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Configurational Isomers (configurational + isomer)

Distribution by Scientific Domains

Chemistry	100%

Selected Abstracts

Configurational Isomers of a Stilbene-Linked Bis(porphyrin) Tweezer: Synthesis and Fullerene-Binding Studies

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 35 2009
Maher Fathalla
Abstract A new stilbene-tethered bis(porphyrin) tweezer 5 has been synthesized through a Sonogashira cross-coupling reaction. The tweezer exists as two configurational isomers [(Z) + (E)], which have distinct cavity sizes. Fullerene-binding studies show that the (Z) isomer of the tweezer has a significantly higher affinity toward both C60 and C70 compared to the (E) congener. In addition, the (Z) , (E) photoisomerization of tweezer 5 is also discussed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

Analysis of isomeric tropane alkaloids from Schizanthus grahamii by very fast gas chromatography

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 1 2006
Stefan Bieri
Abstract This study presents a very fast GC analysis applied for the baseline separation of isomeric tropane alkaloids extracted from the stem-bark of Schizanthus grahamii (Solanaceae). The work provided a challenging application where isothermal analysis in conjunction with very short narrow bore columns (3 m×100 ,m ID and 1.5 m×50 ,m ID) was particularly suited for the speeding up. Experimental parameters were used in the optimisation steps, including selection of stationary phase, temperature, internal column diameter and optimal practicable gas velocity. Some considerations about sample injection in fast isothermal analysis are also briefly presented. Finally, the investigated approach allowed a very fast baseline separation of four positional and configurational isomers in less than 9 s. [source]

Online coupling of enantioselective capillary gas chromatography with proton nuclear magnetic resonance spectroscopy

CHIRALITY, Issue 9 2010
Maximilian Kühnle
Abstract The hyphenation of enantioselective capillary gas chromatography and mass spectrometry is not always sufficient to distinguish between structural isomers, thus requiring peak identification by NMR spectroscopy. Here the first online coupling of enantioselective capillary gas chromatography with proton nuclear resonance spectroscopy is described for the unfunctionalized chiral alkane 2,4-dimethylhexane resolved on octakis(6- O -methyl-2,3-di- O -pentyl)-,-cyclodextrin at 60°C. NMR allows constitutional and configurational isomers (diastereomers and enantiomers) to be distinguished. Enantiomers display identical spectra at different retention times, which enable an indirect identification of these unfunctionalized alkanes. The presented method is still at an early development stage, and will require instrumental optimization in the future. Chirality 2010. © 2010 Wiley-Liss, Inc. [source]