New fluorescent markers for the red region.

Two new classes of fluorescent dyes have been developed as labels for the red region of the spectrum: amide-bridged benzopyrylium dyes and carbopyronin dyes. The fluorescence quantum yield ranges from 20 to 90%, the decay time from 1 to 4 ns. The pH- and solvent-dependence of absorption and fluorescence are described in detail. Covalent attachment is possible via activated carboxyl groups.