Hydrogen‐bonding interactions in fully deuterated α‐glycine at high pressures

Recent spectroscopic investigations of various amino acids report intriguing high‐pressure and low‐temperature behavior of NH₃⁺ groups and their influence on various hydrogen bonds in the system. In particular, the variation of the intensity of NH₃⁺ torsional mode at different temperatures and pressures has received much attention. We report here the first in situ Raman investigations of fully deuterated α‐glycine up to ～20 GPa. The discontinuous changes in COO^? and ND₃⁺ modes across ～3 GPa indicate subtle structural rearrangements in fully deuterated α‐glycine. The decrease in the intensity of ND₃⁺ torsional mode is found to be similar to that of undeuterated α‐glycine. The pressure‐induced stiffening of N? D and CD₂ stretching modes are discussed in the context of changes in the hydrogen‐bonding interactions. Copyright © 2011 John Wiley & Sons, Ltd.