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Complete assignment of the carbon‐13 NMR spectrum of chlorophyl a
Author(s) -
Lötjönen Simo,
Hynninen Paavo H.
Publication year - 1981
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270160410
Subject(s) - delocalized electron , chemistry , carbon fibers , photosynthesis , monomer , carbon 13 nmr , photochemistry , stereochemistry , organic chemistry , materials science , polymer , biochemistry , composite number , composite material
The 13 C NMR spectrum (at natural abundance) of monomeric chlorophyll α in acetone‐ d 6 has been recorded to re‐examine the assignments of the low field (aromatic‐olefinic) region of the spectrum. The assignments, made by the examination of the fully coupled spectrum and by the use of long‐range selective 1 H decoupling (LSPD) with low‐power irradiation, were compared with those of the previous reports. The results of the present work clarify the ambiguities previously encountered in the assignment of the 10a‐ester, 7c‐propionyl, P‐2‐phytyl, 2b‐vinyl, γ‐ and β‐methine carbon atoms, as well as the β‐pyrrolic carbon‐6 and α‐pyrrolic carbons −16 and −17 of chlorophyll α. Reassignment of the three last carbons was found necessary. Knowledge of the chemical shifts of these carbon atoms was considered to be particularly valuable, as it yields relevant information on the delocalized π electron system which is crucial for the function of chlorophyll in photosynthesis.