ATTO 740 together with ATTO 725 belongs to a new generation of fluorescent labels for the near infrared spectral region. Characteristic features of the new dye are strong absorption and fluorescence, high thermal and exceptional photostability, and only little triplet formation. The dye is very stable at pH-values below 7.5, yet degrades, depending on the actual pH, more or less fast in alkaline solution.

ATTO 740 and its derivatives are supplied as solvent-free perchlorate salts. The dye is moderately hydrophilic. Its NHS-ester and maleimide show excellent solubility in polar solvents like DMF, DMSO or acetonitrile. For details of coupling see our recommended labeling procedure (PDF). The fluorescence is excited most efficiently in the range 720 - 755 nm.