An electrochiroptical molecular switch: mechanistic and kinetic studies

Area of Science:

• Coordination Chemistry
• Electrochemistry
• Spectroscopy

Background:

• Previous work reported synthesis of Cu(I/II) complexes with N,N-bis(2-quinilylmethyl)-(l)-methionine.
• Chemically oxidized and reduced forms exhibit mirror image circular dichroism (CD) spectra due to coordination sphere reorganization.
• Reorganization involves sulfur-oxygen exchange and ligand conformational changes during redox transitions.

Purpose of the Study:

• To demonstrate electrochemical triggering of redox-induced ligand reorganization in Cu(I/II) complexes.
• To elucidate the electrochemical and stereochemical details of this reorganization process.

Main Methods:

• CD spectroelectrochemistry
• Cyclic voltammetry with curve fitting
• CD titration
• Scanning electrochemical microscopy (SECM)
• Independent synthesis of chemical intermediates

Main Results:

• Electrochemical means successfully trigger ligand reorganization.
• A square-type mechanism describes the redox-induced process: reduction followed by reorganization, then oxidation and another reorganization.
• SECM identified a millisecond timescale for a key conformational conversion step.

Conclusions:

• The Cu(I/II) complex exhibits redox-switchable ligand reorganization.
• Electrochemical control allows for manipulation of the complex's coordination sphere and conformation.
• The study provides insights into the dynamics of metallointercalator complexes.