Adsorption of oligooxypropylenated amines at the aqueous solution—air interface: Homologous series of piperidine and morpholine derivatives

The surface tension isotherms for pure oligooxypropylenated piperidine and morpholine at the aqueous solution—air interface were determined and interpreted. The surface excess concentration, Γ, the surface area per molecule, A, and the standard free energy of adsorption, ΔG°, were calculated according to a new empirical adsorption equation. The standard free energy contribution for the oxypropylene group (PO) in morpholine derivatives,ΔG° (PO) = −3.34 kJ mol⁻¹, is substantially lower than that for the PO group located in the piperidine derivatives, i.e. ΔG° (PO)= −3.12 kJ mol⁻¹.     

Synthesis of some heterocyclic skeletons via organoiron complexes. Crystal and molecular structure of (5a,6,7,8,9,9a-η6-1,4-benzoxathiino[3,2-b]pyridine)(η5-cyclopentadienyl)iron hexafluorophosphate

Synthesis of the heterocyclic skeletons of some biologically active compounds from (η⁶-o-dichlorobenzene)(η⁵-cyclopentadienyrl)iron hexafluorophosphate in a two step procedure is described. Cyclopentadienyliron hexafluorophosphate complexes of 1,4-benzodioxino[2,3-b]pyridine, 1,4-benzoxathiino[3,2-b]pyridine, 10H-pyrido[3,2-b]benzoxazine, benzo[b]naphtho[2,3-e][1,4]dioxin, 4-methylbenzo[b]benzopyran-2-one[7,6-e][1,4]dioxin and benzo[b]anthracen-9,10-diono[1,2-e][1,4]dioxin were isolated and characterized. Upon pyrolytic sublimation of these complexes the free heterocycles were obtained and characterized. (η⁶-1,4-Benzoxathiino[3,2-b]pyridine)(η⁵-cyclopentadienyl)iron hexafluorophosphate crystalizes in the orthothombic system, space group Pbca; the dihedral angle between the planes of outer rings was found to be 176.8 (1).     

Comparative study of capillary electroendosmotic chromatography and electrically assisted gradient nano-liquid chromatography for the separation of peptides

Capillary electroendoendosmotic chromatography (CEC), being a hybrid of high-performance liquid chromatography (HPLC) and capillary electrophoresis, offers considerable changes to enhance column efficiency, speed of analysis and additional selectivity as compared to the parent methods. The analytes are driven by the electroendosmotic flow (EOF) and separated by surface-solute interactions as well as by differences in electromigration. In this paper on the separation of peptides on C18 reversed-phase and mixed-mode (sulphonic acid-n-alkyl) packings in CEC and electrically assisted reversed-phase gradient nano-LC are investigated. It is shown that mixed mode packings generate a higher EOF than reversed-phase packings that is scarcely dependent on the pH of the eluent. Applying a potential in gradient elution reversed-phase nano-LC of peptides shortens the analysis time as compared to separations without a potential. Electrically assisted reversed-phase gradient elution nano-LC is a powerful separation tool for analysis of tryptic digests. Peptides can be successfully resolved in acidic organic mobile phase at pH 2-3 with and without trifluoroacid as ion pairing reagent under isocratic conditions. It is demonstrated that CEC with mixed mode packing and an eluent of pH 2.3 with varying acetonitrile content can be applied to monitor impurities in a synthetic peptide.     

Water addition to a two-electron mixed-valence bimetallic center

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.     

A highly chemoselective oxidation of alcohols to carbonyl products with iodosobenzene diacetate mediated by chromium(III)(salen) complexes: synthetic and mechanistic aspects

[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)()).     

Direct episulfidation of alkenes and allenes with elemental sulfur and thiiranes as sulfur sources,catalyzed by molybdenum oxo complexes

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.     

Phosphorus hyperfine structure in the electronic spectrum of the HPCl free radical

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.     

Analytical techniques for cyanide in blood and published blood cyanide concentrations from healthy subjects and fire victims

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.     

Pinkment: a synthetic platform for the development of fluorescent probes for diagnostic and theranostic applications

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.     

First experiments on transmutation studies of129I and237Np using relativistic protons of 3.7 GeV

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.