A new nanostructured and highly COOH‐functionalized hybrid organic–inorganic material has been synthesized by the hydrolysis of oligomeric octahedral silsesquioxane (POSS), which contains eight cyanopropyl groups. The hybrid, elemental building block oligomeric octakis(3‐cyanopropyl)silsesquioxane (CN‐POSS) was synthesized from oligomeric octakis(3‐chloropropyl)silsesquioxane (Cl‐POSS) by an exchange reaction. The formation and nanostructuration of the COOH‐functionalized hybrid material were induced by noncovalent hydrogen bonding between COOH‐POSS units without decomposition of the core. The material has been fully characterized by scanning electron microscopy, FTIR and 1H, 13C, and 29Si solid‐state NMR spectroscopy, X‐ray diffraction, and elemental analysis, which confirm that the POSS core remains intact after each chemical modification step. Thermogravimetric analysis indicates that the organic units are thermally stable up to 200 °C. The activation energy related to the proton conductivity of COOH‐POSS has been evaluated and confirms the presence of strong hydrogen bonds. Finally, the accessibility and adsorption capacity of the COOH groups towards transition metal ions have been demonstrated and underline the potential of these hybrid materials in extraction chemistry.
Heterogeneous single-site catalysts contain spatially isolated, well-defined active sites. This allows not only their easy recovery by solid-liquid separation, but also the detailed active site design like in homogeneous catalysts. Here, heterogeneous Pd(II) single-site catalysts were assembled, based on mesoporous metal oxide-bisphosphonate materials as supports. This new family of hybrid organic-inorganic materials with tunable porosity was further functionalized with thioether ligands containing S,O-binding sites that enhance the activity of Pd(II) for C-H activation reactions. The structures of the resulting Pd(II) single-site catalysts were carefully analyzed via solid-state NMR spectroscopy, via texture analysis by N2 physisorption, infrared spectroscopy, and transmission electron microscopy. Furthermore, the immediate environment of the isolated Pd(II) active sites was studied with X-ray absorption spectroscopy. A clear relationship between thioether ligand surface density and catalyst activity could be established. Significantly higher yields were obtained using highly porous metal oxide-bisphosphonate materials as supports compared to materials with lower porosities, such as conventional metal oxides, indicating that the high surface area facilitates the presence of isolated, well-accessible S,O-supported Pd(II) active sites. A wide scope of model substrates, including industrially relevant arenes, can be converted with high yields by the optimal heterogeneous Pd catalyst. a Reaction conditions: 1a (2.5 mmol), 2a (0.25 mmol), Pd@TiOP-S1 (5 mol % Pd), TBPB (0.25 mmol), and AcOH (0.75 mL) at 100 °C for 2 h. b Reaction yield was measured via GC-FID.
A simple synthesis of a hybrid material with a high content (80%) of ibuprofen was reported. The drug release proceeds via a diffusion mechanism and depends on the pH. This extensive system will open new doors to introduce a large variety of drugs, with high potential for biomedical applications.
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