NMR study of the interaction of monomeric and polymeric chiral surfactantswith (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-undecyleny l-L-valine-L-leucine and sodium N-undecylenyl-L-leucine-L-valine, and relat ed polymers is investigated by high-field one (1D)- and two-dimensional (2D ) nuclear magnetic resonance (NMR) spectroscopy. A general property of the high-resolution H-1 NMR spectra of monomeric CS in 90% H2O/10% D2O is the a ppearance of downfield well-resolved chemical shift signals corresponding t o the alpha (alpha H) protons of valine (Val alpha H) and leucine (Leu alph a H) amino acid residues. The remaining skeletal protons resonate in the re gion 0.5-2.5 ppm, giving rise to an envelope of poorly resolved chemical sh ifts. The H-1 NMR signals of (R)- and (S)-BNDHP were enantiomerically separ ated into six sets of peaks in the presence of CS. The conformational analy sis by means of nuclear Overhauser effect spectroscopy experiments indicate s that the CS molecules adopt folded conformations in aqueous solution. The multiple interactions of(S)-BNDHP and CS obtained from intermolecular rota ting frame Overhauser effect NMR spectroscopy is direct evidence on the mec hanism of chiral recognition in aqueous media.