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Inhibiting Sublimation of Thymol by Cocrystallization
Hui Zu1, Rodger F Henry2, Geoff G Z Zhang2
1School of Pharmacy, University of Iowa, Iowa City, IA 52242, USA.
Journal of Pharmaceutical Sciences
|October 24, 2022
Summary
This study shows that forming a thymol:4,4'-dipyridyl cocrystal (Form I) significantly reduces thymol
Area of Science:
- Solid-state chemistry
- Materials science
- Crystallography
Background:
- Thymol is known to sublime, leading to odor issues.
- Controlling solid sublimation is crucial for material stability and odor masking.
Purpose of the Study:
- To investigate the cocrystallization of thymol with 4,4 -dipyridyl to suppress thymol sublimation.
- To characterize the resulting cocrystal forms and their impact on sublimation rates.
Main Methods:
- Solution-mediated phase transformation for cocrystal preparation.
- Solid-state and vapor phase transformations for polymorph formation.
- Gravimetry analysis to quantify sublimation rates.
Main Results:
- A thymol:4,4 -dipyridyl (2:1) cocrystal (Form I) was successfully prepared.
- Cocrystal Form I formation involves O-H (phenol) ··· N (pyridyl) hydrogen bonds.
- Cocrystal Form I reduced the sublimation rate of thymol by 38-fold.
- A cocrystal polymorph (Form II) was obtained via solid-state or vapor phase transformation upon heating.
Conclusions:
- Cocrystallization is an effective strategy to reduce the vapor pressure and sublimation of solids.
- This approach can be utilized for odor-masking applications by suppressing volatile compound release.
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