NMR Study of the Interaction of Monomeric and Polymeric Chiral Surfactants with (R)- and (S)-1,1‘-Binaphthyl-2,2‘-diyl Hydrogen Phosphate

Chiral discrimination of enantiomers of 1,1‘-binaphthyl-2,2‘-diyl hydrogen phosphate (BNDHP) by monomeric chiral surfactants (CS), sodium N -undecylenyl- l -valine- l -leucine and sodium N-undecylenyl- l -leucine- l -valine, and related polymers is investigated by high-field one (1D)- and two-dimensional (2D) nuclear magnetic resonance (NMR) spectroscopy. A general property of the high-resolution 1 H NMR spectra of monomeric CS in 90% H 2 O/10% D 2 O is the appearance of downfield well-resolved chemical shift signals corresponding to the alpha (αH) protons of valine (ValαH) and leucine (LeuαH) amino acid residues. The remaining skeletal protons resonate in the region 0.5−2.5 ppm, giving rise to an envelope of poorly resolved chemical shifts. The 1 H NMR signals of ( R )- and ( S )-BNDHP were enantiomerically separated into six sets of peaks in the presence of CS. The conformational analysis by means of nuclear Overhauser effect spectroscopy experiments indicates that the CS molecules adopt folded conformations in aqueous solution. The multiple interactions of ( S )-BNDHP and CS obtained from intermolecular rotating frame Overhauser effect NMR spectroscopy is direct evidence on the mechanism of chiral recognition in aqueous media.