NMR spectra of the porphyrins. 38 —Conformational analysis of azacycloheptane and azacyclooctane using a novel cobalt(III) porphyrin shift reagent | Zendy

Abraham Raymond J. | Zendy; Medforth Craig J. | Zendy

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NMR spectra of the porphyrins. 38 —Conformational analysis of azacycloheptane and azacyclooctane using a novel cobalt(III) porphyrin shift reagent

Author(s) -

Abraham Raymond J.,

Medforth Craig J.

Publication year - 1990

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/mrc.1260280412

Subject(s) - chemistry , porphyrin , tetraphenylporphyrin , ring (chemistry) , cobalt , reagent , proton nmr , nmr spectra database , nuclear magnetic resonance spectroscopy , crystallography , spectral line , stereochemistry , computational chemistry , photochemistry , organic chemistry , physics , astronomy

A novel NMR shift reagent, cobalt(III) meso ‐tetraphenylporphyrin (CoTPP) was used to determine the conformations of azacycloheptane and azacyclooctane ligands complexed to the metalloporphyrin. Using the observed ring current shifts and a previously calibrated ring current model, the best agreement between the observed and calculated ring current shifts for azacycloheptane was obtained for a chair conformation, in agreement with previous theoretical and experimental studies on the conformational stability of seven‐membered rings. The ring current shifts for azacyclooctane are best interpreted in terms of a mixture of many conformations. These results suggest that CoTPP may be useful as a probe of other conformationally mobile ligands.

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