Crystal Structure of a Highly Efficient Clarifying Agent for Isotactic Polypropylene

Autor:	Stefan Steuernagel, Hans-Werner Schmidt, Roman Kress, Johannes J. Wittmann, Marko Schmidt, Jürgen Senker, Denis Schneider
Rok vydání:	2012
Předmět:	Crystallography Rietveld refinement Chemistry Tacticity Space group General Materials Science Orthorhombic crystal system General Chemistry Crystal structure Nuclear magnetic resonance spectroscopy Condensed Matter Physics Powder diffraction Magnetic dipole–dipole interaction
Zdroj:	Crystal Growth & Design. 12:2543-2551
ISSN:	1528-7505 1528-7483
DOI:	10.1021/cg300151s
Popis:	Using a combined approach based on X-ray powder diffraction and solid-state NMR spectroscopy, we were able to determine the crystal structure of 1,3,5-tris(2,2-dimethylpropionylamino)benzene, an efficient clarifying agent for isotactic polypropylene. The XPRD data and 1D solid-state NMR experiments allowed to exclude most of the possible primitive orthorhombic space groups with the exception of 11. The structure solution was carried out using real space methods including a close-contact penalty. Four space groups lead to reasonable wRp values below 10%. 13C13C double quantum (DQ) experiments of the labeled carbonyl group were measured with a supercycled symmetry based dipolar recoupling sequence. Taking into account the wRp values after Rietveld refinement as well as simulations of DQ build-up curves based on nine spin systems, the space group P212121 is clearly favored. The largest dipolar coupling within these spin systems was about 60 Hz corresponding to a distance of 5 A. 1,3,5-Tris(2,2-dimethylpropio...
Databáze:	OpenAIRE
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