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Mechanochemically Induced Conversion of Crystalline Benzamide Polymorphs by Seeding
Franziska Fischer1,2, Sebastian Greiser1,2, Dietmar Pfeifer1
1BAM Federal Institute for Materials Research and Testing, Richard-Willstätter-Str. 11, 12489, Berlin, Germany.
Angewandte Chemie (International Ed. in English)
|November 5, 2016
Summary
Mechanochemical treatment enabled a complete transformation of benzamide form I into the metastable form III. Nicotinamide seeding facilitated this conversion, with molecules incorporating into the benzamide crystal lattice.
Area of Science:
- Solid-state chemistry
- Materials science
- Crystallography
Background:
- Benzamide exhibits polymorphism, with three known forms, complicating crystallization.
- Previously, only mixtures of stable form I and metastable forms were achievable.
Purpose of the Study:
- To achieve a complete transformation of benzamide form I into the metastable form III.
- To investigate the role of mechanochemical seeding using nicotinamide.
Main Methods:
- Mechanochemical treatment was employed for solid-state transformation.
- In situ powder X-ray diffraction monitored the transformation pathway.
- Nuclear Magnetic Resonance (NMR) spectroscopy analyzed crystal lattice incorporation.
Main Results:
- Complete conversion of benzamide form I to form III was achieved via mechanochemistry.
- Nicotinamide acted as a catalyst, enabling mechanochemical seeding.
- NMR confirmed statistical incorporation of nicotinamide into the benzamide form III lattice.
Conclusions:
- Mechanochemical treatment offers a viable route for complete polymorphic transformation.
- Nicotinamide seeding is an effective strategy for activating solid-state conversions.
- Understanding guest molecule incorporation is crucial for controlling polymorphic transitions.
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