Thermo-Structural Characterization of Phase Transitions in Amorphous Griseofulvin: From Sub-Tg Relaxation and Crystal Growth to High-Temperature Decomposition

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216275%3A25310%2F24%3A39922017" target="_blank" >RIV/00216275:25310/24:39922017 - isvavai.cz</a>

Result on the web

<a href="https://www.mdpi.com/1420-3049/29/7/1516" target="_blank" >https://www.mdpi.com/1420-3049/29/7/1516</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.3390/molecules29071516" target="_blank" >10.3390/molecules29071516</a>

Result language

angličtina

Original language name

Thermo-Structural Characterization of Phase Transitions in Amorphous Griseofulvin: From Sub-Tg Relaxation and Crystal Growth to High-Temperature Decomposition

Original language description

The processes of structural relaxation, crystal growth, and thermal decomposition were studied for amorphous griseofulvin (GSF) by means of thermo-analytical, microscopic, spectroscopic, and diffraction techniques. The activation energy of similar to 395 kJ center dot mol(-1) can be attributed to the structural relaxation motions described in terms of the Tool-Narayanaswamy-Moynihan model. Whereas the bulk amorphous GSF is very stable, the presence of mechanical defects and micro-cracks results in partial crystallization initiated by the transition from the glassy to the under-cooled liquid state (at similar to 80 degrees C). A key aspect of this crystal growth mode is the presence of a sufficiently nucleated vicinity of the disrupted amorphous phase; the crystal growth itself is a rate-determining step. The main macroscopic (calorimetrically observed) crystallization process occurs in amorphous GSF at 115-135 degrees C. In both cases, the common polymorph I is dominantly formed. Whereas the macroscopic crystallization of coarse GSF powder exhibits similar activation energy (similar to 235 kJ center dot mol(-1)) as that of microscopically observed growth in bulk material, the activation energy of the fine GSF powder macroscopic crystallization gradually changes (as temperature and/or heating rate increase) from the activation energy of microscopic surface growth (similar to 105 kJ center dot mol(-1)) to that observed for the growth in bulk GSF. The macroscopic crystal growth kinetics can be accurately described in terms of the complex mechanism, utilizing two independent autocatalytic Sestak-Berggren processes. Thermal decomposition of GSF proceeds identically in N-2 and in air atmospheres with the activation energy of similar to 105 kJ center dot mol(-1). The coincidence of the GSF melting temperature and the onset of decomposition (both at 200 degrees C) indicates that evaporation may initiate or compete with the decomposition process.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

10400 - Chemical sciences

Project

—

Continuities

S - Specificky vyzkum na vysokych skolach<br>I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2024

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Molecules

ISSN

1420-3049

e-ISSN

1420-3049

Volume of the periodical

29

Issue of the periodical within the volume

7

Country of publishing house

CH - SWITZERLAND

Number of pages

22

Pages from-to

1516

UT code for WoS article

001201510300001

EID of the result in the Scopus database

2-s2.0-85190092590