Enzyme Control Over Ferric Iron Magnetostructural Properties

Fe3+ complexes in aqueous solution can exist as discrete mononuclear species or multinuclear magnetically coupled species. Stimuli-driven change to Fe3+ speciation represents a powerful mechanistic basis for magnetic resonance sensor technology, but ligand design strategies to exert precision control of aqueous Fe3+ magnetostructural properties are entirely underexplored. In pursuit of this objective, we rationally designed a ligand to strongly favor a dinuclear mu-oxo-bridged and antiferromagnetically coupled complex, but which undergoes carboxylesterase mediated transformation to a mononuclear high-spin Fe3+ chelate resulting in substantial T-1-relaxivity increase. The data communicated demonstrate proof of concept for a novel and effective strategy to exert biochemical control over aqueous Fe3+ magnetic, structural, and relaxometric properties.

Automated summary

This study presents a novel strategy for biochemical control over Fe3+ ions, demonstrating precise manipulation of Fe3+ complex properties through ligand design. By mediating the transformation through carboxylesterase, a substantial increase in Fe3+ high-spin relaxivity was achieved, indicating a potential advancement in aqueous Fe3+ magnetic resonance sensor technology.