Peroxidase Mechanism of Fe(III) Tetrakis(4-Sulphonatophenyl)Porphyrin Encapsulated within HKUST-1, a Prototypical Metal Organic Framework

Abdulaziz A. Alanazi,¹ Randy W Larsen¹.

Department of Chemistry, University of South Florida, 4202 East Fowler Avenue, Tampa, Florida 33620, United States.

In order to carry out essential life processes nature has had to evolve heme enzymes capable of synthesizing and manipulating complex molecules. These proteins perform a plethora of chemical reactions utilizing a single iron porphyrin active site embedded within an evolutionarily designed protein pocket. The first class of metal-organic materials (MOMs) that mimic heme enzymes in terms of both structure and reactivity are based upon a prototypal MOM, HKUST-1, into which catalytically active metalloporphyrins are selectively encapsulated. The MOMzyme-1 class could therefore represent a new paradigm for heme biomimetic catalysis since it combines the activity of a homogeneous catalyst with the stability and recyclability of heterogeneous catalytic systems within a single material. It has been previously determined that Fe(III)4SP@HKUST-1 (MOMzyme-1) displays peroxidase activity by utilizing 2,2' azinobis(3-ethylbenzthiazoline)- 6-sulfonate (ABTS) as organic substrate and Hydrogen peroxide (H₂O₂). Here the peroxidase kinetic mechanism of Fe(III)4SP@HKUST-1 is examined in detail by probing the reaction rate as a function of H2O2, ABTS and pH. The results are compared with Fe4SP in solution as well as the heme protein myoglobin.