Carbon-13 and proton EPR analysis of the benzo[a]pyrene cation

The molecular etiology and prevention of estrogen-initiated cancers

“…Experimental data indicate that the spin density in the high occupied molecular orbitals of BP +. , which follows the same pattern as the charge density, is greater at C-6, followed by C-1 and C-3 (Sullivan et al, 1985). These experiments are corroborated by molecular orbital calculations in BP (Loew, et al, 1978; Shipman, 1978) and BP +.…”

Free Radicals of Benzo(a)pyrene and Derivatives

“…Further information is also available from simulations of some of the spectra ofthe dimethyl-BaP's. Thus, examination of the spectra of 4,5-dimethyl-BaP (49) (50), the proton splitting in the 1-position is assigned as the second-largest proton splitting, in spite of the fact that the 1-methyl splitting is only the fifthlargest methyl splitting. The other splittings have been assigned in the same relative order and are as shown in Table 2.…”

“…The EPR spectrum of the BaP cation radical in H2SO4 was first observed 25 years ago (2) and has since been investigated by several groups (3-5), but only recently has a complete analysis been proposed (29,49,50). The interpretation of the BaP cation radical EPR spectrum was made difficult due to the asymmetry of the molecule which indicates that all 12 protons should be nonequivalent, leading to a maximum possible 212 (4096) lines in the EPR spectrum.…”

“…The 13C splitting constants can be obtained by simply measuring the increase in the total width of the EPR spectrum of the 13C derivative over that of the protonated derivative (50). Figure 3 shows that under low resolution conditions it is relatively easy to unambiguously locate the outermost lines of the spectra and hence measure the total width.…”

Free radicals of benzo(a)pyrene and derivatives.

“…The EPR spectrum of the BaP cation radical in H2SO4 was first observed 25 years ago (2) and has since been investigated by several groups (3)(4)(5), but only recently has a complete analysis been proposed (29,49,50). The interpretation of the BaP cation radical EPR spectrum was made difficult due to the asymmetry of the molecule which indicates that all 12 protons should be nonequivalent, leading to a maximum possible 212 (4096) lines in the EPR spectrum.…”