Synthesis and fluorescence properties of polymerizable 1, 8-naphthalimide derivatives doped polysiloxane materials

Three polymerizable 1, 8-naphthalimide derivatives were synthesized and their photophysical properties in DMSO solution were determined. ¹H NMR spectra of these compounds revealed the electronic environment surrounding the hydrogen nucleus which is proved to be related to their photophysical properties. Highly fluorescent polysiloxane materials were prepared by condensation of polymerizable 1, 8-naphthalimides derivatives with γ-aminopropyl triethoxysilane(APTES) by the sol-gel process. It was found that all of the 1, 8-naphthalimides derivatives with different substituent at C-4 position possess the best fluorescence intensity while doped in polysiloxane at molar fraction of 0.06%. ²⁹Si MAS NMR and fluorescence measurement results show that the degree of condensation of polysiloxane also affect the fluorescence of materials, which hints that the molecular motion is the stronger factor than substituent effect on the fluorescence of the solid materials.