Molecular Junction Polyoxotungstate-based Copper-Organic Frameworks for Photocatalytic Cross-Dehydrogenative...

Area of Science:

• Catalysis
• Materials Science
• Organic Chemistry

Background:

• Traditional cross-dehydrogenative coupling (CDC) methods often use toxic solvents and noble metals, leading to low atom economy and sustainability concerns.
• Simultaneous C─H bond activation in alkynes and radical formation in amines is challenging for C─C coupling.
• Developing sustainable and efficient catalytic systems for CDC reactions is crucial for modern synthesis.

Purpose of the Study:

• To develop a novel, sustainable photocatalytic system for the cross-dehydrogenative coupling (CDC) of tertiary amines and terminal alkynes.
• To synthesize and characterize polyoxotungstate-based copper-organic frameworks (Cu-POMOFs) for efficient photocatalysis.
• To achieve high yields in C─C bond formation using green solvents, light, and air.

Main Methods:

• Synthesis and characterization of three molecular junction polyoxotungstate-based copper-organic frameworks (Cu-POMOF-1, Cu-POMOF-2, Cu-POMOF-3).
• Photocatalytic cross-dehydrogenative coupling reactions utilizing the synthesized Cu-POMOFs in dimethyl carbonate under visible light and air.
• Optimization of the catalytic system to identify the most effective framework for the reaction.

Main Results:

• The developed Cu-POMOFs demonstrated efficient photocatalytic activity in the CDC reaction.
• Cu-POMOF-3, featuring a 3D topological structure with integrated polyoxotungstate and Cu sites, achieved a 98% yield in the coupling of tertiary amines and terminal alkynes.
• The reaction system proved to be scalable, with a 2.06 g batch experiment, and operated effectively under natural sunlight and ambient air.

Conclusions:

• Polyoxotungstate-based copper-organic frameworks (Cu-POMOFs) represent a novel and efficient class of photocatalysts for C─C bond formation via CDC reactions.
• The optimized Cu-POMOF-3 system offers a green, sustainable, and scalable alternative to traditional methods for synthesizing C─C bonds.
• This work highlights the potential of molecular junction POMOFs in advancing sustainable catalysis and organic synthesis.