henylazo)benzoic acid (HAZA) scaffold, the orthogonally protected difunctional azo–arene cleavablelinker 26 was designed and synthesized. Selective linker deprotection and derivatization was performed by introducing an alkyne reactive group and a biotin affinity tag. This optimized azo–arene cleavablelinker led to a total cleavage in less than 10 s with only 1 mM dithionite. Similar results were