Hydrogen bonds in crystalline d-alanine: diffraction and spectroscopic evidence for differences between enantiomers

Abstract

Enantiomeric amino acids have specific physiological functions in complex biological systems. Systematic studies focusing on the solid-state properties of d-amino acids are, however, still limited. To shed light on this field, structural and spectroscopic studies of d-alanine using neutron powder diffraction, polarized Raman scattering and ab initio calculations of harmonic vibrational frequencies were carried out. Clear changes in the number of vibrational modes are observed as a function of temperature, which can be directly connected to variations of the N—D bond lengths. These results reveal dissimilarities in the structural properties of d-alanine compared with l-alanine.

Keywords

• chirality
• structure analysis
• configurational change
• density-functional-theory-based methods
• phase transitions
• intermolecular interactions
• properties of solids
• hydrogen bonding
• materials science