Pressure-induced phase transitions in crystalline l-serine studied by single-crystal and high-resolution powder X-ray diffraction

High Pressure Raman Spectra of Amino Acid Crystals

“…Study of Ref. (Boldyreva et al, 2006b) confirms the phase transition previously reported in Ref. (Moggach et al, 2005), although with a transition pressure value of ~ 5.3 GPa, and points the existence of another phase transition at 7.8 GPa.…”

“…Other modifications above 3 GPa were also observed but no X-ray diffraction experiment was performed up to now, which would confirm the occurrence of eventual phase transition undergone by L-threonine crystal. L-serine was also investigated under high pressure conditions (Boldyreva et al, 2005b(Boldyreva et al, , 2006a(Boldyreva et al, , 2006bMoggach et al, 2005Moggach et al, , 2006. From x-ray diffraction measurements (Moggach et al, 2005) it was observed that at ~ 4.8 GPa the crystal undergoes a phase transition with changes in the hydrogen bond network: while the low pressure phase is characterized by OH…OH hydrogen bond chains, in the high pressure phase it is observed shorter OH…carboxyl interactions.…”

Multicomponent organic crystals at high pressure

“…As pressure increases, a cooperative rotation of the side chains results in a structural phase transition at about 5 GPa, so that new OH … O hydrogen bonds between the side chains and the terminal carboxy-groups are formed [15,77]. As pressure increases further, the side chains rotate at about 8 GPa once again to form a new phase with additional bifurcated hydrogen bonds [15,78,79]. The two reversible phase transitions preserve the single crystals intact, and the interface propagates rapidly through the crystal along one of the crystallographic directions.…”

“…Such an example is provided by a comparison of the effect of pressure on L-and DLserine [15,[74][75][76][77][78][79], L-serine monohydrate [80,81], and on bis-DL-serinium oxalate dihydrate [82].…”

“…The information on the response of structures of molecular crystals is relevant also for understanding the conformational stability and dynamics of biopolymers, since the latter are hold by the same types of hydrogen bonds as the crystals of amino acids, carboxylic acids, and other organic molecules. Though the charge assisted H-bonds in amino acid crystals are stronger than those between amino acid residues in a protein, many phenomena (such as, e.g., self-trapping [12,13], rearrangement of 2D-and 3D-networks built of these chains [1,2,14], cooperative "opening and closing" of serine-zippers [1,2,14,15]) are observed in the crystalline amino acids, as well as in proteins. The values of the compressibility of H-bonds obtained for the crystals of amino acids and for proteins are of the same order of magnitude [16].…”