Structural Features, Phase Relationships and Transformation Behavior of the Polymorphs I−VI of Phenobarbital

Autor:	Volker Kahlenberg, Thomas Gelbrich, Ulrich J. Griesser, Robin K. Harris, Neslihan Zencirci, David C. Apperley
Rok vydání:	2009
Předmět:	Infrared Chemistry Stereochemistry General Chemistry Calorimetry Nuclear magnetic resonance spectroscopy Condensed Matter Physics Drug compound symbols.namesake Crystallography symbols General Materials Science Chemical stability Raman spectroscopy Thermal analysis
Zdroj:	Crystal Growth & Design. 10:302-313
ISSN:	1528-7505 1528-7483
DOI:	10.1021/cg901062n
Popis:	Six of the more easily accessible forms of phenobarbital (Pbtl-I, II, III, IV, V, VI) were characterized by a variety of analytical methods (thermal analysis, solution calorimetry, X-ray diffraction methods, infrared, Raman and solid-state NMR spectroscopy), in order to get a clear picture of this complex polymorphic system and to eliminate severe inconsistencies in the existing data. On the basis of the thermochemical data and stability studies, we were able to clarify the thermodynamic relationships of the six forms with the aid of a semi-schematic energy/temperature diagram. The order of the thermodynamic stability at 20 °C was established as I > II > III > IV > V/VI, but forms I and II are energetically almost indistinguishable. This study provides a comprehensive description about the production, identification, and transformation pathways of the six polymorphs and discusses the structural origins for some of the unique solid-state phenomena of this important drug compound.
Databáze:	OpenAIRE
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