CF™640R picolyl azide reacts with alkyne to form 1,2,3-triazole by 1,3-dipolar Huisgen cycloaddition through the use of a much lower copper (I) concentration without sacrificing reaction efficiency. CF™640R is a novel rhodamine-based dye spectrally very similar to Cy®5 and Alexa Fluor® 647. CF™640R is much brighter than Cy®5 and at least as bright as Alexa Fluor® 647 when excited at 633 or 635 nm. However, the most important advantage of CF™640R is its exceptional photostability. CF™640R is far more photostable than the cyanine-based dyes Cy®5 and Alexa Fluor® 647. It is also more photostable than Atto 647N, a dye that has been extensively used in single molecule-based imaging. CF™640R is also extremely water-soluble and pH-insensitive. These properties make CF™640R a much better alternative to Cy®5, Alexa Fluor® 647 and other spectrally similar dyes. Please download the CF™640R dye flyer for more details.