AF 568 carboxylic acid is a non-reactive form of the orange fluorescent dye AF 568. It exhibits an absorption wavelength range of 590-720 nm (FRET) and an emission wavelength range of 515-720 nm. AF 568 alkyne can form stable covalent bonds with amino-containing molecules through its carboxylic acid group. It can also participate in a copper-catalyzed azide-alkyne cycloaddition reaction (CuAAc) with molecules containing alkyne groups. Additionally, it is capable of engaging in strain-promoted azide-alkyne cycloaddition (SPAAC) with compounds containing DBCO or BCN groups.