Polyethylene glycol (PEG)-linked manganese halogenated porphyrins (Chart ) catalyzed oxidation of azo dyes (Chart ) by H2O2 under mild conditions such as pH 8.0 at 25 °C especially when imidazole was present, causing the decoloration of azo dyes. The decoloration of azo dyes by synthetic manganese porphyrins under mild conditions was first reported. The decoloration rate depended on the structures of the porphyrins, in which the largest rate was observed in the presence of PEG−MnDCPP. The decoloration may be contributed by radical species rather than electrophilic species, consistent with the side-chain oxidation of toluene. Kinetics on polyethylene glycol-linked manganese porphyrin-catalyzed decoloration of C.I. Acid Orange 7 by hydrogen peroxide revealed that the decoloration was contributed at the oxidation process by manganese porphyrins with hydrogen peroxide in the polymer domain rather than the complex-formation process between manganese porphyrins and azo dyes.

Manganese protoporphyrin or mesoporphyrin derivatives catalysed the decolorisation of azo dyes by hydrogen peroxide under mild conditions, pH 8.0 and 25°C. The decolorisation rate was increased by the presence of manganese protoporphyrin or mesoporphyrin derivatives and was dependent upon the structures of the porphyrins and of the azo dyes. The rate was found to depend upon the concentration of ligands. Kinetic studies of the decolorisation rate by hydrogen peroxide catalysed by a poly(ethylene glycol)‐linked manganese mesoporphyrin derivative showed how the structures of the porphyrin and the azo dye affect the rate.

The effect of manganese protoporphyrin, manganese halogenated porphyrins, polyethylene glycol (PEG)-linked manganese porphyrin and PEG-linked manganese halogenated porphyrins (Scheme 1), on the decoloration rates of C.I. Solvent Yellow 14 by m-chloroperbenzoic acid (mCPBA) at 25°C in non-aqueous solvent was examined. The decoloration rate of C.I. Solvent Yellow 14 by mCPBA was accelerated due to the presence of manganese porphyrin derivatives, depending on the structures of porphyrin derivatives. Interestingly, the decoloration rate decreased due to the presence of ligands such as imidazole, in comparison to the rate catalyzed by the manganese porphyrins in aqueous solution.

No abstract