Sulle modificazioni strutturali presentate da films di glioma in presenza di vapor acqueo. Nota II

Bertoluzza, Alessandro ; Bonino, Giovanni Battista ; Fognano, Concezio

Atti della Accademia nazionale dei Lincei. Rendiconti della Classe di scienze fisiche, matematiche e naturali, Série 8, Tome 50 (1971) no. 3, pp. 325-336

Résumé

Infrared spectra of glycine films in presence of water vapour show considerable modifications which depend upon the preparation conditions of the films and also upon the water vapour pressure. A glycine film, obtained by slow sublimation, is transformed into the $\alpha$ modification (only at a fixed water vapour pressure), while a glycine film obtained by rapid sublimation is transformed into both $\alpha$ and $\gamma$ modifications (at a fixed water vapour pressure), and into $\gamma$ modification only (at a satured water vapour pressure). These transformations have been pointed out by means of the i.r. spectra of $\alpha$ and $\gamma$ glycine modifications. It has also been supposed that a glycine film (obtained either by rapid or by slow sublimation) corresponds to the $\beta$ modification; the behaviour of the i.r. spectra between 3100-3200 cm-1 supports such a hypothesis. There has also been suggested a mechanism for $\beta \to \alpha$, $\beta \to \gamma$ glycine transformations; such a mechanism involves water vapour, the structures of the polymorphic glycine modifications and the structural properties of the films.