Synthesis And Photophysical Study Of Naphthalimides Doped Polysiloxane Fluorescent Materials

The polymerizable naphthalimides materials were synthesized with 4- substituted -1, 8-naphthalic anhydride (XNA). The structure of the compound was determined by 1D (¹H and ¹³C NMR) and 2D NMR techniques including ¹H-¹H COSY, HMBC and HSQC. By using the upper polymerizable naphthalimides, a series of novel fluorescent polysiloxane material containing XNA groups was designed and prepared by sol-gel process. In this way, XNA was introduced into the polysiloxane system via chemical linkage. The obtained samples can form homogeneous and transparent membranes on glass or some plastic substrates. High green fluorescence emission from the samples was observed.The photophysical properties of the samples were studied. The factors, such as the linkage, the concentration, the electronic effects, and the aggregation configuration of XNA in the samples, which influenced the fluorescent properties, were also studied. The results show that fluorescent intensities of chemical linked samples are much higher than their physically doped counterparts and the dilute solution of XNA. The fluorescence intensity of chemically bridged samples showed a dramatic increase followed with decrease when the XNA concentration increased, the maximum reached at about 0.06% molar concentration. It is intriguing to note that in this case, the electronic effect of the substitute became non-important. Samples with different substituent show very similar maximum fluorescence intensity. According to the results of UV-vis spectra and fluorescence spectra, we consider that J-aggregation was formed in the XNA-contained polysiloxane system. This may be the main reason of the fluorescent intensity increasing.