Publication

Abstract : Metalloporphyrins immobilised on solid polymer supports are developed as efficient model systems for catalyse enzyme, which dismutate hydrogen peroxide in many living organisms, saving them from several harmful oxidative processes. The metalloporphyrins employed are Mn(III), Fe(III) and Co(III) derivatives of anionic tetrasulphonated tetraphenylporphyrins (H2TPPS). The polymer support used was divinylbenzene crosslinked polystyrene (in bead form) which was first surface functionalised to chloromethyl derivative and then to N-alkyl pyridinium derivatives (PS). The negatively charged MTPPS were then appended on to the polymer support by ion exchange method. The catalytic efficiency of these immobilised MTPPS was found to be far superior to other supported systems reported earlier. The relative efficiency of the three supported metalloporphyrin systems was studied and compared in varying pH and temperature conditions. In acidic pH, the order of efficiency of the metalloderivatives was Fe(III) gt; Mn(III) gt; Co(III) while in basic pH, the order changed to Mn(III) K Co(III) gt; Fe(III). The maximum efficiency was found to be around pH 10-0 in all the cases. While the Fe(III) derivatives showed greater sensitivity to temperature, the Mn(III), on the contrary, showed the least sensitivity. The catalytic efficiency of the immobilised systems was found to be retained even after repeated use of the catalysts indicating a high degree of recyclability. © Indian Academy of Sciences.