Fluorescent Molecular Probes II. The Synthesis, Spectral Properties and Use of Fluorescent Solvatochromic Dapoxyl Dyes

Article abstract of DOI:10.1111/j.1751-1097.1997.tb03168.x

2,5-Diphenyloxazoles that embody a dimethylamino group at position 4 of the 5-phenyl ring and a sulfonyl group at position 4 of the 2-phenyl ring were prepared as new fluorescent solvatochromic dyes. In these molecules, there is a "push-pull" electron transfer system from the 5-phenyl moiety to the 2-phenyl ring. These compounds show strong solvent-dependent fluorescence that is well correlated with the empirical solvent polarity parameter E_T (30). The solvent polarity dependence suggests that the fluorescence arises from an intramolecular charge transfer. The fluorescence-environment dependence, long emission wavelength, large extinction coefficients, high fluorescence quantum yields and large Stokes shift of the fluorophores can be used to develop ultrasensitive fluorescent molecular probes to study a variety of biological events and processes.