Ab initio simulations of the NMR spectra of β-alanine conformers

The NMR shielding and indirect spin-spin coupling constants are calculated for 10 most stable conformers of β-alanine, using the B3LYP/aug-cc-pVTZ-su-1 level. In this study the focus is on determination of conformational effects and the intramolecular hydrogen bond on the NMR parameters for β-alanine conformers. Numerous correlations were detected between geometrical, topological and NMR parameters. The 13C chemical shifts show dependence on intramolecular hydrogen bonds. The 15N chemical shifts seem to be sufficient in supporting the conformational analysis. Some 1J-coupling constant correlate with both the bond critical point electron density and the Laplacian. The vicinal proton-proton 3J-coupling constants show clearly the local arrangements around the respective axes. Therefore, NMR parameters along with the quantum chemical calculations may be able to discriminate between conformers.