P-PHENOL DERIVATIVES AS ENHANCERS OF THE CHEMILUMINESCENT LUMINOL-HORSERADISH PEROXIDASE-H2O2 REACTION - SUBSTITUENT EFFECTS

We studied the substituent effects of ten p-phenol derivatives and aniline on the chemiluminescence from the luminol-horseradish peroxidase-H2O2 system. The enhancer effects of some compounds (phenol, p-cresol, p-coumaric acid, p-hydroxybenzoic acid, p-hydroxymethylbenzoate, p-hydro xybenzaldehyde and aniline) were studied against pH and concentration. These compounds enhanced the chemiluminescent emission of luminol between 2 and 40 times. Phenols with activative substituents (in the para-position) of the benzene ring and phenol, produced a greater increase (at low concentration) in the chemiluminescence than those with deactivating substituents. Phenols with very active or very deactivating substituents of the benzene ring decreased the chemiluminescence of luminol. We found certain relations between the pKa values and the reducing character of these phenol derivatives with their enhancer or inhibition effects on the luminol chemiluminescence.