Synthesis and Fluorescence Properties of New Enaminenaphthalimides

Abstract

The first 4-enamine-N-methyl-1,8-naphthalimides (amine = piperidine, pyrrolidine, morpholine, Prⁿ₂NH, Prⁱ₂NH) are reported. The X-ray crystal structure of the piperidine derivative confirmed the E-stereochemistry and showed strong Π–Π stacking in the unit cell. The enamines are strongly fluorescent and quantum yields do not vary with the pK_b of the amine. The solvent dependence of λ _abs and λ _flu is consistent with significant charge separation in the excited state.