Recyclable Homogeneous Catalysis Enabled by Dynamic Coordination on Rhodium(II) Axial Sites of Metal-Organic...

Area of Science:

• Catalysis
• Materials Science
• Nanotechnology

Background:

• Nanoparticle catalytic activity depends on surface chemistry, affecting stability and substrate diffusion.
• Metal-organic polyhedra (MOPs) offer tunable structures for catalytic applications.

Purpose of the Study:

• Investigate the impact of outer surface chemistry on Rh(II)-based MOPs (Rh-MOPs) in homogeneous catalysis.
• Develop methods for solubilizing and recovering Rh-MOP catalysts.

Main Methods:

• Post-synthetic coordination of aliphatic imidazole ligands to exohedral Rh(II) sites of Rh-MOPs.
• Solubilization of a cuboctahedral Rh-MOP in dichloromethane for homogeneous catalysis.
• Ligand exchange reactions for catalyst precipitation and recovery.

Main Results:

• Surface ligand coordination did not impede Rh-MOP catalytic activity in styrene aziridination and cyclopropanation.
• A dynamic Rh-imidazole coordination bond allows for maintained catalytic performance.
• A ligand-mediated precipitation approach enabled efficient recovery and reuse of the homogeneous Rh-MOP catalyst.

Conclusions:

• Outer surface chemistry of Rh-MOPs can be tailored to achieve homogeneous catalysis.
• Dynamic coordination bonds are key to maintaining catalyst activity after surface modification.
• Ligand-mediated recovery offers a sustainable strategy for using MOPs as homogeneous catalysts.