Fast, copper-free click chemistry: a convenient solid-phase approach to oligonucleotide conjugation

Solid-phase oligonucleotide conjugation by nitrile oxide-alkyne click cycloaddition chemistry has been successfully demonstrated; the reaction, compatible with all nucleobases, requires no metal catalyst and proceeds under physiological conditions.

Raman spectroelectrochemical studies and crystal structure of a binuclear copper(I) complex with a bridging diimine ligand

Raman spectroelectrochemical and X-ray crystallographic studies have been made for the binuclear copper(I) complex, [(Ph(3)P)(2)Cu(dpq)Cu(PPh(3))(2)][BF4](2), where dpq is the bridging ligand 2,3-di(2-pyridyl)quinoxaline. The X-ray data show that the pyridine rings are twisted out of plane with respect to the quinoxaline ring which is itself non-planar. The UV/VIS spectra of the metal-to-ligand charge-transfer excited state and those of the electrochemically reduced complex are similar. The resonance-Raman spectrum of the latter species exhibits little change in the frequency of the pyridinylquinoxaline inter-ring C-C bond stretching mode, compared to the ground electronic state. This suggests minimum change in the inter-ring C-C bond order in the electrochemically or charge-transfer generated radical anion. Semiempirical molecular-orbital calculations on both the neutral dpq and radical anion show two near-degenerate lowest unoccupied orbitals in the neutral species. One is strongly bonding across the inter-ring C-C bond while the other is almost nun-bonding. The Raman data suggest that it is this latter orbital which is populated in the transient and electrochemical experiments.

Transformation of vaterite into calcite in the absence and the presence of copper(II) species. Thermal analysis, IR and EPR study

The transformation of vaterite into calcite may be performed by heating in the presence and the absence of oxygen. Vaterite remains thermally stable until a calcination temperature of 450°C. It transforms progressively to calcite up to 500°C giving two exothermic peaks: 1) at 481°C due to the transformation of vaterite surface which is in contact with a small amount of calcite phase already formed with the time on the solid surface from the humidity atmosphere; 2) at 491°C due to the transformation of pure vaterite bulk. The calcite phase remains stable until 700°C. Above this temperature the formation of CaO is observed.

A simple method for assessing copper-mediated oxidation of very-low-density lipoprotein isolated by rapid ultracentrifugation

The association of very-low-density lipoprotein (VLDL) with atherosclerosis remains controversial. However, studies have shown that oxidative modification of VLDL can promote foam cell formation, leading to the development of atherosclerosis. A rapid method is described which will allow the significance of VLDL oxidation to be assessed in clinical studies. VLDL was isolated from heparinized plasma by a 1-h, single spin ultracentrifugation. Total protein was standardized to 25 mg/L. Oxidation was promoted by the addition of copper ions (17.5 mu mol/L, final concentration) incubated at 37 degrees C. Conjugated diene production was followed at 234 nm. Total assay preparation time was 2 h. Urate greatly inhibited the oxidation of VLDL and was successfully removed by size exclusion chromatography. VLDL isolated from frozen plasma (-70 degrees C) was stable for 15 weeks. This simple, rapid method for the isolation of VLDL may be applied to assess the significance of VLDL oxidation in disease.

Facile in situ synthesis of nanofluids based on ionic liquids and copper oxide clusters and nanoparticles

Two stable nanofluids comprising of mixed valent copper(_I,_II) oxide clusters (<1 nm) suspended in 1-butyl-3-methylimidazolium acetate, [C(₄)mim][OAc], and copper(_II) oxide nanoparticles (<50 nm) suspended in trioctyl(dodecyl) phosphonium acetate, [P-₈₈₈₁₂][OAc], were synthesised in a facile one-pot reaction from solutions of copper(_II) acetate hydrate in the corresponding ionic liquids. Formation of the nanostructures was studied using ¹³C NMR spectroscopy and differential scanning calorimetry (DSC). From a solution of Cu(OAc)₂ in 1-ethyl-3-methylimidazolium acetate, [C₂mim][OAc], crystals were obtained that revealed the structure of [C₂mim][Cu₃(OAc)₅(OH)₂(H₂O)]center dot H₂O, indicating the formation of copper hydroxo-clusters in the course of the reaction. Synthesised nanostructures were studied using transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Physical properties of the prepared IL-nanofluids were examined using IR and UV-VIS spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and densitometry.