Redox-Responsive Dimerization in a Ferrocene-Ureidopyrimidone Supramolecular Assembly.

Area of Science:

• Supramolecular Chemistry
• Electrochemistry
• Organic Chemistry

Background:

• Ureidopyrimidones (UPy) are known for strong hydrogen-bonded dimerization in solution.
• Few studies explore UPy derivatives with redox-active groups and their impact on dimerization.
• Controlling supramolecular assembly through redox stimuli is an emerging area.

Purpose of the Study:

• To investigate the electrochemical behavior of a ferrocene-functionalized ureidopyrimidone (UPy(Fc)).
• To demonstrate redox-controlled dimerization and dissociation in the UPy system.
• To quantify the effect of redox state on UPy dimerization constants.

Main Methods:

• Electrochemical investigation using cyclic voltammetry (CV).
• ¹H NMR spectroscopy to confirm dimerization state.
• Analysis of scan rate and concentration dependence of CVs.
• Measurement of diffusion coefficients.
• CV data simulation to determine dissociation constants (K_dis).

Main Results:

• UPy(Fc) exhibits reversible redox behavior.
• Reduced UPy(Fc) exists as a fully formed dimer in CH₂Cl₂.
• Oxidation to ferrocenium converts the dimer to a species favoring monomer formation.
• Reduction regenerates the dimer in a chemically reversible manner.
• Dissociation constants (K_dis) were determined: 2.1 × 10^-6 M (reduced) and 12 M (oxidized).

Conclusions:

• Strong and reversible redox-control of UPy dimerization is achievable.
• Oxidation likely disrupts dimerization via electrostatic repulsion and reduced H-bonding.
• This work opens avenues for redox-switchable supramolecular systems.