A great number of scans have been accumulated in order to get high-quality spectra from whose valuable but small three- and four-spin NOE effects can be easily visualized. In addition, such indirect NOEs present maximum intensity when using large mixing times and, for this reason, all experiments have been recorded using a mixing itme of 1 second except the last spectrum which was recorded with 2 seconds.

The selective 180 pulse in the DPFGE sandwich was set between 20-80 ms as a function of the required selectivity. In all cases, a 1% truncated gaussian shape was applied.