Effect of Structure and Conformation on Fluorescence Properties in Novel Coumarin-based Mannich Base Dyes

Twelve novel coumarin-based Mannich base dyes have been synthesized via introducing functional aminomethyl group at the 8 position of coumarin ring by Mannich reaction and their chemical structures were confirmed by IR, H-1 NMR, MS and elemental analysis. Moreover, the fluorescence intensities and relative quantum yields of all the dyes were measured and studied. The results illustrated that the heavy atom effect was obvious in our designed system and there was a relationship between the structures, the conformations and the fluorescence spectra of the coumarins. Meanwhile, the present beta-CD titration experiment illustrated that the aniline nitrogen atom was closely related to the photoinduced electron transfer (PET) course and the PET course was carried out via a conformational control mechanism.