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Scheme 3. Oxidation of HMF to 2,5-Furandicarboxylic Acid (FDCA) a a Intermediates: 5-hydroxymethylfuran-2-carboxylic acid (HMFCA), 2,5-diformylfuran (DFF), and 5-formylfuran-2-carboxylic acid (FFCA).

Aerogels are fine inorganic superstructures with enormously high porosity and are known to be exceptional materials with a variety of applications, for example in the area of catalysis. [1] The chemistry of the aerogel synthesis originated from the pioneering work [2] from the early 1930s and was further developed starting from the 1960s. [1,3] Attractive catalytic, thermoresistant, piezoelectric, antiseptic, and many other properties of the aerogels originate from the unique combination of the specific properties of nanomaterials magnified by macroscale self-assembly. Currently, the most investigated materials that form fine aerogel superstructures are silica and other metal oxides together with their mixtures. Recently, the possibility of creating aerogels and even light-emitting monoliths with densities 500 times less than their bulk counterparts from colloidal quantum dots and clusters of metal chalcogenides has attracted attention. These developments may open opportunities in areas such as semiconductor technology, photocatalysis, optoelectronics, and photonics. [4][5][6][7][8][9][10][11][12][13] Quite a number of different approaches have focused on modifying oxide-based aerogels (silica, titania, alumina, etc.) with metal nanoparticles (such as of platinum) to carry the catalytic properties from the metal [14,15] into the porous structures of the aerogels. [1,16,17] Fine mesoporous assemblies of catalytically active metal nanoparticles were also created by using artificial opals [18] and fungi [19] as templates. Other superstructural materials derived from metal nanoparticles include mesoporous platinum-carbon composites, [20] gold nanoparticles interlinked with dithiols, [21] necklace nanochains of hybrid palladium-lipid nanospheres, [22] electrocatalytically active nanoporous platinum aggregates, [23] foams, [24] and highly ordered two-and three-dimensional supercrystals. [25][26][27][28][29] The creation of non-supported metal aerogels has however not been reported to date. Recently, the formation of highly porous spherical aggregates ("supraspheres") of several hundred nanometers in diameter, where nanoparticles from one or two different metals were cross-linked with dithiols, was reported. [30,31] The metal aerogels presented herein exhibit an average density two orders of magnitude lower than that of the reported foams.[32] Their primary structural units match the size range of single nanoparticles (5-20 nm), which is an order of magnitude smaller than that of the self-assembled supraspheres.[31] Moreover, in the present case, no chemical cross-linkers are involved in the self-assembly process. The formation of such noble-metal nanoparticle-based mesoporous monometallic and bimetallic aerogels is an important step towards self-supported monoliths with enormously high catalytically active surfaces. Considering that metal nanoparticles possess very specific optical properties owing to their pronounced surface plasmon resonance, aerogels from metal nanoparticles may also find future applications in nano...

Microporous carbons, produced by selective etching of metal carbides in a chlorine-containing environment, offer narrow distribution of micropores and one of the highest specific capacitances reported when used in electrical double layer capacitors (EDLC) with organic electrolytes. Previously, the small micropores in these carbons served as an impediment to ion transport and limited the power storage characteristics of EDLC. Here we demonstrate, for the first time, how the preparation and application of templated carbide-derived carbon (CDC) can overcome the present limitations and show the route for dramatic performance enhancement. The ordered mesoporous channels in the produced CDC serve as ion-highways and allow for very fast ionic transport into the bulk of the CDC particles. The enhanced transport led to 85% capacitance retention at current densities up to approximately 20 A/g. The ordered mesopores in silicon carbide precursor also allow the produced CDC to exhibit a specific surface area up to 2430 m(2)/g and a specific capacitance up to 170 F/g when tested in 1 M tetraethylammonium tetrafluoroborate solution in acetonitrile, nearly doubling the previously reported values.

Isosorbide is a platform chemical of considerable importance for the future replacement of fossil resource-based products. Applications as monomers and building blocks for new polymers and functional materials, new organic solvents, for medical and pharmaceutical applications, and even as fuels or fuel additives are conceivable. The conversion of isosorbide to valuable derivatives by functionalization or substitution of the hydroxyl groups is difficult because of the different configurations of the 2- and 5-positions and the resulting different reactivity and steric hindrance of the two hydroxyl groups. Although a substantial amount of work has been published using exclusively the endo or exo derivatives isomannide and isoidide, respectively, as starting material, a considerable effort is still necessary to transfer and adapt these methods for the efficient conversion of isosorbide. This Minireview deals with all aspects of isosorbide chemistry, which includes its production by catalytic processes, special properties, and chemical transformations for its utilization in biogenic polymers and other applications of interest.