A Redox-Switchable, Allosteric Coordination Complex

A redox-regulated
molecular tweezer complex was synthesized via
the weak-link approach. The PtII complex features a redox-switchable
hemilabile ligand (RHL) functionalized with a ferrocenyl moiety, whose
oxidation state modulates the opening of a specific coordination site.
Allosteric regulation by redox agents gives reversible access to two
distinct structural statesa fully closed state and a semi-open
statewhose interconversion was studied via multinuclear NMR
spectroscopy, cyclic voltammetry, and UV–vis–NIR spectroscopy.
Two structures in this four-state system were further characterized
via SCXRD, while the others were modeled through DFT calculations.
This fully reversible, RHL-based system defines an unusual level of
electrochemical control over the occupancy of a specific coordination
site, thereby providing access to four distinct coordination states
within a single system, each defined and differentiated by structure
and oxidation state.