Behavior of intermolecular interactions in alpha-glycine under high pressure
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Pressure-response on the crystal structure of deuterated alpha-glycine was investigated at room temperature, using powder and single-crystal X-ray diffraction, and powder neutron diffraction measurements under high pressure. No phase change was observed up to 8.7 GPa, although anisotropy of the lattice compressibility was found. No significant changes in the compressibility and the intramolecular distance between non-deuterated alpha-glycine and deuterated alpha-glycine were observed. Neutron diffraction measurements indicated the distance of the intermolecular D center dot center dot center dot O bond along with the c-axis increased with compression up to 6.4 GPa. The distance of another D center dot center dot center dot O bond along with the a-axis decreased with increasing pressure and became the shortest intermolecular hydrogen bond above 3 GPa. In contrast, the lengths of the bifurcated N-D center dot center dot center dot O and C-D center dot center dot center dot O hydrogen bonds, which are formed between the layers of the alpha-glycine molecules along the b-axis, decreased significantly with increasing pressure. The decrease of the intermolecular distances resulted in the largest compressibility of the b-axis, compared to the other two axes. The Hirshfeld analysis suggested that the reduction of the void region size, rather than shrinkage of the strong N-D center dot center dot center dot O hydrogen bonds, occurred with compression. Published by AIP Publishing.
- Journal of chemical physics
Journal of chemical physics 148(4), 044507, 2018-01-28
American Institute of Physics (AIP)