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Solid‐state formation of centrosymmetric cage dimeric 4‐aryl‐1,4‐dihydropyridines via non‐symmetric syn ‐dimers studied by 13 C cross‐polarization magic angle spinning NMR spectroscopy
Author(s) -
Hilgeroth Andreas,
Hempel Günter,
Baumeister Ute,
Reichert Detlef
Publication year - 1999
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/(sici)1097-458x(199905)37:5<376::aid-mrc458>3.0.co;2-o
Subject(s) - chemistry , aryl , nuclear magnetic resonance spectroscopy , crystallography , magic angle spinning , molecule , spectroscopy , monomer , magic angle , solid state nuclear magnetic resonance , carbon 13 nmr , stereochemistry , photochemistry , nuclear magnetic resonance , organic chemistry , polymer , alkyl , physics , quantum mechanics
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. Copyright © 1999 Society of Chemical Industry