Tuning the Apparent Stability of Polymorphic Cocrystals through Mechanochemistry

  • Mechanochemistry has become a valuable method for the synthesis of new materials and molecules, with a particular strength for screening and preparing multicomponent crystals. In this work, two novel cocrystals of pyrazinamide (PZA) with pimelic acid (PA) were prepared mechanochemically. Their formation was monitored in real time by in situ synchrotron powder X-ray diffraction. Control over the polymorphic form was obtained through the selective choice of liquid additive via liquid assisted grinding. Slurry experiments and dispersion-corrected density functional theory calculations suggest that Form I is the thermodynamically stable form under ambient conditions. Upon aging, Form II converts to Form I. The stability of Form II upon aging was found to depend strongly on the milling duration, intensity, and material of the milling vessels. Longer or higher energy milling drastically increased the lifetime of the Form II product. For the first time, this work also demonstrates that theMechanochemistry has become a valuable method for the synthesis of new materials and molecules, with a particular strength for screening and preparing multicomponent crystals. In this work, two novel cocrystals of pyrazinamide (PZA) with pimelic acid (PA) were prepared mechanochemically. Their formation was monitored in real time by in situ synchrotron powder X-ray diffraction. Control over the polymorphic form was obtained through the selective choice of liquid additive via liquid assisted grinding. Slurry experiments and dispersion-corrected density functional theory calculations suggest that Form I is the thermodynamically stable form under ambient conditions. Upon aging, Form II converts to Form I. The stability of Form II upon aging was found to depend strongly on the milling duration, intensity, and material of the milling vessels. Longer or higher energy milling drastically increased the lifetime of the Form II product. For the first time, this work also demonstrates that the choice of milling jar can have a decisive effect on the aging stability of a bulk polymorphic powder. In contrast to material prepared in steel milling vessels, the preparation of Form II in Perspex (PMMA) vessels increased its lifetime 3-fold. These findings offer a new dimension to garnering control over mechanochemical cocrystallization and demonstrate the critical importance of the careful and timely ex situ screening of ball mill grinding reactions. This will be of importance for potential industrial applications of mechanochemical cocrystallization where understanding polymorph longevity is crucial for the development of a robust preparative protocol.zeige mehrzeige weniger

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Autor*innen:Hannes Kulla, C. Becker, Adam MichalchukORCiD, Kevin Linberg, B. Paulus, Franziska EmmerlingORCiD
Dokumenttyp:Zeitschriftenartikel
Veröffentlichungsform:Verlagsliteratur
Sprache:Englisch
Titel des übergeordneten Werkes (Englisch):Crystal Growth & Design
Jahr der Erstveröffentlichung:2019
Organisationseinheit der BAM:6 Materialchemie
6 Materialchemie / 6.3 Strukturanalytik
Verlag:ACS Publications
Jahrgang/Band:19
Ausgabe/Heft:12
Erste Seite:7271
Letzte Seite:7279
DDC-Klassifikation:Naturwissenschaften und Mathematik / Chemie / Analytische Chemie
Freie Schlagwörter:Liquids; Materials; Organic compounds; Physical and chemical processes; Stability
Themenfelder/Aktivitätsfelder der BAM:Chemie und Prozesstechnik
DOI:10.1021/acs.cgd.9b01158
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:23.01.2020
Referierte Publikation:Ja
Datum der Eintragung als referierte Publikation:23.01.2020
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