Effect of mixing, concentration and temperature on the formation of mesostructured solutions and their role in the nucleation of DL-valine crystals

Anna Jawor-Baczynska, Barry D. Moore, Jan Sefcik, Barry D. Moore

Research output: Contribution to journalArticle

10 Citations (Scopus)
54 Downloads (Pure)

Abstract

We report investigations on the formation of mesostructured solutions in DL-valine-water-2-propanol mixtures, and the crystallization of DL-valine from these solutions. Mesostructured liquid phases, similar to those previously observed in aqueous solutions of glycine and DL-alanine, were observed using Dynamic Light Scattering and Brownian microscopy, in both undersaturated and supersaturated solutions below a certain transition temperature. Careful experimentation was used to demonstrate that the optically clear mesostructured liquid phase, comprising colloidal mesoscale clusters dispersed within bulk solution, is thermodynamically stable and present in equilibrium with the solid phase at saturation conditions. Solutions prepared by slow cooling contained mesoscale clusters with a narrow size distribution and a mean hydrodynamic diameter of around 200 nm. Solutions of identical composition prepared by rapid isothermal mixing of valine aqueous solutions with 2-propanol contained mesoscale clusters which were significantly larger than those observed in slowly cooled solutions. The presence of larger mesoscale clusters was found to correspond to faster nucleation. Observed induction times were strongly dependent on the rapid initial mixing step, although solutions were left undisturbed afterwards and the induction times observed were up to two orders of magnitude longer than the initial mixing period. We propose that mesoscale clusters above a certain critical size are likely to be the location of productive nucleation events.

Original languageEnglish
Pages (from-to)141-154
Number of pages14
JournalFaraday Discussions
Volume179
Early online date29 Jan 2015
DOIs
Publication statusPublished - 1 Jul 2015

Keywords

  • mesostructured solutions
  • mixing effects
  • concentration effects
  • temperature effects
  • nucleation
  • dynamic light scattering

Fingerprint Dive into the research topics of 'Effect of mixing, concentration and temperature on the formation of mesostructured solutions and their role in the nucleation of DL-valine crystals'. Together they form a unique fingerprint.

Cite this