Correlation of the crystal structure and solid-state13C NMR spectrum of pyromellitic dianhydride

Autor:	Frank J. Dinan, Willis T. Schwartz, Roger A. Wolfe
Rok vydání:	1991
Předmět:	Pyromellitic dianhydride Stereochemistry Solid-state General Chemistry Nuclear magnetic resonance spectroscopy Crystal structure Carbon-13 NMR Bond length chemistry.chemical_compound Crystallography Differential scanning calorimetry chemistry Melting point General Materials Science
Zdroj:	Magnetic Resonance in Chemistry. 29:440-443
ISSN:	1097-458X 0749-1581
DOI:	10.1002/mrc.1260290506
Popis:	The interatomic distances for crystalline pyromellitic dianhydride (PMDA) were calculated from x-ray crystallographic data. The CP-MAS 13C NMR spectrum of PMDA was found to be consistent with and accountable for in terms of these distances after literature assignment errors were corrected. An anomalous peak was observed in the differential scanning calorimetry thermogram of PMDA. The entropy change associated with this transition indicates that a two-fold change in symmetry occurs approximately 60°C below the melting point of PMDA. Attempts to observe this transition by CP-MAS 13C NMR were unsuccessful.
Databáze:	OpenAIRE
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