Rigaku Europe SE

Iron porphyrin complexes, which were linked via a para-phenylethynyl group to a chiral scaffold with a lactam binding site, were probed as catalysts in the enantioselective epoxidation of 4-(ω-alkenyl)-quinolones. It was found that the 3-butenyl group in the substrate accounts for the highest enantioselectivity (up to 44% ee) and the absolute configuration of an oxirane product was elucidated by electron diffraction. A two-point hydrogen bond of the substrate to the catalyst is likely responsible for enantioface differentiation at a remote position. The study shows chirality transfer to be possible via four nonstereogenic carbon atoms between the binding site of the substrate and its reactive C=C double bond.

Many organic compounds, including medicines, have preferred orientation, affected by the sample-preparation methods, which might cause problems in x-ray diffraction anal.To arrive at accurate and correct x-ray diffraction anal. results of such compounds, we need a specially designed diffractometer, or special techniques to avoid the preferred-orientation effect.X-ray fluorescence (XRF) anal. is liable to cause misunderstandings that it is weak for analyzing organic compounds, since they are composed in mainly of light elements.The recent progress of synthesized multilayer mirror technol. has brought new possibilities in x-ray diffraction and XRF analyses.The parallel beam method has been widely used in x-ray diffraction anal. due to its high resolution and sufficiently good brilliance.In XRF anal., specially designed synthesized multi-layer mirrors enable us to carry out low-concentration light elemental anal. such as for boron, carbon, oxygen, and so on.In the present work we evaluated the availability of recent progress related to the synthesized multilayer mirror technol. in x-ray diffraction and XRF techniques for organic compounds, including medicines, by performing comparative analyses of acetylsalicylic acid based analgesic antipyretic drugs.

An approach to visualize the accessible reciprocal space accounting the goniometer angles limitation and the resolution element in the reciprocal space is presented.The shapes of the accessible reciprocal space region for coplanar and non-coplanar geometries are given employing the addnl. degree of freedom provided by detector arm.The examples of the resolution elements in different points of the reciprocal space are shown.The equations obtained permit to find these regions and to calculate the exptl. geometry to obtain the diffraction from any accessible reflections, which makes a further extension of previously reported methods.The introduced algorithm has been testified by exptl. measurements of reciprocal space maps in coplanar and non-coplanar geometries.The examples of the resolution elements in different points of the reciprocal space are calculated to illustrate the method proposed.