Fluorogenic dye azides are fluorophores that have a low or no fluorescence in their azide form. This fluorogenic dye azides restore or strongly increase their fluorescence upon reaction with an alkyne in the presence of copper to form the triazole. This opens up the possibility to monitor a Copper-catalyzed Click reaction in real time and the detection of DNA in probes without requiring washing steps to remove the unreacted fluorogenic dye azides.1
1. K. Li, L.A. Lee, X. Lu, and Q. Wang, BioTechniques, 2010, 49, 525-7.