1H NMR analysis was performed by a Bruker AVANCE III 600 MHz NMR spectrometer at 298.15K. The samples were analyzed by pre-saturated pressed water peak pulse sequence noesypr1d ([RD-90°-t1-90°-tM-90°-ACQ]). Relaxation delay was set as 3 s, t1 4 μs, tM 120 ms, sampling time 1.64 s. Two hundred fifty-six free induction decays (FIDs) were collected by TOPSPIN software. The data point at 32 K was kept and adjusted to 64 K with spectral width 10 kHz. Spectral data were acquired from Fourier transform, by a window from all FIDs multiplying exponential function of line width 1 Hz.