BDP 581/591 is a borondipyrromethene dye with a conjugated olefinic system. It can be used either as a regular fluorophore, or as a probe for the detection of reactive oxygen species (ROS); after oxidation, its fluorescence moves to the green part of the spectrum.
This is a version of the dye containing cyclooctyne. The DBCO (azodibenzocyclooctyne) moiety can be conjugated with azides yielding stable triazole conjugates.