Determination of the absolute configuration of 2-hydroxyglutaric acid and 5-oxoproline in urine samples by high-resolution NMR spectroscopy in the presence of chiral lanthanide complexes

Lanthanide Class of a Trinuclear Enantiopure Helical Architecture Containing Chiral Ligands: Synthesis, Structure, and Properties

“…, which is about 2 ) species. A spectrum void of signals is registered when a racemic mixture of the ligand was employed.…”

“…The role of the enantiopure ligand in this case is to provide the chiral environment necessary to render the enantiotopic nuclei of the substrates diastereotopic. The absolute configuration of a wide range of compounds [1,2] from simple organic molecules or metabolites to proteins has been determined in this way. Lanthanide complexes are also Abstract: The pinene-bipyridine carboxylic derivatives (+)-and (À)-HL, designed to form configurationally stable lanthanide complexes, proved their effectiveness as chiral building blocks for the synthesis of lanthanidecontaining superstructures.…”

“…[53] The bipyridyl chromophores in set S' are uncoordinated and hence free to rotate; however, the contribution from set S' may not be as negligible as one may think from the conformational flexibility. 2 ), additional spectroscopic information is provided by CPL spectroscopy. This technique is the emission analogue of CD and probes the chirality of the metal-centered excited states.…”

Analysis of pD‐Dependent complexation of N‐benzyloxycarbonylaminophosphonic acids by α‐cyclodextrin. Enantiodifferentiation of phosphonic acid pKa values

“…The most popular current analytical methods used for the direct separation of stereoisomers are chromatographic (e.g., gas chromatography, high performance liquid chromatography, thin layer chromatography, and supercritical fluid chromatography) [1][2][3][4][5] and electrokinetic (e.g., capillary electrophoresis, capillary electrochromatography, micellar electrokinetic chromatography). [6][7][8][9][10][11][12] Nuclear magnetic resonance spectroscopy ranks among the nonseparation techniques used for determination of optical purity [13][14][15][16] but it possesses an important additional advantage over all others methodologies. NMR provides considerable information about the structure and dynamics of the diastereoisomeric complexes formed during the separation process.…”

NMR-based Enantiodifferentiation of Chiral trans-2-Phenylcyclopropane Derivatives Using a Chiral Lanthanide Shift Reagent

“…Care is required in determining absolute configurations based on empirical correlations of chemical shifts in the presence of chiral shift reagents. While several studies have determined absolute configurations based on ΔΔδ, [11][12][13][14][15][16][17][18][19] there are cases in which the sign of ΔΔδ changes within the same series of compounds. 20,21 In the current study, absolute configurations are considered accurate because the differences in the patterns of R and S enantiomeric methyl chemical shifts (ΔΔδ) were the same (i.e., the downfield chemical shift of the S enantiomer matches the upfield chemical shift of the R enantiomer).…”