The calculation of 1H, 13C, 14N isotropic and anisotropic hyperfine interactions for the 3-methyl indole cation and neutral radicals using hybrid density functional methods: models for in vivo tryptophan-based radicals

Density functional methods are used to calculate the isotropic and anisotropic hyperfine interactions for the 3-methyl indole cation and neutral free radicals. Calculated couplings are compared with experimental determinations for in vivo tryptophan-based radicals. The cation and anion radicals can be principally distinguished by the hyperfine couplings of the C2, C3 and N1 atoms and their associated protons. Increased conjugation between atoms C2 and C3, in the cation radical, is the principal reason for the differences is hyperfine couplings observed.