Fluorescence Properties And Mechanism Study Of 1, 8-Naphthalimide Derivatives Doped In Gel Materials

A series of 1,8-naphthalimide derivatives were synthesized from 4-substituted-1,8-naphthalimide. The structures of the compounds were determined by FT-IR and 1D,2D NMR spectra. The fluorescence spectra showed the fluorescence intensity of the compounds in dilute solution is much higher than that of the raw materials.By using 1,8-naphthalimide derivatives, a series of fluorescence membranes were prepared by sol-gel process with APTES and GPTMS as different matrixes. The obtained samples formed stable and homogeneous films on glass. High fluorescence emission from the samples with APTES as matrix was observed. The factors, such as the concentration, the substituent, the solvent and the properties of matrix, which influenced the fluorescence intensity were studied. The fluorescence intensity of the samples with APTES showed a significant increase followed with decrease according to the increased concentration of 1,8-naphthalimide derivatives, the maximum observed at 0.06% molar concentration. Samples with different substituent showed very similar maximum fluorescence intensity. Samples with different matrix showed a great difference in the fluorescence intensity. We conjectured the aggregation form and the molecular motion may be the main factor for the change of fluorescence intensity in the solid state.With the purpose of studying the relationship between the fluorescence intensity and the molecular motion of 1,8-naphthalimide derivatives in membranes, deuterium-substituted 4-nitryl-1,8-naphthalene anhydride (D-NNA) was synthesized from deuterium-substituted acenaphthene. D-NNA was then doped into APTES under same conditions. XRD and 2H NMR experiments were performed to determine the aggregation and the molecular motion of 1,8-naphthalimide derivatives in the complex system.