Low Temperature Dependence in 1H CRAMPS & 13C CP/MAS ssNMR Spectra of Alanine Enantiomers
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1H RAMPS solid state NMR and 13C CP/MAS spectra of D- and L- alanine crystals were measured at temperature ranging from 220K to 295K. Some major points are as follows: (1)alpha-H and protons in the methyl group showed a spin-spin coupling effect as temperature went down in the 1H- MAS spectra of D-alanine. (2) In the 1H CRAMPS spectra, peak widths of alpha-H and beta-H showed a different trend between alanine enantiomers when temperature varied.(3) The dynamic behavior of 13C spectra showed an obvious change around 250K, which was supposed as a phase transition in alanine crystal. In the discussion section, we give these experimental phenomena a possible explanation related to chirality.
this paper has been withdrawn by the authors, because new results have been discovered and this paper has to be rewritten
this paper has been withdrawn by the authors, because new results have been discovered and this paper has to be rewritten