Preparation And Fluorescence Study Of Composite Gels Of A Series Of 1,8-naphthalimideDerivatives With Cellulose And Polysilsesquioxane

1,8-naphthalimide derivatives have beautiful color, strong fluorescence intensity, and highly thermal stability. They can be obtained by rectifying coal tar, which is abundant in China. As a kind of intramolecular charge transfer compounds with wide application prospect,1,8-naphthalimide derivatives have been studied since 1970s, and are continuing unabated in recent years. Cellulose is the most abundant regenerative resource, and important chemical raw material. Because of owning both organic groups and inorganic framework, polysilsesquioxane has excellent performance, and is widely used. In this work, eight 1,8-naphthalimide derivatives with different substituent groups in O atom of anhydride naphthalene or 4-position of naphthalene were synthesized. Then they were compounded with cellulose and polysilsesquioxane, preparing soft and hard materials with excellent fluorescent properties. A brief summary of results are as follows.1、Eight 1,8-naphthalimide derivatives with different substituent groups in O atom of anhydride naphthalene or 4-position of naphthalene were synthesized by the optimization of experimental conditions. Complete interpretation of eight compounds were completed by 1H,13C,1H-1H COSY, DEPT-135, HSQC, HMBC. Then their photophysics properties were studied in different solvent DMF/DMSO/ CH2CI2/THF. As different substituents and interactions between solute and solvent, various compounds have significant difference in fluorescence emission spectra in various solvents.2、Cellulose can be dissolved by green solvent LiOH/urea/H2O at-13.5℃ Four 1,8-naphthalimide derivatives with high fluorescence intensity were chosen to dope with cellulose by cross-linking agent epichlorohydrin, preparing biocompatible fluorescent hydrogel. And the photophysics of them were studied. As micromolecule and cellulose were doped with gradient concentration, the best doped concentration were obtained based on max pi intensity. And we came to a conclusion that fluorescence intensity of these doped materials is related to fluorescence intensity of fluorescent micromolecule.3、Three 1,8-naphthalimide derivatives with significant gap in fluorescence intensity were doped with polysilsesquioxane by a sol-gel method, preparing three plural gels all with high fluorescence intensity. Photophysics of the plural gels were studied. Molecular motion instead of substituent effect is especially important in fluorescent polysilsesquioxane materials. Exciton division theory was used to explain the mechanism of fluorescence enhancement. It is found that many traditionally weakly fluorescent or non-fluorescent chromophoric organics may be used to prepare highly fluorescent materials.