Effects of hydrostatic pressure on amorphous chiral materials: Impact on homochiral or heterochiral H-bond sequences
Résumé
High pressure effects on static dielectric permittivity of homochiral and heterochiral N-acetyl-α-methyl-benzylamine
(Nac-MBA) were investigated. For homochiral composition, the static permittivity increases of 178%
with pressure at T = 388 K. Interestingly, as pressure continued increasing, εS drastically collapsed to reach ε∞ =
3 ± 0.3. In the case of heterochiral composition, the static permittivity increases with pressure (in the same
magnitude order as the pure enantiomer), and reaches a constant value depending on the isothermal temperature.
Thus, the size of the H-bond aggregates is highly pressure sensitive, increasing up to a level that crystallization
becomes unavoidable. For heterochiral composition, this process may be kinetically time consuming
since the initial heterochiral H-bond aggregates need to be surrounded by their suitable neighbors in order to
fulfilled the crystalline packing. The initial H-bond sequences are the precursors of the future crystalline
arrangement under pressure application.
Domaines
Physique [physics]Origine | Fichiers éditeurs autorisés sur une archive ouverte |
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