Assigning powders to crystal structures by high-resolution 1H–1H double quantum and 1H–13C J-INEPT solid-state NMR spectroscopy and first principles computation. A case study of penicillin G
Nicolas Mifsud, Bénédicte Elena, Chris J. Pickard, Anne Lesage and Lyndon Emsley
We show how powder samples at natural isotopic abundance can be assigned to crystal structures by using high-resolution proton and carbon-13 solid-state NMR spectra in combination with first principles calculations. Homonuclear proton double-quantum spectra in combination with through-bond proton–carbon HSQC spectra are used to assign the NMR spectra. We then show that the proton chemical shifts can be included in the process of assigning the spectra to a crystal structure using first principles calculations. The method is demonstrated on the K salt of penicillin G.