Photophysical and Complexation Behavior of (4-Dimethylamino-benzylidene)-(4,6-dimethyl-pyrimidin-2-yl)-amine

The absorption and fluorescence characteristics of (4‐dimethylamino‐benzylidene)‐(4,6‐dimethyl‐pyrimidin‐2‐yl)‐amine (SB) have been investigated in different solvents. Both the absorption and emission spectra of SB exhibit red shifts as the solvent polarity increases. This indicats a change in dipole moment of molecules upon excitation as a result of intramolecular charge transfer interaction. The fluorescence quantum yield depends strongly on the properties of the solvents, which was discussed on the bases of positive and negative solvatokinetic effects. The effect of some divalent transition metal ions such as Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, and Hg²⁺on the absorption and fluorescence spectra of SB is also investigated. The results were consistent with formation of highly colored metal‐ SB complex which is responsible for the extreme quenching of the fluorescence of SB. The variations of both the formation constant of the complex and Stern‐Volmer constant were correlated with the electronic structure of the used metal ion.