Organosilane-Patterned Paper-based Colorimetric Sensors for High-Throughput Screening of Cross-Coupling Reactions with Aryl Bromides

Abstract

An organosilane-patterned paper-based colorimetric sensor for bromides was developed using the 4-(2-pyridylazo) resorcinol (PAR)-Hg2+ complex and patterned hydrophobic paper. The red color of the (PAR)-Hg2+ spot was converted to yellow by ligand exchange between PAR and added bromide ions. This paper-based sensor was applied to detect the extent of conversion of aryl bromides in palladium-catalyzed coupling reactions such as Stille, Suzuki, Heck, direct arylation and decarboxylative coupling. A good correlation was demonstrated between the conversion of paper-based sensor and conversion of gas chromatography.