Synthesis and fluorescence study of naphthalimide-coumarin, naphthalimide-luminol conjugates.

Fluorescent naphthalimide-coumarin and naphthalimide-luminol conjugates were prepared by nucleophilic substitution reaction. The synthesized conjugates were characterized by (1)H-NMR, (13)C-NMR, mass and IR spectra. The absorption and fluorescence of these conjugates revealed that naphthalimide-luminol conjugates are more fluorescent than the naphthalimide-coumarin conjugates. In proton accepting DMSO solvent the fluorescence of the conjugates was quenched, while in proton donating ethanol solvent enhanced fluorescence was noticed. Based on the excitation maxima and fluorescence maxima it was found that in naphthalimide-coumarin conjugates coumarin acting as donor and naphthalimide acting as acceptor where as in naphthalimide-luminol conjugates naphthalimide acts as donor and luminol acts as acceptor.