Gated electron transfers at synthetic iron-sulfur cubanes
Liam Grunwald, Mariko Inoue, Paula Cendoya Carril, Michael Wörle, Victor Mougel
Abstract
Electron transfers, abundantly mediated by cubane-type iron-sulfur clusters (Fe 4 S 4 ), play a central role in the metabolic processes of all living organisms. The most challenging electron transfers, requiring the strongest reducing power, are believed to be gated ones, which cause the associated cofactors to operate at varying redox potentials ( E ). However, Fe 4 S 4 's E values are commonly described as static parameters, preventing the full understanding of their redox properties. By investigating the intricacies of the alkali-ion-assisted electron transfer mechanism in [Fe 4 S 4 (DmpS) 4 ] n− and [Fe 4 S 4 (PhS) 4 ] n− (2,6-dimesitylphenyl [Dmp]; phenyl [Ph]), we establish here an approach to Fe 4 S 4 (SR) 4 complexes, in which the chemical environment dictates the cluster's E . The investigated systems exhibit dynamically modular potentials, whose ranges supersede and cover those accessible by all Fe 4 S 4 -containing enzymes. We show that alkali-ion-[Fe 4 S 4 (SR) 4 ] assemblies store electrical energy that can be liberated on demand. This is exploited to drive a formerly "uphill" electron transfer, highlighting the relevance of these systems as functional models for archerases.