Chemistry, porous, organically modified

Chemistry and Properties of Porous, Organically Modified Silica... 

The development of catalysts for the oxidation of organic compounds by air under ambient conditions is of both academic and practical importance (1). Formaldehyde is an important intermediate in synthetic chemistry as well as one of the major pollutants in the human environment (2). While high temperature (> 120 °C) catalytic oxidations are well known (3), low temperature aerobic oxidations under mild conditions have yet to be reported. Polyoxometalates (POMs) are attractive oxidation catalysts because these extensively modifiable metal oxide-like structures have high thermal and hydrolytic stability, tunable acid and redox properties, solubility in various media, etc. (4). Moreover, they can be deposited on fabrics and porous materials to render these materials catalytically decontaminating (5). Here we report the aerobic oxidation of formaldehyde in water under mild conditions (20-40 °C, 1 atm of air or 02) in the presence of Ce-substituted POMs (Ce-POMs). 

Up until 1977, the non-covalent polymeric assemblies found in biological membranes rarely attracted any interest in supramolecular organic chemistry. Pure phospholipids and glycolipids were only synthesized for biophysical chemists who required pure preparations of uniform vesicles, in order to investigate phase transitions, membrane stability and leakiness, and some other physical properties. Only very few attempts were made to deviate from natural membrane lipids and to develop defined artificial membrane systems. In 1977, T. Kunitake published a paper on A Totally Synthetic Bilayer Membrane in which didodecyl dimethylammonium bromide was shown to form stable vesicles. This opened the way to simple and modifiable membrane structures. Since then, organic chemists have prepared numerous monolayer and bilayer membrane structures with hitherto unknown properties and coupled them with redox-active dyes, porous domains and chiral surfaces. Recently, fluid bilayers found in spherical vesicles have also been complemented by crystalline mono-... 

The chemistry and surface properties of porous and non-porous silica were extensively reviewed [8,9]. We have organized this review in several sections starting with a very brief account of mesoporous solids synthesis and their main structural characteristics (see the section on Mesoporous SUica ). This section also comments on the preparation of chemically modified solids and their properties as well as how the mesoporous structure can be controlled. We also present some theoretical results obtained through computer simulations. Those smdies model the sohd structure of sdica that will be employed in other simulations. Section 111 is devoted to the... 

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