Embedding of bis-vanillin and bis-eugenol on Porous of Mesoporous Silica: Evaluation of Surface Interaction Between These Materials

MANCINI PEDRO; FERRETI CRISTIAN; GUNTERO VANINA; CAINELLI MAURO, KNEETEMAN MARIA

Santa Fe

Congreso; VI San Luis School and Conference on Surfaces, Interfaces and Catalysis; 2018

In recent years, porous materials such as mesoporous silica of different types have been employed for hosting and promote delivery of various molecules. The high surface-to-volume ratio in these materials and meso-scale pores make them useful for heterogeneous catalysis, ion exchange, gas sensing and alternate energy applications [1,2]. In this work, the selected support for encapsulation of organic compound was SBA-15. According to development of green sustainable synthetic methods, we proposed the synthesis of SBA-15 using microwave irradiation (MW). Organic molecules that were embedding into SBA-15 were bis-vanillin (BV) and bis-eugenol (BE) through MW. For investigating the state of compound biphenyls within the channels of hybrid material and the properties of composites, we characterize these hybrid mesoporous materials through 29Si NMR, elemental analysis, nitrogen adsorption-desorption isotherms, Fourier-transform infrared spectroscopy (FTIR), UV-vis and fluorescence spectroscopy. Results of the nitrogen adsorption-desorption isotherms and the pore size distribution curves of SBA-15, BV-SBA and BE-SBA showed mesoporous silicas are of type IV with H1 hysteresis loop at relative pressure (P/P0) of 0.7-0.98 that is representative of the mesoporous cylindrical. The values of the specific surface area, pore volume and pore diameter of SBA-15 agree with those reported in the literature. The encapsulation of BV and BE into SBA-15 caused a slight increase of average pore diameter, a reduction of specific surface area and a pore volume almost unchanged. Mesoporous silica SBA-15 itself showed no fluorescence, whereas BV showed an excitation band at 601 nm (λEM=400 nm) and BE presented an excitation band at 595 nm (λEM=420 nm). The mesoporous hybrid materials of BV-SBA and BE-SBA gave a sensitive fluorescence response, at the same wavelength as the free precursors. Similar results were obtained by analysis UV-Vis. The spectroscopic characterization by FTIR and 29Si NMR together with textural analysis confirmed that the ordered structure of SBA-15 can be maintained after the inclusion of the BV and BE host molecules. These organic molecules interact weakly with the walls of SBA-15 through hydrogen bonds, producing no chemical changes in the structure of the silica. The attractive characteristic of these systems is the possibility of activating the release of the organic molecules encapsulated into SBA-15.