“…Cadars et al then argued based on their 1 H double quantum (DQ) MAS NMR spectroscopy results that even within a largely ordered structure, a small concentration of defects, for example, MgAl 2 OH, could exist in Al rich LDHs. [ 13 ] Cation ordering was further supported by the 25 Mg NMR data obtained by Sideris et al at an ultrahigh magnetic fi eld, where it was argued that the presence of defects in some samples was likely a consequence of the synthesis method. [ 14,15 ] Large 1 H-1 H homonuclear dipolar couplings are present in these systems, [ 17 ] and ultrafast spinning rates (i.e., >40 kHz) [ 18 ] were required for the NO 3 − -containing LDHs to allow resolution of the major resonances.…”