Quantification of enantiomeric excess by 1H-detected heteronuclear refocusing and homonuclear multiple quantum NMR experiments

The ω1-heterodecoupled-13C-filtered proton detected NMR experiments are reported for the accurate quantification of enantiomeric excess in chiral molecules embedded in chiral liquid crystal. The differential values of both 1H–1H and 13C–1H dipolar couplings in the direct dimension and only 1H–1H dipolar couplings in the indirect dimension enable unraveling of overlapped enantiomeric peaks. The creation of unequal 13C-bound proton signal for each enantiomer in the INEPT block and non-uniform excitation of coherences in homonuclear multiple quantum experiments do not yield accurate quantification of enantiomeric excess. In circumventing these difficulties, a coupling dependent intensity correction factor has been invoked.