Cyanine3.5 carboxylic acid chloride is an anthocyanin dye. Cyanine3.5 carboxylic acid chloride is Cyanine3.5 free unactivated monofunctional carboxylic acid and can be used as a reference or control for non-reactive dye. Cyanine3.5 also is an analog of Cy3.5 fluorophore.