Colorimetric hypochlorite detection using an azobenzene acid in pure aqueous solutions and real application in tap water

Colorimetric azobenzene based chemosensor 1 was designed for the detection of hypochlorite by fully utilizing the oxidation property of hypochlorite and different coordinating properties of Cu+ and Cu2+ in pure aqueous solutions. In the presence of cuprous ions, the red solution of chemosensor 1 changed to yellow, upon the addition of hypochlorite. Other anions, including H2PO42−, H2PO4−, SO42−, Cl−, ClO4−, HSO3−, Br−, PO43−, CO32−, I−, HCO3−, SO32−, F−, AcO−, HSO4−, NO2−, ClO3−, IO3− and H2O2, nearly gave no influence to the probing behavior of chemosensor 1 towards hypochlorite, making chemosensor 1 a highly selective and sensitive hypochlorite chemosensor in pure aqueous solutions.