STRUCTURE OF PHENOLIC ISOMERS OF 2-NITROFLUORANTHENE AND 3-NITROFLUORANTHENE STUDIED BY ONE-DIMENSIONAL AND 2-DIMENSIONAL H-1-NMR SPECTROSCOPY - COMPARATIVE-ANALYSIS OF MUTAGENICITY

The structures of selected phenolic metabolites of 2- and 3-nitrofluor anthene have been analyzed. H-1 NMR spectral analysis at 500 MHz using one- and two-dimensional methods proves that the site of hydroxy subs titution in two metabolites previously reported as 3-nitrofluoranthen- 8-ol and 3-nitrofluoranthen-9-ol had been reversed. A third and previo usly unidentified metabolite is shown to be 3-nitrofluoranthen-7-ol. C omplete analyis of NMR spectral data on 2- and 3-nitrofluoranthene ena bled confirmation of the previously reported structures of 2-nitrofluo ranthen-8-ol and 2-nitrofluoranthen-9-ol from derived chemical shift s ubstituent effects. Chemical shift data suggest that the nitro group i s not strictly coplanar with the aromatic ring system in solution and that metabolism at a distant site can alter the conformation about the C-N bond of the nitro group. Reported mutagenicity data are analyzed relative to imine quinone formation, chemical shift substituent effect s, electronegativity effects, and conformation in an attempt to explai n the large differences in mutagenicity between the C8 and C9 hydroxy isomers of 2- and 3-nitrofluoranthene.