High-efficiency hydrophilic interaction chromatography by coupling 25 cm × 4.6 mm ID × 5 μm silica columns and operation at 80 °C

Recently, hydrophilic interaction chromatography (HILIC) has emerged as a valuable orthogonal tool to reversed-phase liquid chromatography (RP-LC) as it allows for resolution of highly polar ionisable compounds. The relationships between separation efficiency, column length and speed of analysis for 4.6 mm ID × 5 μm silica particle columns in HILIC are demonstrated using kinetic plots. The kinetic plots constructed for conventional pressure systems operating at 350 bar and at 30 °C and 80 °C are confirmed using experimental data for different column lengths. Efficiencies of more than 130,000 theoretical plates could be achieved by connecting up to six columns of 25 cm. As expected, a significant gain in analysis speed without loss of efficiency could be obtained by operating at 80 °C compared to 30 °C. The advantages of using long columns in HILIC in combination with elevated column temperature for the pharmaceutical industry are illustrated using test mixtures comprised of commercially available ionisable compounds (including some containing functional groups with potential genotoxic typical structural alerts) as well as real polar ionisable pharmaceuticals.     

Magnetic nanostructures by adaptive twinning in strained epitaxial films

We exploit the intrinsic structural instability of the Fe(70)Pd(30) magnetic shape memory alloy to obtain functional epitaxial films exhibiting a self-organized nanostructure. We demonstrate that coherent epitaxial straining by 54% is possible. The combination of thin film experiments and large-scale first-principles calculations enables us to establish a lattice relaxation mechanism, which is not expected for stable materials. We identify a low twin boundary energy compared to a high elastic energy as key prerequisite for the adaptive nanotwinning. Our approach is versatile as it allows to control both, nanostructure and intrinsic properties for ferromagnetic, ferroelastic, and ferroelectric materials.     

Synthesis,characterization and anticancer activity of new palladacycles derived from chiral α‐diimines

Optically pure α‐diimines quantitatively obtained in solvent‐free conditions starting from 2,3‐butanedione and (S)‐(?)‐1‐phenylethylamine and (S)‐(?)‐1‐(4‐methylphenyl)ethylamine, respectively, yielded the new chiral mono‐Pd complexes 2a–b, which have been partly characterized by IR, ¹H‐ and ¹³C‐NMR spectroscopies along with MS‐FAB⁺ spectrometry. The crystal and molecular structure for palladacycle 2a has been fully confirmed by single‐crystal X‐ray studies. Studies in vitro of 2a–b have displayed growth inhibition against different classes of cancer: leukemia (K‐562 CML), colon cancer (HCT‐15), breast cancer (MCF‐7), central nervous system (U‐251 Glio) and prostate cancer (PC‐3) cell lines. Copyright © 2009 John Wiley & Sons, Ltd.     

The corrections for non-ideal behavior of the epithermal neutron spectrum and the restitution of the simplicity in parametric activation analysis

The errors occurred when α, the parameter that accounts for the non-ideal behavior of the epithermal flux, are neglected, have been evaluated for the determination of twenty elements in biological materials, using. gold and sodium comparators, and zirconium to measure the thermal to epithermal flux ratio (f). Sodium allows the determination of 15 elements, and up to 18 elements can be determined in positions relatively well thermalized by the simultaneous use of gold and sodium comparators, in all the cases with errors ≦2%, when α is not considered. Results obtained for reference materials are presented.     

Diastered and Regiochemical Control in the Functionalization of the Allylic [dbnd] of a Natural 5-(1-Alkenyl)-2-Enono-1,5-Lactone

The diastereo and regioselectivity of the bromohydrination of argentilactona [(5R)-(-)-δ-lactone of 5-hydroxydodeca-Z, Z-2,6-dienoic acid] and the regioselectivity of the aqueous acidic opening of its 65,75 and 6R,7R-epoxides were studied. Although the reactions occurred with low diasterofacial control, the regioselectivity observed in all cases was high, suggesting that the sequences could be of some synthetic value.     

Interpretation of vicinal proton–proton coupling constants of heteroaromatic molecules in terms of topological electron density descriptors

The indirect vicinal proton–proton coupling constants for pyrrole, furan, thiophene and 15 related heteroaromatic compounds were calculated using the Khon–Sham approximation. An analysis of the four Ramsey contributions to the coupling constants was carried out showing that the Fermi contact term is always positive and dominant, although the remaining contributions have a nonnegligible net negative contribution. The trends observed for the proton–proton coupling constants were rationalized in terms of the properties of the electron density. It was found that electron delocalization between the corresponding hydrogen atoms plays a major role on the observed behavior with the charges of the carbon atoms bonded to them and the accompanying geometric variations being also of importance in the coupling mechanism. Copyright © 2010 John Wiley & Sons, Ltd.