AbstractA new 5‐O‐membered crown ether spin‐labelled with a triphenylmethyl group was prepared. The intramolecular unpaired π‐electron delocalization was investigated by ENDOR. The ENDOR of the crown methylene group adjacent to the aromatic ring revealed non‐equivalence in the magnitude of the proton hyperfine splittings. Based on the temperature‐dependent ENDOR line separation, the activation energy of the conformational change of the methylene protons was estimated. Upon metal chelation into the crown ring the dissociation of the dimer to the monomer radical was greatly affected, and an increase in the activation energy of the vibrating methylene protons was detected.
Conformational analysis of benzo-15-crown-5 and 2,3-(4?-benzoyl)benzo-15-crown-5
作者:O. A. Raevskii、V. V. Tkachev、V. P. Kazachenko、A. N. Razdol'skii、I. I. Bulgak、V. E. Zubareva
DOI:10.1007/bf00953285
日期:1989.4
CHEN ZHENDONG; YUAN RUNXIAN; WANG TIANYI, ORG. CHEM.,(1987) N 1, 29-34