ANILINE DERIVATIVES AS ENHANCERS AND INHIBITORS OF THE LUMINOL-H2O2-HORSERADISH PEROXIDASE CHEMILUMINESCENCE - EFFECTS OF THE HAMMETT CONSTANTS OF THE SUBSTITUENTS

The effects of monosubstituted anilines an the luminol-H2O2-horseradis h peroxidase chemiluminescence were related with the type of substitue nt and position. Anilines substituted in meta- and para-positions by s ubstituents with Hammett constants (sigma) lesser than -0.27 produced an inhibition of the chemiluminescence. On the contrary, those aniline s with substituents with Hammett constants between -0.27 and +0.18 pro duced an enhancer effect. Anilines with substituents with Hammett cons tants greater than +0.18 produced a slight enhancement or inhibition. An alike evolution was observed in ortho-substituted anilines. These e ffects were related with the reduction potentials of aniline radicals and the reaction rates of these anilines with the compounds of horsera dish peroxidase. The data obtained permitted the prediction of the inh ibitor or enhancer character of the aniline derivatives, and even the power of enhancement. (C) 1998 Elsevier Science S.A.