Discrimination of 13C NMR signals in solid material with liquid-like behavior presenting residual dipolar proton-proton homonuclear interactions:: application on seeds

In this communication, we propose, a modified spin echo fourier transform (SEFT) experiment run under magic angle spinning (MAS) to obtain structural informations of the liquid-like domains inside complex organic materials. It includes a proton-proton dipolar decoupling such as BLEW12 or Lee-Goldburg sequence just after the 180degrees C-13 refocusing pulse and short echo delays are used in order to overcome T-2 relaxation. This very easy implemented sequence allows a clear discrimination among fast relaxing C-13 signals between those with a pure liquid-like behavior and those presenting residual proton-proton dipolar coupling. The interests of the sequence, combined with other classical NMR experiments, are illustrated on whole vegetable seeds that represent an example of a complex material. (C) 2003 Elsevier Science (USA). All rights reserved.