Exploring the Stability and Disorder in the Polymorphs of L-Cysteine through Density Functional Theory and Vibrational Spectroscopy.

ABSTRACT: Static and dynamic density functional calculations are reported for the four known polymorphs of l-cysteine. Static calculations are used to explore the relative free energies (within the harmonic approximation) of the polymorphs as a function of pressure. An important feature of the structural differences between the polymorphs is shown to be the dihedral angle of the C-C-S-H bond. It is shown that, by varying this angle, it is possible to move between hydrogen bonding motifs S-H···S and S-H···O in all four polymorphs. The energetics for dihedral angle rotation are explored, and the barriers for rotation between the hydrogen bonding motifs have been calculated for each polymorph. Two possible models for the experimental disorder observed in Form I at room temperature are exp

SUBMITTER: Kendrick J 

PROVIDER: S-EPMC10401577 | biostudies-literature | 2023 Aug

REPOSITORIES: biostudies-literature