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Inne
Structural identification of paramagnetic iron porphyrins from Colorado coal with use of 1D and 2D 1H NMR spectroscopy: geochemical implications on their origin from heme.
Autorzy
Rok wydania
1994
Czasopismo
Numer woluminu
21
Strony
1059-1068
DOI
10.1016/0146-6380(94)90069-8
Kolekcja
Język
Angielski
Typ publikacji
Artykuł
A fraction of iron porphyrins from Colorado coal constituting one major and one minor C28 isomer was analysed with the use of 1D and 2D 1H nuclear magnetic resonance spectroscopy. 2D 1H COSY and NOESY experiments in a low viscosity solvent (CD3 OD) led to the structrural identification of the major component. Assignment of the hyperfine shifted resonances, of all the peripheral substituents on the porphyrin macrocycle, resulted in an unambiguous identification of iron(III) 2,7,12,18-tetramethyl-13,17-diethyl porphyrin. Reliability of the 2D 1H NMR method used was confirmed by analyzing a related structure, i.e. deuteroheme-IX in the same way. The minor constituent of the analysed fraction was identified by reproducing the 1H NMR spectrum with its synthetic counterpart: low-spin iron(III) 2,7,12,18-tetramethyl-3,8-diethyl porphyrin. Both identified coal iron porphyrins represent products derived from a common protoheme-IX related precursor, selectively degraded via different routes during coal diagenesis.