4- (2-Azidoethyl) phenol

4- (2-Azidoethyl) phenol is a bifunctional small molecule probe featuring both a phenolic hydroxyl group and an azide structure. Its core application lies in the phenol moiety serving as a substrate for APEX2 (ascorbate peroxidase), generating reactive radicals in situ in the presence of H2O2 to label neighboring proteins. Concurrently, the terminal azide group can be linked to alkyne-labeled detection molecules via copper-catalyzed azide-alkyne cycloaddition (CuAAC) to achieve biotinylation or fluorescence visualization. 4- (2-Azidoethyl) phenol is widely used in proximity labeling-based proteomics research.