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Surface-mediated nucleation in the solid-state polymorph transformation of terephthalic acid
Gregg T Beckham1, Baron Peters, Cindy Starbuck
1Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Journal of the American Chemical Society
|March 28, 2007
Summary
This study reveals the molecular mechanism for terephthalic acid solid-state polymorph transformation. Nucleation occurs via localized crystal edge growth, driven by supramolecular synthon fluctuations, indicating a nucleation and growth process.
Area of Science:
- Materials Science
- Chemical Physics
- Crystallography
Background:
- Solid-state polymorph transformations are crucial in materials science.
- Understanding nucleation mechanisms is key to controlling material properties.
- Terephthalic acid exhibits complex polymorphic behavior.
Purpose of the Study:
- To elucidate the molecular mechanism of terephthalic acid nucleation during solid-state polymorph transformation.
- To develop and validate a computational model for the reaction coordinate of this transformation.
- To identify the key structural features and dynamics involved in nucleus formation.
Main Methods:
- Development and application of novel computational methods: aimless shooting and likelihood maximization.
- Construction of a reaction coordinate model for two system sizes.
- Validation of the reaction coordinate using committor probability analysis.
Main Results:
- A molecular mechanism for terephthalic acid nucleation is established.
- The transformation initiates via a localized, elongated nucleus at the crystal edge.
- Fluctuations in supramolecular synthons drive nucleus formation.
Conclusions:
- The solid-state polymorph transformation of terephthalic acid follows a nucleation and growth mechanism.
- The developed computational methods provide a robust framework for studying solid-state transformations.
- The findings offer insights into controlling crystal structure and phase transitions.
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