A guide to secondary coordination sphere editing.

Area of Science:

• Coordination Chemistry
• Biomimetic Chemistry
• Catalysis

Background:

• Metalloenzymes employ secondary coordination spheres (SCSs) to modulate substrate reactivity, facilitate small molecule transport, and tune redox potentials, thereby enhancing catalytic function.
• In biomimetic chemistry, the strategic integration of SCS residues (e.g., Brønsted/Lewis acids/bases, crown ethers, redox-active groups) is vital for achieving desired functionalities.

Purpose of the Study:

• To review recent (2015-2021) developments in ligand construction specifically for secondary coordination spheres (SCSs).
• To highlight how advances in synthetic chemistry facilitate the creation of sophisticated SCSs for catalytic applications.

Main Methods:

• Review of recent literature focusing on ligand synthesis and its application in constructing SCSs.
• Analysis of how designed SCSs influence the activity and selectivity of catalytic transformations.

Main Results:

• Demonstration of how fundamental organic and inorganic synthesis strategies are applied to build complex SCSs.
• Showcasing the successful application of SCS-modified catalysts in key transformations for clean fuel generation, such as small molecule reduction (H+, N2, CO2, NO, O2).

Conclusions:

• Ligand design for SCSs is a powerful strategy for advancing both metalloenzyme understanding and biomimetic catalysis.
• Cooperative effects between metal centers and ligands within SCSs are essential for efficient substrate activation and catalysis, particularly in clean energy relevant reactions.