Alkylation of ethyl bromomalonate by alkylcobaloximes

Allylcobaloximes react under very mild conditions with ethyl bromomalonate to yield allyl-substituted ethylmalonates in good yield. In the case of crotyl-, 3,3 dimethyl, allyl- and cinnamyl-cobaloximes, the substitution occurs with total rearrangement of the allyl groups. Similar rearrangements are observed during the reactions of propargyl- and allenylcobaloximes with BrCH(CO₂Et)₂ yielding allenyl- and propargyl-malonic esters respectively.     

ETAAS determination of aluminium and copper in dialysis concentrates after microcolumn chelating ion-exchange preconcentration

A procedure was developed for the preconcentration and determination of aluminium and copper in dialysis concentrates at the ng cm^–3 level. The preconcentration was achieved on microcolumns filled with Chelex-100 resin adjusted to a pH of 4.0. Five repetitive cycles of the sample through the column ensured a sufficient contact time for quantitative retention of aluminium and copper ions. The retained ions were eluted with HNO₃ (0.5 mol dm^–3). Aluminium and copper were determined in the eluate by Zeeman ETAAS using the standard addition technique. The procedure was performed under clean room conditions (class 10,000), The reliability of the results was evaluated by recovery tests, using dialysis concentrates spiked with aluminium and copper. The recoveries obtained ranged from 86 to 106% for aluminium and from 92 to 97% for copper. Using the recommended procedure, the LOD of aluminium and copper in dialysis concentrates (preconcentration factor 2) was found to be 0.5 ng cm^–3 and 0.2 ng cm^–3, respectively. Received: 19 December 1997 / Revised: 10 March 1998 / Accepted: 28 March 1998     

EPR Study of Ligand Effects in Spin Triads of Bis(o-Semiquinonato)Copper(II) Complexes

We report the X-band (9 GHz) electron paramagnetic resonance (EPR) study of series of bis(o-semiquinonato)copper(II) complexes with different ligands. It was found previously, that exchange interactions in spin triads of these compounds are very sensitive to the structure of the ligand coordinated to the central copper(II) ion. Ligand moderates the copper–radical and radical–radical exchange interactions and strongly changes the magnetic properties of the compound. Depending on a ligand, ferromagnetic or antiferromagnetic character of exchange dominates in the system. The EPR study of these complexes allowed us to obtain information on zero-field splitting parameters and their distributions in the studied compounds. The EPR results compliment previously obtained spectroscopic data on these compounds and suggest the pronounced plasticity of the clusters manifested in the broad distributions of their rhombicity parameters.     

Investigation of the solubilization of car-emitted Pt,Pd and Rh in street dust and spiked soil samples

A sequential extraction procedure (three-step), proposed by the Standards, Measurements and Testing Programme (formerly BCR) of the European Union, was applied to street dust and spiked soil samples for the determination of PGEs. Analyses were carried out using inductively coupled plasma-mass spectrometry (ICP-MS). The results indicate that up to 5% from Pt, 70% from Pd and 14% from Rh are in mobile forms in street dust. The results for the soil samples spiked with crushed catalytic converter are significantly lower indicating that PGEs are oxidised more efficiently in natural conditions. Additionally Pt and Pd bound to humic acids were investigated.     

IR Microscopy as a Method for Studying the Influence of An External Electric Field on the Spin Crossover Exemplified by the Fe(II) Complex with 2,6-Bis(pyrazol-1-yl)pyridine

Russian Journal of Coordination Chemistry - The influence of the electric field on the spin state of the single crystal of [Fe(1-Bpp)2][BF4]2 demonstrating the spin crossover phenomenon is studied....     

Laser vibrometry based on analysis of the speckle pattern from a remote object

A novel technique is represented that allows one to measure vibrations from a distant object with micron and sub-micron amplitudes in real time.     

Synthesis and mesomorphic properties of some aryl β-D-C-glycosides

The synthesis of some aryl β-D-C-glycosides bearing long alkoxy chains (grafted on the carbohydrate moiety through the intermediate of an aromatic core) is described. Their mesomorphic properties (studied by microscopic observations under polarized light, DSC and X-ray diffraction) are presented.     

Selective adsorption of proteins on single-wall carbon nanotubes by using a protective surfactant

The dispersion of highly hydrophobic carbon materials such as carbon nanotubes in biological media is a challenging issue. Indeed, the nonspecific adsorption of proteins occurs readily when the nanotubes are introduced in biological media; therefore, a methodology to control adsorption is in high demand. To address this issue, we developed a bifunctional linker derived from pyrene that selectively enables or prevents the adsorption of proteins on single-wall carbon nanotubes (SWNTs). We demonstrated that it is possible to decrease or completely suppress the adsorption of proteins on the nanotube sidewall by using proper functionalization (either covalent or noncovalent). By subsequently activating the functional groups on the nanotube derivatives, protein adsorption can be recovered and, therefore, controlled. Our approach is simple, straightforward, and potentially suitable for other biomolecules that contain thio or amino groups available for coupling.