Solid-state formation of centrosymmetric cage dimeric 4-aryl-1,4-dihydropyridines via non-symmetric syn-dimers studied by 13C cross-polarization magic angle spinning NMR spectroscopy
✍ Scribed by Andreas Hilgeroth; Günter Hempel; Ute Baumeister; Detlef Reichert
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 132 KB
- Volume
- 37
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
The solid-state formation of a centrosymmetric cage dimeric 4-aryl-1,4-dihydropyridine was monitored by 13 C cross polarization magic angle spinning (CP/MAS) NMR spectroscopy. The spectra of the photodimerizing derivatives document the changes in symmetry during the reaction and the reaction progress. Furthermore, they clearly reflect characterizing conformational properties of the molecules. Starting from centrosymmetric pairs of monomeric molecules, dimerization proceeds to non-symmetrical syn-dimers, that subsequently cyclize to centrosymmetric cage dimers. Thus the application of 13 C CP/MAS NMR spectroscopy proves an unusual symmetry breaking in solid-state photodimerization.