HBr-Regulated Smart 2D Copper-Organic Framework for Highly Efficient and Selective Photocatalytic Oxidation

Area of Science:

• Materials Science
• Catalysis
• Nanotechnology

Background:

• Smart covalent organic frameworks (COFs) are emerging catalysts with tunable properties.
• Dynamic structure-activity relationships in stimuli-responsive COFs are under-explored.
• Need for advanced catalysts with controlled photocatalytic pathways and selectivity.

Purpose of the Study:

• To design and synthesize a smart metal covalent organic framework (Cu3-MCOF) with dual responsiveness.
• To investigate the stimulus-triggered modulation of photocatalytic properties and reaction pathways.
• To elucidate the structure-activity relationships governing enhanced photocatalysis.

Main Methods:

• Synthesis of a smart metal covalent organic framework (Cu3-MCOF) using copper cyclic trinuclear clusters.
• Stimulation with hydrogen bromide (HBr) to induce reversible imine protonation and cluster reconstruction.
• Characterization using spectroscopic studies and density functional theory (DFT) calculations.

Main Results:

• Cu3-MCOF exhibited dual responsiveness to HBr, leading to optical gap narrowing and absorption redshift.
• Photocatalytic activity for α-terpinene oxidation increased 40-fold with >99% superoxide radical selectivity.
• Enhanced photocatalytic bromination of 1,2,4-trimethoxybenzene was also observed.
• Stimulus-induced changes promoted electron localization, charge separation, and selective superoxide radical generation.

Conclusions:

• The developed smart MCOF acts as a dynamic photocatalyst based on metal-cluster nodes.
• Stimulus-driven regulation of photocatalytic pathways and selectivity was successfully demonstrated.
• This work provides fundamental insights into designing advanced stimuli-responsive catalytic materials.