Heteroleptic Ligation by an endo-Functionalized Cage

Area of Science:

• Coordination Chemistry
• Supramolecular Chemistry
• Bioinorganic Chemistry

Background:

• Enzymatic active sites inspire the design of synthetic mimics.
• Non-heme iron oxygenases play crucial roles in biological oxidation reactions.
• Dynamic combinatorial chemistry offers a route to complex ligand architectures.

Purpose of the Study:

• To present a conceptual approach for quasi-heteroleptic complexes using endo-functionalized cage ligands.
• To synthesize and characterize a novel covalent organic cage ligand.
• To develop a functional model for non-heme iron oxygenases.

Main Methods:

• Dynamic combinatorial chemistry for cage ligand synthesis.
• X-ray crystallography for solid-state structure determination.
• Spectroscopic and analytical methods for solution characterization.
• Biomimetic reactivity studies with dioxygen and α-ketoglutarate.

Main Results:

• A covalent organic cage ligand with carboxylate and imidazole coordinating units was synthesized.
• The iron(II) complex (Fe@2) exhibits a five-coordinate metal center, avoiding dimerization.
• Fe@2 serves as a detailed structural model for non-heme iron oxygenases.
• Implementation of α-ketoglutarate and observation of biomimetic dioxygen reactions.

Conclusions:

• The developed cage ligand enables the synthesis of unique quasi-heteroleptic complexes.
• Fe@2 represents an unprecedented structural model for non-heme iron oxygenases.
• The biomimetic reactivity of Fe@2 opens avenues for functional studies in bioinorganic chemistry.