7-(Diethylamino)-3-(4-isothiocyanatophenyl)-4-methylchromen-2-one

7-Diethylamino-3-(4'-isothiocyanatophenyl)-4-methylcoumarin (CPI) is a fluorescent labeling reagent that reacts covalently with amino groups. It is a isothiocyanate derivative of coumarin. It has a high quantum yield (0.75-0.78), long wavelength excitation, and high stability, which makes it ideally suited as fluorescent label for proteins. The quantum yield is little affected by the pH of solutions. Spectral Data: lambdaem = 396nm, lambdaem = 478nm.