Density functional studies of phenoxyl–Na+ ion complexes: implications for tyrosyl free radical interactions in vitro

Phenoxyl free radicals are examined for the effects of ion complexation on the 7a vibrational mode. Experimental FTIR data are compared with density functional calculations. It is shown that both the frequency and mode form are best reproduced by the ion complex models. The data suggest that phenoxyl and the related tyrosyl free radical exist as ion complexes in vitro.