THE CALCULATION OF H-1,C-13, N-14 ISOTROPIC AND ANISOTROPIC HYPERFINEINTERACTIONS 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 ani sotropic hyperfine interactions for the 3-methyl indole cation and neu tral free radicals. Calculated couplings are compared with experimenta l determinations for in vivo tryptophan-based radicals. The cation and anion radicals can be principally distinguished by the hyperfine coup lings of the C2, C3 and N1 atoms and their associated protons. Increas ed conjugation between atoms C2 and C3, in the cation radical, is the principal reason for the differences in hyperfine couplings observed.