Effect of pressure on crystalline L- and DL-serine: revisited by a combined single-crystal X-ray diffraction at a laboratory source and polarized Raman spectroscopy study.

Information on the effect of pressure on hydrogen bonds, which could be derived from single-crystal X-ray diffraction at a laboratory source and polarized Raman spectroscopy, has been compared. L-Serine and DL-serine were selected for this case study. The role of hydrogen bonds in pressure-induced phase transitions in the first system and in the structural stability of the second one are discussed. Non-monotonic distortion of selected hydrogen bonds in the pressure range below ~1-2 GPa, a change in the compression mechanism at ~2-3 GPa, and the evidence of formation of bifurcated N-H...O hydrogen bonds in DL-serine at ~3-4 GPa are considered.