1 H and 13 C NMR spectra were recorded on a 500 MHz Bruker AV III equipped with a DCH cryoprobe (Ava500). All DOSY experiments were performed using bipolar gradient pulses for diffusion with two spoil gradients (ledbpg2s.compensated) pulse sequence. The sequence was carried out under automated conditions where the duration of the magnetic field pulse gradient (δ) was 1.5 ms and the diffusion time (∆) was 100 ms. Typically in each PFG NMR experiment, a series of 16 spectra on 32 K data points were collected and the eddy current delay (Te) was set to 5 ms in all experiments. The pulse gradients (g) were incremented from 2 to 95% of the maximum gradient strength in a linear ramp. The temperature was set and controlled at 300 K with an air flow of 400 l h -1 in order to avoid any temperature fluctuations due to sample heating during the magnetic field pulse gradients.