Anthraquinone-Modified Silica Nanoparticles as Heterogeneous Photocatalyst for the Oxidative Hydroxylation of Arylboronic Acids

MARTIN, M. GUADALUPE; LÁZARO-MÁRTINEZ, JUAN MANUEL; MARTÍN, SANDRA E; UBERMAN, PAULA M; BUDÉN, M. EUGENIA

Chemistry - A European Journal

John Wiley and Sons Inc

Año: 2023

In this work, the synthesis and characterization of aheterogeneous photocatalyst based on spherical silica nanoparticlessuperficially modified with anthraquinone 2-carboxylic acid (AQCOOH) are presented. The nanomaterial was characterized by TEM,SEM, FT-IR, diffuse reflectance, fluorescence, NMR, DLS, XRD andXPS. These analyses confirm the covalent linking of AQ-COOH withthe NH2 functionality in the nanomaterial and, more importantly, thephotocatalyst retains its photophysical properties once bound. Theheterogeneous photocatalyst was successfully employed in theaerobic hydroxylation of arylboronic acids to phenols undersustainable reaction conditions. Phenols were obtained in high yields(up to 100 %) with low catalyst loading (3.5 mol %), reaching TOFvalues of 3.7 h-1. Using 2-propanol as solvent at room temperature,the visible light photocatalysis produced H2O2 as a key intermediateto promote the aerobic hydroxylation of arylboronic acids. Theheterogeneous photocatalyst was reused at least 5 times, withoutmodification of the nanomaterial structure and morphology. Thissimple heterogeneous system showed great catalytic activity undersustainable reaction conditions.