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Molecular Dynamic Simulation of D-Mannitol Polymorphs in Solid State and in Solution Relating With Spontaneous
Weiyi Su1, Ying Zhang1, Jiangman Liu1
1School of Chemical Engineering, Hebei University of Technology, Tianjin 300130, China; National-Local Joint Engineering Laboratory for Energy Conservation of Chemical Process Integration and Resources Utilization, Tianjin 300130, China.
Journal of Pharmaceutical Sciences
|January 26, 2020
Summary
Molecular dynamics simulations reveal how D-mannitol polymorphs form. Different dimer structures in supersaturated solutions correlate with specific D-mannitol crystal forms (alpha, beta, delta), explaining polymorphic nucleation.
Area of Science:
- Physical Chemistry
- Materials Science
- Crystallography
Background:
- D-mannitol exhibits polymorphism, with different crystal forms (alpha, beta, delta) observed.
- Previous studies indicated that varying supersaturation levels influence which D-mannitol polymorphs nucleate.
- Understanding the microscopic mechanisms behind polymorphic nucleation is crucial for controlling crystallization.
Purpose of the Study:
- To investigate the polymorphic nucleation of D-mannitol using molecular dynamics simulations.
- To microscopically understand the role of molecular conformation and solution properties in D-mannitol crystallization.
- To correlate specific dimer structures in supersaturated solutions with the formation of different D-mannitol polymorphs.
Main Methods:
- Molecular dynamics simulations were employed to study D-mannitol in both solid and aqueous solution states.
- Analysis of molecular structure and conformation of three D-mannitol polymorphs in their unit cells.
- Investigation of D-mannitol molecule properties (monomers vs. dimers) in unsaturated and supersaturated aqueous solutions.
Main Results:
- Molecular conformation significantly impacts the stability of D-mannitol polymorphs in the solid state.
- In unsaturated solutions, D-mannitol exists primarily as monomers; dimers emerge upon increasing concentration and in supersaturated solutions.
- The specific form of D-mannitol dimers (I-dimers, T-dimers, H-type dimers) correlates with the nucleation of delta, alpha, and beta polymorphs, respectively.
Conclusions:
- D-mannitol dimer formation and structure in supersaturated solutions are key factors influencing polymorphic nucleation.
- I-dimers favor delta-D-mannitol, T-dimers favor alpha-D-mannitol, and H-type dimers favor beta-D-mannitol formation.
- Molecular dynamics simulations provide a powerful tool for elucidating the microscopic origins of D-mannitol polymorphism.
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