1 H-NMR spectra were acquired using a Bruker Avance III HD spectrometer equipped with a broad band fluorine observation (BBFO) SmartProbe TM with z-axis gradients (Bruker BioSpin, Billerica, MA, USA) operating at a proton frequency of 500.23 MHz. The 1 H-NMR spectra were recorded using Topspin 3.57 software (Bruker BioSpin) and the Bruker pulse sequence 'noesypr1d' for one-dimensional nuclear Overhauser enhancement spectroscopy. Presaturation was applied to suppress the water signal at 4.704 ppm. The temperature was set to 298 K (25 °C) and the following acquisition parameters were used: 64 scans, 64k data points with a spectral width of 16 ppm, relaxation delay of 1 s, acquisition time of 4 s and mixing time of 0.1 s. Tuning, locking, gaining, shimming and 90° pulse calibration optimization were performed for each sample using the Bruker standard routine. The free induction decay (FID) signals recorded were multiplied by a 0.3-Hz line broadening function prior to Fourier transformation.