Tunable-alignment chiral system based on gelatin for NMR spectroscopy

We demonstrate NMR spectral separation of enantiomers of DL-alanine in the chiral anisotropic medium of variably stretched gelatin. This is done in an apparatus that employs gelatin gel in an elastic silicone-rubber tube. There are two adjustable properties of the gels, their concentration and their extension factor. Concentration has a far larger effect in manifesting quadrupolar and dipolar splittings and fine-tuning, to a specified splitting-value or to overcome peak overlap, is achieved by varying the extension of the gel. We show that alanine enantiomers can be distinguished by H-1, H-2, and C-13 NMR. This valuable spectral outcome is not specific to alanine and is a general property of gelatin gels, so they constitute a notable advance on previous related methods using liquid crystals.