Photochromic Cu-TiO₂ Nanocatalysts for Visible-Light-Triggered C-Cl Activation and Selective Molecular Assembly

Area of Science:

• Materials Science
• Photochemistry
• Organic Synthesis

Background:

• Selective C-Cl bond activation for pharmaceutical synthesis via cross-coupling is crucial but challenging.
• Visible-light photoredox catalysis offers a sustainable approach, yet activating unactivated C-Cl bonds remains difficult.

Purpose of the Study:

• To develop a cooperative photoredox catalysis system for efficient and selective activation of benzyl chloride (BnCl) C-Cl bonds.
• To synthesize C-C and C-O bond-containing pharmaceuticals using visible light.

Main Methods:

• Utilized photochromic copper-doped titanium dioxide (Cu-TiO2) nanoparticles as a cooperative catalyst.
• Employed visible-light photoredox catalysis for BnCl activation and subsequent cross-coupling reactions.
• Conducted mechanistic investigations and theoretical calculations to elucidate the catalytic process.

Main Results:

• Achieved efficient activation of benzyl chloride (BnCl) and selective formation of C-C and C-O bonds.
• Demonstrated high yield (>96%), selectivity (>99%), and stability (>30 days) in bibenzyl homocoupling.
• Successfully synthesized pharmaceuticals like 4-(benzyloxy)phenol (monobenzone) and benzylated 1,4-benzoquinone.

Conclusions:

• Cu doping in TiO2 enhances BnCl coordination, and photochromism-induced Cu+/0 sites facilitate C-Cl bond activation.
• The system enables selective pharmaceutical synthesis via cooperative photoreduction of BnCl and photooxidation of p-phenol.
• Established a framework for designing photochromic catalysts for C-Cl bond functionalization in photoredox systems.