Dataset Information

Redetermined crystal structure of ?-dl-me-thio-nine at 320?K.

ABSTRACT: The structure of ?-dl-me-thio-nine, C5H11NO2S, in the space group C2/c, is here confirmed to be fully ordered all the way up to the phase transition at approximately 326?K, where displacive sliding of mol-ecular bilayers gives the disordered P21/c ? form [data at 340?K; Görbitz (2014). Acta Cryst. E70, 341-343]. The geometry of hydrogen bonds in LD-LD hydrogen-bonding patterns [Görbitz et al. (2009). Acta Cryst. B65, 393-400] at the hydro-philic core of each mol-ecular bilayer are virtually unperturbed by the phase shift, but the C-C-S-C torsion angle of the side chain changes from trans at 320?K to gauche+ for the major conformation at 340?K.

SUBMITTER: Gorbitz CH

PROVIDER: S-EPMC4459326 | biostudies-literature | 2015 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Redetermined crystal structure of β-dl-me-thio-nine at 320 K.

Görbitz Carl Henrik CH Paulsen Jan Christian JC Borgersen Jon J

Acta crystallographica. Section E, Crystallographic communications 20150513 Pt 6

The structure of β-dl-me-thio-nine, C5H11NO2S, in the space group C2/c, is here confirmed to be fully ordered all the way up to the phase transition at approximately 326 K, where displacive sliding of mol-ecular bilayers gives the disordered P21/c α form [data at 340 K; Görbitz (2014). Acta Cryst. E70, 341-343]. The geometry of hydrogen bonds in LD-LD hydrogen-bonding patterns [Görbitz et al. (2009). Acta Cryst. B65, 393-400] at the hydro-philic core of each mol-ecular bilayer are virtually unpe ...[more]

PMID: 26090187

Similar Datasets

Project description:Understanding of solid-to-solid phase transition mechanisms in polymorphic systems is of critical importance for rigorous control over polymorph purity in the pharmaceutical industry to achieve the desired bioavailability and efficacy of drugs. Ubiquitous defects in crystals may play an important role in the pathways of phase transitions. However, such effects remain poorly understood. Here, the effects of crystal defects on the solid-to-solid phase transformations between dl-me-thio-nine polymorphs α and β are investigated by means of experimental and computational approaches. Thermal analyses of polycrystalline powders show two endothermic peaks in the α-to-β phase transition (and two exothermic peaks for the reverse transition), in contrast with one thermal event observed for single crystals. Variable-temperature 1D and 2D Raman spectra, as well as powder X-ray diffraction patterns, reveal the appearance of two peaks that can attributed to a two-step phase transition, and the extent of the second-step phase transition increases with milling time (or defect density). Quantification of transition kinetics unveils a remarkably higher energy barrier in the second-step phase transition than in the first, proceeding by the cooperative molecular motion pathway. The good linear fitting on the kinetic data by the Jeziorny model suggests that the second-step transition follows the nucleation and growth mechanism. Molecular dynamics simulations were also conducted to understand the role of crystal defects in the solid-state phase transition by tracking the atomic distribution and hydrogen bond lifetime during the transition. It was found that the increasing defect density hinders the propagation of cooperative molecular motion, leading to a combined transition mechanism involving both cooperative motion and nucleation and growth. This study highlights the significant impact of crystal defects on solid-state phase transitions, and the two-step transition mechanism postulated may be universal given the ubiquitous presence of defects in crystalline materials.

Dataset Information

Redetermined crystal structure of ?-dl-me-thio-nine at 320?K.

Publications

Redetermined crystal structure of β-dl-me-thio-nine at 320 K.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets