Neutron scattering on a re-entrant binary liquid mixture

Re-entrant supramolecular interactions in inverse-melting α-cyclodextrin·4-methylpyridine·water mixtures: an NMR study

Inverse freezing αCD·4MP·H₂O turns into a gel as αCD loses its solvation shell. First, it loses its interaction with 4MP, and then its solvation by water.

Unconventional density dependence of the stochastic dynamics in an organic liquid

The density dependence of the diffusive rotational and center-of-mass dynamics of 2-methyl-pyridine is investigated by means of the concurrent use of quasielastic neutron scattering and molecular dynamics simulations. The dependence of both translation and rotational diffusion coefficients shows a distinctive change of slope with increasing density taking place about rho=0.975 g/cm3. Such a change in the dynamics can be related to observations made in other liquids composed of oblate-spheroidal particles.

Freezing on heating of liquid solutions

We report a reversible liquid-solid transition upon heating of a simple solution composed of a-cyclodextrine (alpha CD), water, and 4-methylpyridine. These solutions are homogeneous and transparent at ambient temperature and solidify when heated to temperatures between 45 degrees and 75 degrees. Quasielastic and elastic neutron scattering show that molecular motions are slowed down in the solid and that crystalline order is established. The solution "freezes on heating." This process is fully reversible, on cooling the solid melts. A rearrangement of hydrogen bonds is postulated to be responsible for the observed phenomenon.