proven successful for the visualisation of biological species in various cellular processes. Unfortunately, in order to tailor the design of a fluorescent probe to a specific application (i.e. organelle targeting, material and theranostic applications) often requires extensive synthetic efforts and the synthetic screening of a range of fluorophores to match the required synthetic needs. In this work, we have identified Pinkment-OH as a unique “plug-and-play” synthetic platform that can be used to develop a range of ONOO− responsive fluorescent probes for a variety of applications. These include theranostic-based applications and potential material-based/bioconjugation applications. The as prepared probes displayed an excellent sensitivity and selectivity for ONOO− over other ROS. In vitro studies using HeLa cells and RAW 264.7 macrophages demonstrated their ability to detect exogenously and endogenously produced ONOO−. Evaluation in an LPS-induced inflammation mouse model illustrated the ability to monitor ONOO− production in acute inflammation. Lastly, theranostic-based probes enabled the simultaneous evaluation of indomethacin-based therapeutic effects combined with the visualisation of an inflammation biomarker in RAW 264.7 cells. Pinkment, a resorufin based ONOO− selective and sensitive ‘plug and play’ fluorescence-based platform for in vitro and in vivo use, enables facile functionalisation for various imaging and theranostic applications. 相似文献
107.
M. I. Krivopustov J. Adam V. Bradnova R. Brandt V. S. Butsev P. I. Golubev V. G. Kalinnikov J. Karachuk B. A. Kulakov E.-J. Langrock G. Modolo M. Ochs R. Odoj A. N. Premyshev V. S. Pronskich Th. Schmidt V. I. Stegailov J. S. Wan V. M. Zupko-Sitnikov 《Journal of Radioanalytical and Nuclear Chemistry》1997,222(1-2):267-270
First experiments on the transmutation of long-lived129I and237Np using relativistic protons of 3.7 GeV are described. Relativistic protons generate in extended Pb-targets substancial neutron fluences. These neutrons get moderated in paraffin and are used for transmutation as follows:129I(n,)130I and237Np(n,)238Np. The isotopes130I (T
1/2-12.36 h) and238Np (T
1/2=2.117 d) were identified radiochemically. One can estimate the transmutation cross-section (n,) in the given neutron field as (129I(n,))=(10±2)b and (237Np(n,))=(140±30)b The experiments were carried out in November 1996 at the Synchrophasotron, LHE, Dubna, Russia. The investigation has been performed at the Laboratory of High Energies, JINR, Dubna. 相似文献
108.
[structure: see text] Chitin synthase (CS) polymerizes UDP-GlcNAc to form chitin (poly-beta(1,4)-GlcNAc), a key component of fungal cell wall biosynthesis. Little is known about the substrate specificity of chitin synthase or the scope of substrate modification the enzyme will tolerate. Following a previous report suggesting that 6-O-dansyl GlcNAc is biosynthetically incorporated into chitin, we became interested in developing an assay for CS activity based on incorporation of a fluorescent substrate. We describe the synthesis of two fluorescent UDP-GlcNAc analogues and their evaluation as chitin synthase substrates. 相似文献
109.
Maciejewska Gabriela Cieślak-Golonka Maria Staszak Zbigniew Szeląg Adam 《Transition Metal Chemistry》2002,27(6):587-593
Six new heteropolynuclear chromium(III)/vanadium(V) complexes with natural ligands: glycine, glutaminic, nicotinic and asparginic acids, have been isolated and physicochemically characterised. The complexes have been analysed using spectroscopic (diffuse reflectance u.v.–vis., i.r.), magnetic methods and by FAB mass spectra. Spectral analyses with the digital filter and band deconvolution methods are presented. Additionally, preliminary toxicity studies have been performed. 相似文献
110.
A series of β,γ‐unsaturated ketones were isomerized to their corresponding α,β‐unsaturated ketones by the introduction of DABCO in iPrOH at room temperature. The endo‐cyclic double bond (β,γ‐position) on ketone was rearranged to exo‐cyclic double bond (α,β‐position) under the reaction conditions. 相似文献