Design of More Powerful Iron-TAML Peroxidase Enzyme Mimics

Environmentally useful, small molecule mimics of the peroxidase enzymes must exhibit very high reactivity in water near neutral pH. Here we describe the design and structural and kinetic characterization of a second generation of iron(III)-TAML activators with unprecedented peroxidase-mimicking abilities. Iterative design has been used to remove the fluorine that led to the best performers in first-generation iron-TAMLs. The result is a superior catalyst that meets a green chemistry objective by being comprised exclusively of biochemically common elements. The rate constants for bleaching at pH 7, 9, and 11 of the model substrate, Orange 11, shows that the new Fe-III-TAML has the fastest reactivity at pH's closer to neutral of any TAML activator to date. Under appropriate conditions, the new catalyst can decolorize Orange 11 without loss of activity for at least 10 half-lives, attesting to its exceptional properties as an oxidizing enzyme mimic.