Synthesis and characterization of periodic mesoporous organosilicas containing aromatic imides for applications in the energy sector

Abstract

The project´s goal is the synthesis and characterization of mesoporous silicas functionalized with aromatic imides. The materials will be synthesized by the co-condensation, in the presence of a surfactant, of an inorganic silica source (tetraethylorthosilicate) (TEOS) with an organic silica source containing the aromatic imide (N,N´-bis(3-(triethoxysilyl)propyl)-1,4,5,8-naphthalenediimide) (TEPNDI). This method produces periodic mesoporous organosilicas (PMO), where the organic modifier is integral part of the pore walls. A series of samples with varying TEOS/TEPNDI molar ratios will be prepared. The new materials (to be named heretofore PMO-NDI) will be characterized by several techniques, such as small-angle X-ray scattering, N2 adsorption isotherms, transmission electron microscopy and UV-visible absorption and fluorescence spectroscopies. Applications for these materials in the energy sector will be devised, such as color-adjustable LEDs. For this purpose, a second dye will be doped into the pores of PMO-NDI, such that Förster resonant energy transfer (FRET) to the guest dye will occur upon excitation of the host naphthalenediimide (NDI) in the pore walls. This should result in dual emission, whose colors could be controlled by the degree of doping. A trichromophoric FRET system will also be constructed, with two different dyes simultaneously doped into the pores of PMO-NDI. Another possible application for PMO-NDI is as semiconducting nanowires. For this goal, the NDI units will be reduced with sodium dithionite to give imide free radicals, and the conductivity of the materials will be measured. Finally, the PMO-NDI will be tested as heterogeneous catalysts in the photodegradation of pollutants, such as methylene blue and petroleum asphaltenes. Asphaltene degradation is a very important issue, both for petroleum refining as well as in the remediation of oil spills. (AU)