Bioreductive molecular probe: fluorescence signalling upon reduction of an azo group.

The intramolecular heterodimer probe 4-O-dabsyl-2-O-dansyl-myo-inositol-1,3,5-orthoformate undergoes biomimetic reduction of the azo bond in the dabsyl group to give a fluorescence emission band at 560 nm. This is attributed to the loss of energy transfer between the fluorophore (dansyl) and quencher (dabsyl) groups as a result of the formation of 4-O-(4-aminobenzene sulfonyl)-2-O-dansyl-myo-inositol-1,3,5-orthoformate.