Preparation of hybrid bimodal mesoporous silicas loaded with various capacity of 1,8-naphthalic anhydride and their luminescent properties

The novel luminescent hybrid bimodal mesoporous silicas (LHMS) modified with different amount of (3-aminopropyl)triethoxysilane (APTES) on the mesoporous surface and then loaded with various capacity of 1,8-naphthalic anhydride (NA) were synthesized through two-step route. The relative hybrid materials were characterized by XRD, N2 adsorption–desorption isotherms, 29Si NMR, TG and PL, and the results show that the bimodal pore system is a suitable host matrix for the fluorescent materials. After modification by using propylamine group as a linker, the surface area and the pore volume of resultant samples decreased with the increasing concentration of APTES in tetrahydrofuran solution and the amount of the NA, respectively. The luminescent behaviors of LHMS indicated that the fluorescence intensity and position of emission spectra depended on the various preparation parameters, especially including the concentration of APTES in the tetrahydrofuran solution during the modification process and mass ratio of NA with the modified mesoporous silicas. Particularly, their blue-shift effectiveness of the position of the emission peak was remarkable with the loading NA amount decreased. The detailed mechanism was also discussed.