Molecular motion in crown ethers. Application of 13C and 2H NMR to the study of 4-carboxybenzo-24-crown-8 ether and its KNCS complex in solution and in the solid phase

Autor:	G. W. Buchanan, C.I. Ratcliffe, A. Moghimi
Rok vydání:	1996
Předmět:	Crystallography chemistry.chemical_compound Chemistry Phase (matter) Organic Chemistry Crown (botany) Molecular motion Organic chemistry Ether General Chemistry Ring (chemistry) Catalysis
Zdroj:	Canadian Journal of Chemistry. 74:1437-1446
ISSN:	1480-3291 0008-4042
DOI:	10.1139/v96-161
Popis:	Large-amplitude solid phase molecular motion has been detected in the macrocyclic ring of the title crown either via 13C CPMAS NMR. To study the details of the dynamic processes, two selectively deuterated d4 derivatives have been prepared and examined via 2H NMR as a function of temperature. A phase change occurring around 277 K has been verified by differential scanning calorimetry (DSC) and a model for the motional processes has been developed involving equivalent two-site flips of the CD2 groups. The amplitude of the CD2 motions apparently decreases the closer the group is to the aromatic ring. The influence of KNCS complexation on the 13C CPMAS spectrum and on 13C spin lattice relaxation times in solution has been explored. Key words: macrocyclic ethers, solid phase dynamics.
Databáze:	OpenAIRE
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