Hydration modes of an amphiphilic molecule: NMR, FTIR, and theoretical study of the interactions in the water-lutidine system.
Using (1)H and (13)C NMR spectra and relaxations, PFG NMR diffusion measurements, FTIR spectra, and quantum-chemical structure predictions and optimizations on the MP2/6-31G(d) level, we have studied interactions between water (W) and lutidine (2,6-dimethylpyridine, L) in a wide range of ratios. At low W content up to 35%, W was found to bind to L by an O-H***N hydrogen bond and form transient L-W aggregates containing two to four L molecules in cooperation with two to three other W molecules. At higher W content, these aggregates are gradually cleaved to single L molecules enwrapped by a hydration shell anchored in an O-H***N hydrogen bond. At all compositions of the mixture, the various hydrate forms are in fast mutual exchange with a correlation time on the order of 1 x 10(-5) s.
Kríz
Jaroslav
J
Institute of Macromolecular Chemistry AS CR, 162 06 Prague, Czech Republic.
Dybal
Jirí
J
Tuzar
Zdenek
Z
Kadlec
Petr
P