Enhancing photocatalytic performance of atom transfer radical addition (ATRA) reactions in water using immobilized 10-Phenylphenothiazine catalysts on mesoporous silica supports

Abstract

The development of catalysts is crucial for sustainable chemistry, and heterogeneous catalysis, specifically, can be environmentally friendly and recyclable. Catalyst immobilization in materials has been explored, in which mesoporous silica materials have shown outstanding results in catalysis. Photocatalysis has also gained attention, providing solutions for organic synthesis and late-state functionalization, mainly using homogeneous catalysts and organic solvents. The use of aqueous media for photocatalytic reactions is particularly attractive from a sustainability perspective yet can influence reaction chemoselectivity. However, poor solubility of the organic substrates and the catalyst limits photocatalytic methods in water. Mesoporous silicas are water-stable materials suitable for catalytic applications in such media, including photocatalysis. In this work, we demonstrate an atom transfer radical addition (ATRA) reaction in water using immobilized 10-phenylphenothiazine (PTH) catalyst on different mesoporous silica supports, showing improved photocatalytic performance compared to homogeneous conditions and substrate selectivity depending on the hydrophobicity of the alkene.