3,6 diacetoxy phthalonitrile

3,6-diacetoxy Phthalonitrile is a fluorescent probe for monitoring intracellular pH by flow cytometry in living cells. It rapidly crosses cell membranes and is cleaved by cytosolic esterases to form the fluorescent pH indicator 2,3-dicyano-hydroquinone (DCH), which is excited at UV wavelengths. DCH can be excited at 351 nm, with pH-dependent emission in the range of 450-476 nm (pH 5.0-10.0) using a potassium-based buffer.

6-Chloro-3-indoxyl-α-D-mannopyranoside serves as a chromogenic substrate for the enzyme α-mannosidase, generating a salmon-colored precipitate upon enzymatic cleavage.