title: Deuterium MAS NMR studies of dynamics on multiple timescales: histidine and oxalic acid.
abstract: Deuterium ((2) H) magic-angle spinning (MAS) nuclear magnetic resonance is applied to monitor the dynamics of the exchanging labile deuterons of polycrystalline L-histidine hydrochloride monohydrate-d7 and α-oxalic acid dihydrate-d6 . Direct experimental evidence of fast dynamics is obtained from T1Z and T1Q measurements. Further motional information is extracted from two-dimensional single-quantum (SQ) and double-quantum (DQ) MAS spectra. Differences between the SQ and DQ linewidths clearly indicate the presence of motions on intermediate timescales for the carboxylic moiety and the D2 O in α-oxalic acid dihydrate, and for the amine group and the D2 O in L-histidine hydrochloride monohydrate. Comparison of the relaxation rate constants of Zeeman and quadrupolar order with the relaxation rate constants of the DQ coherences suggests the co-existence of fast and slow motional processes.
authors.affiliation: Laboratoire des BioMolécules, UMR 7203, UPMC/ENS/CNRS, 24, rue Lhomond, 75231 Paris Cedex 05 (France); Sorbonne Universités, UPMC Univ Paris 06, LBM, 4 place Jussieu, 75005, Paris (France); École Normale Supérieure-PSL Research University, Département de Chimie, 24, rue Lhomond, 75005 Paris (France); Institut Curie, 91405 Orsay (France); INSERM U759, 91405 Orsay (France).
authors.forename: Monique
authors.initials: M
authors.lastname: Chan-Huot
authors.forename: Stephen
authors.initials: S
authors.lastname: Wimperis
authors.forename: Christel
authors.initials: C
authors.lastname: Gervais
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Bodenhausen
authors.forename: Luminita
authors.initials: L
authors.lastname: Duma
mesh_terms: D003903:Deuterium / Q000737:chemistry; D006639:Histidine / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D019815:Oxalic Acid / Q000737:chemistry*
chemical_list: D006639:Histidine; D019815:Oxalic Acid; D003903:Deuterium
keywords: NMR spectroscopy; deuterium; magic-angle spinning; molecular dynamics; solid-state structures