Homodimeric monomethine cyanine dyes SOSO-1 and TOTO-1-6C—synthesis and fluorescence properties in the presence of nucleic acids

Abstract

Two new homodimeric asymmetric monomethine cyanine dyes SOSO-1 and TOTO-1- 6C bearing four and six positive charges respectively have been synthesized. The longest wavelength absorption maxima of both dyes lie between 495 and 520 nm; the molar absorptivities are between 110,000 and 150,000 l mol −1 cm −1. SOSO-1 and TOTO-1-6C do not fluoresce in TE buffer and bidistilled water but become strongly fluorescent upon binding to dsDNA. The fluorescence maxima are at 540.4 and 534.4 nm and the fluorescence quantum yields are 0.25 and 0.35, respectively.