This is an azide for copper catalyzed and copper free Click chemistry labeling with BDP TR, a bright red emitting fluorophore. BDP TR is an alternative to ROX and Texas Red. This fluorophore is based on borondipyrromethene scaffold, and contains aryl substituents to match its absorption and emission to ROX/Texas Red channel.
ROX and Texas Red dyes are prone to oxidation, BDP TR is much more resilient to oxidants. Its brightness and photostability is also very high.