Water-soluble rylene dyes as high-performance colorants for the staining of cells

The synthesis of perylene and terrylene chromophores carrying a single poly(ethylene oxide) chain is presented. These chromophores reveal a strong solvatochromic behavior: High fluorescence in nonpolar solvents and weak fluorescence in polar solvents which is mainly attributed to aggregation. Therefore, such chromophores are attractive candidates as sensitive fluorescent probes reflecting the polarity of their environment. In particular, their suitability for the staining of cellular membranes is presented in detail.