Aromatic foldamers as scaffolds for metal second coordination sphere design

Area of Science:

• Bioinorganic Chemistry
• Supramolecular Chemistry
• Synthetic Chemistry

Background:

• The function of metalloproteins is dictated by both the first and second coordination spheres of metal centers.
• Synthetically controlling the second coordination sphere of metal complexes is crucial but challenging.
• Bioinspired artificial architectures offer a promising route to engineer these environments.

Purpose of the Study:

• To develop a novel method for creating tailored second coordination spheres around synthetic metal complexes.
• To utilize aromatic oligoamide foldamers to construct a rigid, modular, and well-defined environment.
• To investigate the impact of this engineered environment on a tethered [2Fe-2S] cluster.

Main Methods:

• Synthesis of aza-aromatic monomers functionalized with a [2Fe-2S] cluster.
• Incorporation of these monomers into conical helical foldamer sequences.
• Characterization using X-ray crystallography, Nuclear Magnetic Resonance (NMR), and Infrared (IR) spectroscopy.

Main Results:

• A conical foldamer architecture was successfully designed to confine the metal complex.
• The aromatic oligoamide backbone influenced the structure of the [2Fe-2S] cluster.
• The foldamer environment was shown to alter the fluxional processes of the metal cluster, despite no direct designed interactions.

Conclusions:

• Aromatic oligoamide foldamers provide a modular and predictable platform for constructing artificial second coordination spheres.
• This approach enables the engineering of confined environments that modulate the properties of metallo-organic complexes.
• The study demonstrates the potential of bioinspired foldamers in controlling metal center chemistry and dynamics.