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On the origin of surface imposed anisotropic growth of salicylic and acetylsalicylic acids crystals during droplet evaporation
Journal of Molecular Modeling (2015)
  • Maciej Przybyłek, Nicolaus Copernicus University of Torun
  • Piotr Cysewski, Nicolaus Copernicus University of Torun
  • Maciej Pawelec, Nicolaus Copernicus University of Torun
  • Dorota Ziółkowska, University of Technology and Life Sciences in Bydgoszcz
  • Mirosław Kobierski, University of Technology and Life Sciences in Bydgoszcz
Abstract
In this paper droplet evaporative crystallization of salicylic acid (SA) and acetylsalicylic acid (ASA) crystals on different surfaces, such as glass, polyvinyl alcohol (PVA), and paraffin was studied. The obtained crystals were analyzed using powder X-ray diffraction (PXRD) technique. In order to better understand the effect of the surface on evaporative crystallization, crystals deposited on glass were scraped off. Moreover, evaporative crystallization of a large volume of solution was performed. As we found, paraffin which is non-polar surface promotes formation of crystals morphologically similar to those obtained via bulk evaporative crystallization. On the other hand, when crystallization is carried out on the polar surfaces (glass and PVA), there is a significant orientation effect. This phenomenon is manifested by the reduction of the number of peaks in PXRD spectrum recorded for deposited on the surface crystals. Noteworthy, reduction of PXRD signals is not observed for powder samples obtained after scraping crystals off the glass. In order to explain the mechanism of carboxylic crystals growth on the polar surfaces, quantum-chemical computations were performed. It has been found that crystal faces of the strongest orientation effect can be characterized by the highest surface densities of intermolecular interactions energy (IIE). In case of SA and ASA crystals formed on the polar surfaces the most dominant faces are characterized by the highest adhesive and cohesive properties. This suggests that the selection rules of the orientation effect comes directly from surface IIE densities.
Keywords
  • Acetylsalicylic acid,
  • Crystal morphology,
  • Droplet evaporative crystallization,
  • Intermolecular interactions,
  • Powder x-ray diffraction,
  • Salicylic acid
Publication Date
2015
DOI
10.1007/s00894-015-2599-z
Citation Information
Maciej Przybyłek, Piotr Cysewski, Maciej Pawelec, Dorota Ziółkowska, et al.. "On the origin of surface imposed anisotropic growth of salicylic and acetylsalicylic acids crystals during droplet evaporation" Journal of Molecular Modeling Vol. 21 Iss. 3 (2015)
Available at: http://works.bepress.com/maciej-przybyek/17/