α-Glycine under high pressures: a Raman scattering study

Application of instrumented nanoindentation in preformulation studies of pharmaceutical active ingredients and excipients

“…It was shown that E was strongly facet dependent and correlated with the underlying hydrogen-bonding network (105). Such a large E of amino acid crystals had been previously obtained in high-pressure diffraction measurements (106,107). The determined E values of amino acids are remarkably high for molecular solids and suggest the hydrogen-bond network design as a pattern for rational design of ultra-stiff molecular solids (105).…”

High-pressure diffraction studies of molecular organic solids. A personal view

“…An interesting example of kinetic control is provided by the polymorphs of glycine, which show a very different response to pressure. The structure of -glycine (P2 1 /n) is stable with respect to pressure-induced phase transitions at least up to 23 GPa (Murli et al, 2003) -glycine (Pn) in a wide pressure range starting from about 3.5 GPa (Boldyreva, 2003b;Boldyreva et al, 2003;Boldyreva, Ivashevsyaya et al, 2004, which then converts into the form on decompression down to 0.6 GPa (Goryainov et al, 2006) (Fig. 7); the single crystals of -glycine are destroyed during the À transition.…”

Multicomponent organic crystals at high pressure

“…Depending on the way how the zwitterions are connected to give one of the three polymorphs known at ambient conditions (α-glycine [37,38]), β-glycine [39], γ-glycine [40]), on increasing pressure the crystal structure can undergo a reversible phase transition not destroying the single crystal already at a low pressure (β-polymorph, 0.76 GPa [41][42][43]), a reconstructive phase transition from a single crystal to powder at a higher pressure (γ-polymorph, 3.5 GPa [44][45][46]), or remains incredibly robust (α-polymorph, at least up to 23 GPa [47]). It was assumed that the remarkable stability of the α-polymorph is provided by the centrosymmetric double layers linked by NH … O hydrogen bonds.…”