Mesoporous silica is a very suitable carrier for preparation of sensors for detection of explosive compounds with high selectivity and rapid responsiveness by incorporating chemical sensing units into silica films. Three types of porphyrin-doped silica with mesoporous and amorphous structures were prepared. 5,10,15,20-tetrakis(4carboxyphenyl)porphyrin was synthesized in two steps starting from p-methoxycarbonylbenzaldehyde. 5,10,15,20tetrakis(4-(methoxycarbonyl) phenyl) porphyrin (1a) was hydrolyzed with trifluoroacetic acid (TFA) to produce 5,10,15,20-tetrakis(4-carboxyphenyl) porphyrin (1b) in 100 % yield. Different kinds of silica such as Hexagonal SBA-15 (SBA-15(Hex)), Spherical SBA-15 (SBA-15(Sp)) and commercial SiO 2 (SiO 2 (Ald)) were functionalized using 3-aminopropyltriethoxysilane (3-APS). Porphyrin with carboxylic substituent was reacted with N-hydroxysuccinimide (NHS) and N,N -dicyclohexylcarbodiimide (DCC) to produce 5-[4-(succinimidyloxycarbonyl)phenyl]-10,15,20tri(4-carboxyphenyl)porphyrin (H 2 SPTCPP) and grafted to the surface of modified silica to obtain porphyrin-doped silica materials. Results suggest that the synthetic route Electronic supplementary material The online version of this article (achieves a high content of porphyrin incorporated to the support. The percentage of porphyrin incorporated to the support, which is higher in the case of SBA-15(Sp) with higher surface area and containing a larger number of silanol groups available for grafting, is directly related to the catalytic activity. Time-dependent fluorescence quenching of porphyrin-doped silica films was studied for three different mesostructures and it showed a rapid quenching upon exposure to a trace amount of TNT vapor due to the high surface area and highly ordered structure of silica.
Ethylene polymerization catalysts have been prepared by grafting chromium (III) nitrate onto Al/SBA-15 and Ti/SBA-15 mesoporous materials. A combination of XRD, nitrogen adsorption, TEM, and inductively coupled plasma-atomic emission spectroscopy (ICP-AES), were used to characterize the catalysts. Polymerization activity of Cr/SBA-15 catalyst is significantly improved by Al or Ti insertion to the supports. Particularly, the chromium catalyst prepared with Ti/SBA-15 support is more active than Al/SBA-15 catalyst.
Three kinds of heteroaldehydes, N-(3-triethoxysilylpropyl)-4-formyl benzamide (TPHA/SiO 2), were prepared by the reaction of terephthalaldehydic acid with different silica supports such as hexagonal SBA-15, spherical SBA-15 and amorphous SiO 2 for comparison purposes. Anchoring of this aldehyde to different supports allows the synthesis of mono-substituted porphyrins without the production of di-, tri-and tetra-substituted porphyrin side products. The exclusion of the aforementioned side products during the synthesis of monosubstituted porphyrins greatly reduced the complexity during purification of the product. Absorption spectrophotometry was performed on silica gel immobilizing porphyrin (CPTTP), free base tetraphenylporphyrin (H 2 TPP) and heteroaldehydes (TPHA/SiO 2) using UV-Visible instrument and confirmed the presence of porphyrin on the structure of CPTTP.
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