title: Nuclear magnetic resonance signaling of molecular chiral information using an achiral reagent.
abstract: Until now NMR spectroscopic detection of guest chirality using an achiral host has not been possible in the absence of a chiral medium or auxiliary since chiral discrimination is principally based on chiral discrimination by host and/or diastereomeric host-guest complex formation. In this paper, we demonstrate that an achiral oxoporphyrinogen works as a host capable of signaling chiral information of alpha-hydroxycarboxylic acids in (1)H NMR spectroscopy. In particular, enantiomeric excess (ee) can be determined by observing the splitting of (1)H NMR resonances of the achiral host. This differs from the case of chiral hosts (shift reagents) where % ee is generally determined from the ratio of peak areas due to diastereomeric host-guest complexes. UV/vis, CD, FT-IR, and NMR spectroscopic investigations suggest that the unusual phenomenon reported here is based on formation of a complex with 1:2 stoichiometry in concert with a protonation-driven tautomerization of the host.
authors: World Premier International Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan.
authors: Atsuomi
authors: A
authors: Shundo
authors: Jan
authors: J
authors: Labuta
authors: Jonathan P
authors: JP
authors: Hill
authors: Shinsuke
authors: S
authors: Ishihara
authors: Katsuhiko
authors: K
authors: Ariga
mesh_terms: D002942:Circular Dichroism; D009682:Magnetic Resonance Spectroscopy; D008333:Mandelic Acids / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D010100:Oxygen / Q000737:chemistry; D011165:Porphyrinogens / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D008333:Mandelic Acids; D011165:Porphyrinogens; C037938:mandelic acid; D010100:Oxygen