CF® dye azide reacts with alkyne to form 1,2,3-triazole by copper(I) catalyzed 1,3-dipolar Huisgen cycloaddition. It could also undergo Staudinger ligation with a phosphine containing compound. CF® dyes are Biotium's line of next-generation fluorescent dyes with advantages in brightness, photostability, and conjugate specificity compared to other fluorescent dyes. Far-red fluorescent CF®647 dye has excitation/emission at 650/665 nm.