Luminescence properties of dual fluorescent pyrene derivatives used as DNA probe molecule.

We examined the dual fluorescence mechanism of 8-[4-(dimethylamino)phenyl]-N-2-propynyl-1-pyrenecarbox-amide (PyADMA) in polar solvent. The emission band appeared on the short wavelength side does not depend on the solvent polarity. On the other hand, the red shifted emission band depends on solvent polarity. On the face of it, the phenomenon is similar to intramolecular charge transfer (ICT) dynamics of 4-dimethylamino benzonitrile (DMABN). However, direct absorption band from ground state to ICT state is observed on the fluorescence excitation spectrum at room temperature. It is suggest that PyADMA would emit from both S(1) and S(2) state against the Kasha rule. On the other hand, we also examined the interaction between PyADMA and nucleoside which composing PyDMA-U in water solution. We found out that dynamics of excited states of PyADMA monomer is different from them of PyDMA-U.