Expanding the tools available for direct ortho cupration--targeting lithium phosphidocuprates

Reaction of in situ generated lithium phosphides with 0.5 eq. Cu(I) is employed as a means of targeting lithium phosphidocuprates of either Gilman- or Lipshutz-type formulation--e.g., (R(2)P)(2)CuLi·n(LiX) (n = 0, 1). For R = Ph, X = CN in toluene followed by thf or R = Ph, X = I in thf/toluene an unexpected product results. [(Ph(2)P)(6)Cu(4)][Li·4thf](2)1 reveals an ion-separated structure in the solid state, with solvated lithium cations countering the charge on an adamantyl dianion [(Ph(2)P)(6)Cu(4)](2-). Deployment of R = Ph, X = CN in thf affords a novel network based on the dimer of Ph(2)PCu(CN)Li·2thf 2 with trianions based on 6-membered (PCu)(3) rings acting as nodes in the supramolecular array and solvated alkali metal counter-ions completing the linkers. Cy(2)PLi (Cy = cyclohexyl) has been reacted with CuCN in thf/toluene to yield Gilman-type lithium bis(phosphido)cuprate (Cy(2)P)(2)CuLi·2thf 3 by the exclusion of in situ generated LiCN. A polymer is noted in the solid state.     

Investigations into beam monitors at the AEg ̄ IS experiment

Detailed diagnostic of antiproton beams at low energies is required for essentially all experiments at the Antiproton Decelerator (AD), but will be particularly important for the future Extra Low ENergy Antiproton ring (ELENA) and its keV beam lines to the different experiments. Many monitors have been successfully developed and operated at the AD, but in particular beam profile monitoring remains a challenge. A dedicated beam instrumentation and detector test stand has recently been setup at the AE \(\bar {g}\) IS experiment (Antimatter Experiment: Gravity, Interferometry, Spectroscopy). Located behind the actual experiment, it allows for parasitic use of the antiproton beam at different energies for testing and calibration. With the aim to explore and validate different candidate technologies for future low energy beam lines, as well as the downstream antihydrogen detector in AE \(\bar {g}\) IS, measurements have been carried out using Silicon strip and pixel detectors, a purpose-built secondary emission monitor and emulsions. Here, results from measurements and characterization of the different detector types with regard to their future use at the AD complex are presented.     

Systematic Control of Size and Morphology in the Synthesis of Gold Nanoparticles

The synthesis of gold nanoparticles (Au NPs) capped by poly(1‐vinylpyrrolidin‐2‐one (PVP, average  = 10 000 kDa) yields moderately dispersed (6–8.5 nm) product with limited morphological control while larger NPs (15–20 nm) are reliably prepared using trisodium citrate (Na₃Cit) as a reductant/capping agent. Excellent size control in the intermediate 10 nm regime is achieved by hybridizing these methodologies, with highly monodisperse, polycrystalline Au NPs forming. For a Na₃Cit:PVP:Au ratio of 3.5:3.5:1, anisotropic NPs with an aspect ratio of 1.8:1 suggest the systematic agglomeration of NP pairs. Enhanced control of NP morphology is allowed by the 1,2‐tetradecanediol reduction of Au^III in the presence of straight chain, molecular anti‐agglomerants. Last, ligand substitution is used to controllably grow preformed Au seeds. In spite of the extended growth phase used, the replacement of phosphine by 1‐pentadecylamine affords highly monodisperse, cuboidal NPs containing a single clearly visible twinning plane. The allowance of particle growth parallel to this close‐packed plane explains the remarkable particle morphology.     

Synthesis and calorimetric curing study of amino-terminated PEEK oligomers

Amino-terminated polyetheretherketone (PEEK) oligomers were prepared by the condensation of 4,4′-difluorobenzophenone and hydroquinone in the presence of a calculated excess of m-aminophenol endblocker. The molecular weight of the oligomer was controlled by the manipulation of the ratio of difluoride to hydroquinone with the appropriate stoichiometric amount of m-aminophenol ensuring amino termination. The thermally induced self-crosslinking of these oligomers was studied by differential scanning calorimetry (DSC). Curing was found to be quite slow, taking up to 1 h to reach completion at 668 K. Cured materials were all completely amorphous in contrast to the semi-crystalline starting material. The limiting T_g reached on curing was found to be proportional to the percentage of reactive terminal groups, as would be expected.     

Low-energy neon-ion scattering and neutralization on first and second layers of a Ni(001) surface

The scattering and neutralization of 2.4 and 5 keV Ne⁺ ions on the Ni(001) surface have been studied by time-of-flight (TOF) and electrostatic analyzer (ESA) techniques. The scattering yield of neutrals plus ions (by TOF) is strongly dependent on crystal orientation, in one direction being reduced by the shadowing of 2nd layer atoms by 1st layer atoms, or in another being increased by focussing of ions onto the 2nd layer by 1st layer atoms. Ion yields (by ESA) show little of this variation since the ions are largely neutralized on scattering from the second layer. The results thus demonstrate and explain the first layer selectivity of low-energy ion scattering by ESA for a case in which there is no shadowing of second layer atoms by the first layer. On the other hand, the ability to measure and distinguish first and second layer scattering of neutrals and ions by TOF suggests the possibility of composition analysis of individual layers of single crystal alloys and compound semiconductors.     

Charge states of 25–150 keV H and 4He backscattered from solid surfaces

Measurements have been made of the ion-fractions of H and ⁴He backscattered with energies of 25–160 keV from Cu, Au, and Si surfaces which were etched and washed but not atomically clean. The ion-fractions for H range from 0.37 at 25keV to 0.92 at 160 keV, and for ⁴He from 0.10 at 30keV to 0.58 at 150 keV, depending to a small extent on the target material. Where comparisons can be made the data agree rather closely with results of others for particles traversing thin foils. The data are useful for calibration of an electrostatic analyzer in surface analysis. Plots of ion-fraction against particle velocity show a primary dependence on velocity, as expected, but there is a small difference in slope between the H and He curves. Charge states of particles scattered from surface impurities did not deviate significantly from those of particles scattered from the substrate at the same energy.     

Electronic spectroscopy of the deuterated isotopomers of the NO.methane molecular complex

The molecular complexes formed between a nitric oxide molecule and the various deuterated isotopomers of the methane molecule have been studied in a supersonic jet expansion. The electronic spectrum arising from the transition corresponding to a 3s<--pi* excitation (approximately A (2)Sigma(+)<-- approximately X (2)Pi) located on the NO chromophore has been recorded employing resonance-enhanced multiphoton ionization spectroscopy, with each of CH(4), CH(3)D, CH(2)D(2), CHD(3), and CD(4) as the complexing partner. Rich spectra are obtained, whose appearance changes in a systematic way as the amount of deuteration increases. Unexpectedly, it was possible to record spectra not only in the parent mass channel, but also in various fragment channels; this also led to the identification of some O atom resonances; and their origin is discussed. Discussion is presented of the structure in the spectra, and its possible sources including hindered internal rotation of the methane and NO moieties, overall rotation of the complex, and tunneling. In addition, some guidance has been gleaned from ab initio calculations, and these are discussed in the light of the experimental results.     

Mechanochemical Activation of Zinc and Application to Negishi Cross‐Coupling

A form independent activation of zinc, concomitant generation of organozinc species and engagement in a Negishi cross‐coupling reaction via mechanochemical methods is reported. The reported method exhibits a broad substrate scope for both C(sp³)–C(sp²) and C(sp²)–C(sp²) couplings and is tolerant to many important functional groups. The method may offer broad reaching opportunities for the in situ generation organometallic compounds from base metals and their concomitant engagement in synthetic reactions via mechanochemical methods.     

Hydroxamate-based iron chelators: combinatorial syntheses of desferrioxamine B analogues and evaluation of binding affinities

This article describes the solid-phase combinatorial methods developed for the synthesis of polyhydroxamate-based siderophores. This strategy was applied to generate several libraries of structural DFO (1a) analogues that include DFO variants, non-amide analogues, C-terminal modified analogues, reverse-amide analogues, and hybrid analogues. To assess the relative iron-binding affinities of these compounds, a high-throughput spectrophotometric screening method based on competition with 8-hydroxyquinoline-5-sulfonic acid was developed. Some of the promising candidates containing various terminal functional groups were identified and prepared on large scale to enable future studies in animal models for iron-overload diseases.