The Raman spectra of (1 − x)(BMITFSI), xLiTFSI ionic liquids, where 1-butyl-3-methylimidazolium cation (BMI + ) and bis(trifluoromethane-sulfonyl)imide anion (TFSI − ) are analyzed for LiTFSI mole fractions x < 0.4. As expected from previous studies on similar TFSI-based systems, most lithium ions are shown to be coordinated within [Li(TFSI) 2 ] − anionic clusters. The variation of the self-diffusion coefficients of the 1 H, 19 F, and 7 Li nuclei, measured by pulsed-gradient spin-echo NMR (PGSE-NMR) as a function of x, can be rationalized in terms of the weighted contribution of BMI + cations, TFSI − 'free' anions, and [Li(TFSI) 2 ] − anionic clusters. This implies a negative transference number for lithium.

The interactions between the B3 (catechin-4alpha,8-catechin) red wine tannin and the human salivary protein fragment IB7(14) (SPPGKPQGPPPQGG) were monitored by (1)H magic angle spinning NMR, circular dichroism, electrospray ionization mass spectrometry, and molecular modeling. It is found that the secondary structure of IB7(14) is made of a type II helix (collagen helix) and random coil. The central glycine 8 appears to act as a flexible rotula separating two helix II regions. Three tannin molecules tightly complex the peptide, without modifying its secondary structure, but seem to reduce its conformational dynamics. The binding dissociation constant is in the millimolar range. B3 tannins with a "tweezers" conformation bind to the hydrophilic side of the saliva peptide, suggesting that the principal driving forces toward association are governed by hydrogen bonding between the carbonyl functions of proline residues and both the phenol and catechol OH groups. These findings are further discussed in the frame of an astringency phenomenon.