Experiments were performed on 400 MHz and 700 MHz Bruker Avance Neo systems. For all samples the recycling delays between transients were set to 60 s corresponding to at least three T 1 periods. C pulse nutation frequencies were given by ∼13.9 kHz at 9.4 T, and ∼10.7 kHz at 16.5 T. T 1 measurements used a single transient for each data point. T S measurements (see below) used averaging over 1 to 8 transients in order to achieve a signal-to-noise of ∼16 for the first data point. The NMR signals were sampled with 131k data points and a spectral width of 146 ppm.