KIT-5 Structural and Textural Changes in Response to Different Methods of Functionalization with Sulfonic Groups

In this project, KIT-5 materials were effectively functionalized with sulfonic groups introduced by grafting or the co-condensation method and tested as heterogeneous solid acid catalyst. A co-condensation procedure leading to the stable, -SO₃H functionalized KIT-5 materials was successfully established. Moreover, the influence of both synthesis methods on the structural and textural parameters, as well as surface chemistry, morphology, and catalytic activity of -SO₃H/KIT-5 materials was thoroughly investigated. The syntheses with 3-mepkaptopropyltrimethoxysilane (MPTMS) acting as a modifying agent resulted in samples in which functional groups were introduced into the structure and/or onto the mesoporous silica surface. The oxidation stage of -SH to -SO₃H groups was carried out under mild conditions, using a "green" oxidant (H₂O₂). The application of different functionalization techniques and the introduction of different amounts of modifying agent allowed for an evaluation of the influence of these parameters on the ordering of the mesoporous structure of KIT-5 materials. The applied methods of assessment of the physicochemical parameters (XRD, low-temperature N₂ sorption, TEM) showed that, especially when the co-condensation method was applied, as the number of functional groups increased, the ordering of structure characteristic of KIT-5 decreased. On the other hand, the samples modified by grafting had a stable structure, regardless of the amount of introduced MPTMS. Test reactions carried out on the basis of Friedel-Crafts alkylation process showed that the synthesized materials can be considered promising acid catalysts in heterogeneous catalysis reactions.

Creation of discrete active site domains via mesoporous silica poly(styrene) composite materials for incompatible acid–base cascade reactions

Mesoporous silica/polymer hybrid materials catalyze a two-step acid and base cascade reaction. Catalyst design emphasizes compartmentalization of incompatible Lewis base and Brønsted acid catalysts by tuning polymer chain length and silica pore diameter.meter.

Efficient Synthesis of Structured Phospholipids Containing Short-Chain Fatty Acids over a Sulfonated Zn-SBA-15 Catalyst

Catalytic production of structured phospholipids (SPLs) containing short-chain fatty acids (SCFAs) in an efficient heterogeneous manner is of great importance from the standpoint of food engineering. Herein, a bifunctionalized sulfonated Zn-SBA-15 catalyst was studied for SPL synthesis through interesterification of soybean lecithin with ethyl propionate or methyl butyrate. Various characterization techniques such as pyridine Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and ultraviolet-visible diffuse reflectance spectroscopy were conducted to determine the physicochemical properties, so as to build the possible structure-reactivity relationship of the catalyst. In screening tests with commercial Amberlyst-15 or other SBA-15-type materials, the as-prepared sample showed promising catalytic performance probably owing to its mesoporous structure and cooperative role of Brönsted and Lewis acid sites. Notably, the sample was easily separated and recycled without obvious deactivation. In general, the investigated catalyst was regarded as one of the promising alternatives to otherwise expensive biocatalysts for SCFA-containing SPL production.

Tetracycline@silver ions-functionalized mesoporous silica for high bactericidal activity at ultra-low concentration

Aim: Polyether pores were designed and tetracycline-loaded mesoporous silica materials, with their surface decorated by silver ions, were prepared, with the aim of reaching high antibacterial activity. Meanwhile, mammalian cell cytotoxicity and hemolytic effects were not observed using material concentrations tenfold the ones optimized for the bactericidal tests. Methods: Pore size was tuned by changing the polyether content and the surface was covalently decorated with silver thiolate groups. Results: We showed that the biological activity was enhanced by modulating silver ions and tetracycline releases by tuning silver thiolate group concentration on the silica surface and/or by modulating the pH of the environment. Conclusion: The combined use of tetracycline and silver ions with the mesoporous drug-delivery carrier was a very effective strategy against susceptible and tetracycline-resistant Escherichia coli bacteria.

Current advances in the utility of functionalized SBA mesoporous silica for developing encapsulated nanocatalysts: state of the art

The cavities of SBA mesoporous silica materials can be used as nanoreactors for embedding catalytic species such as nanoparticles, complexes and heteropolyacids etc.