Direct synthesis and catalytic applications of ordered large pore aminopropyl-functionalized SBA-15 mesoporous materials.

SBA-15 mesoporous silica has been functionalized with aminopropyl groups through a simple co-condensation approach of tetraethyl orthosilicate (TEOS) and (3-aminopropyl)triethoxysilane (APTES) using amphiphilic block copolymers under acidic conditions. The organic-modified SBA-15 materials have hexagonal crystallographic order, pore diameter up to 60 A, and the content of aminopropyl groups up to 2.3 mmol g(-1). The influences of TEOS prehydrolysis period and APTES concentration on the crystallographic order, pore size, surface area, and pore volume were examined. TEOS prehydrolysis prior to the addition of APTES was found essential to obtain well-ordered mesoporous materials with amino functionality. The amount of APTES incorporated in the silica framework increased with the APTES concentration in the synthesis gel, while the ordering of the mesoporous structure gradually decreased. Analysis with TG, IR, and solid state NMR spectra demonstrated that the aminopropyl groups incorporated in SBA-15 were not decomposed during the preparation procedure and the surfactant P123 was fully removed through ethanol extraction. The modified SBA-15 was an excellent base catalyst in Knoevenagel and Michael addition reactions.

Preparation of ordered large pore SBA-15 silica functionalized with aminopropyl groups through one-pot synthesis.

Highly ordered large pore SBA-15 silica functionalized with up to 16% aminopropyl groups, which gave high catalytic activity and selectivity toward flavanone synthesis through aldol condensation and subsequent intramolecular Michael addition of benzaldehyde and 2'-hydroxyacetophenone, was synthesized for the first time via co-condensation of tetraethylorthosilicate (TEOS) and 3-aminopropyltriethoxysilane (APTES) using an amphiphilic block copolymer as the structure-directing agent.

High resolution 31P NMR study of octacalcium phosphate.

We have assigned the (31)P high-resolution spectrum of octacalcium phosphate by (31)P double quantum and HETCOR spectroscopy. The (31)P peaks at -0.2, 2.0, 3.3 and 3.7 ppm are assigned to P5/P6, P3, P2/P4 and P1, respectively. Our data reveal that substantial amount of the PO(4)(3-) groups at the P2 and P4 sites have been transformed to HPO(4)(2-) in our octacalcium phosphate sample.