@misc{KoenigKellingSchildeetal.2017,
  author    = {K{\"o}nig, Jana and Kelling, Alexandra and Schilde, Uwe and Strauch, Peter},
  title     = {[µ2-O,O′,Oʺ,Oʺ′-Bis(1,2-dithiooxalato-S,S′)nickel(II)]bis[-O,O′-bis(1,2-dithiooxalato-S,S′)-nickel(II)pentaquaholmium(III)]hydrate, [Ho2Ni3(dto)6(H2O)10]},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-400598},
  pages     = {5},
  year      = {2017},
  abstract  = {Planar bis(1,2-dithiooxalato)nickelate(II), [Ni(dto)]2- reacts in aqueous solutions with lanthanide ions (Ln3+) to form pentanuclear, hetero-bimetallic complexes of the general composition [{Ln(H2O)n}2{Ni(dto)2}3]·xH2O. (n = 4 or 5; x = 9-12). The complex [{Ho(H2O)5}2{Ni(dto)2}3]·10H2O, Ho2Ni3, was synthesized and characterized by single crystal X-ray structure analysis and powder diffraction. The Ho2Ni3 complex crystallizes as monoclinic crystals in the space group P21/c. The channels and cavities, appearing in the crystal packing of the complex molecules, are occupied by a varying amount of non-coordinated water molecules.},
  language  = {en}
}
@misc{HardyTorresRendonLealEganaetal.2017,
  author    = {Hardy, John G. and Torres-Rendon, Jose Guillermo and Leal-Ega{\~n}a, Aldo and Walther, Andreas and Schlaad, Helmut and C{\"o}lfen, Helmut and Scheibel, Thomas R.},
  title     = {Biomineralization of engineered spider silk protein-based composite materials for bone tissue engineering},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-400519},
  pages     = {13},
  year      = {2017},
  abstract  = {Materials based on biodegradable polyesters, such as poly(butylene terephthalate) (PBT) or poly(butylene terephthalate-co-poly(alkylene glycol) terephthalate) (PBTAT), have potential application as pro-regenerative scaffolds for bone tissue engineering. Herein, the preparation of films composed of PBT or PBTAT and an engineered spider silk protein, (eADF4(C16)), that displays multiple carboxylic acid moieties capable of binding calcium ions and facilitating their biomineralization with calcium carbonate or calcium phosphate is reported. Human mesenchymal stem cells cultured on films mineralized with calcium phosphate show enhanced levels of alkaline phosphatase activity suggesting that such composites have potential use for bone tissue engineering.},
  language  = {en}
}
@misc{SchildePazOrtiz2017,
  author    = {Schilde, Uwe and Paz, Christian and Ortiz, Leandro},
  title     = {Crystal structure of erioflorin isolated from Podanthus mitiqui (L.)},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-401832},
  pages     = {4},
  year      = {2017},
  abstract  = {The title compound, erioflorin, C19H24O6 [systematic name: (1aR,3S,4Z,5aR,8aR,9R,10aR)-1a, 2,3,5a, 7,8,8a, 9,10,10a-decahydro-3-hydroxy-4,10a-dimethyl-8-methylidene-7-oxooxireno[5,6] cyclodeca[1,2-b]furan-9-yl methacrylate], is a tricyclic germacrane sesquiterpene lactone, which was isolated from Podanthus mitiqui (L.). The compound crystallizes in the space group P2(1)2(1)2(1), and its molecular structure consists of a methacrylic ester of a ten-membered ring sesquiterpenoid annelated with an epoxide and a butyrolactone. The structure is stabilized by one intramolecular C-H center dot center dot center dot O hydrogen bond. An O-H center dot center dot center dot O hydrogen bond and further C-H center dot center dot center dot O interactions can be observed in the packing.},
  language  = {en}
}
@phdthesis{Jordan2017,
  author    = {Jordan, Thomas},
  title     = {CxNy-materials from supramolecular precursors for "All-Carbon" composite materials},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-398855},
  school      = {Universit{\"a}t Potsdam},
  pages     = {157},
  year      = {2017},
  abstract  = {Among modern functional materials, the class of nitrogen-containing carbons combines non-toxicity and sustainability with outstanding properties. The versatility of this materials class is based on the opportunity to tune electronic and catalytic properties via the nitrogen content and -motifs: This ranges from the electronically conducting N-doped carbon, where few carbon atoms in the graphitic lattice are substituted by nitrogen, to the organic semiconductor graphitic carbon nitride (g-C₃N₄), with a structure based on tri-s-triazine units. In general, composites can reveal outstanding catalytic properties due to synergistic behavior, e.g. the formation of electronic heterojunctions. In this thesis, the formation of an "all-carbon" heterojunction was targeted, i.e. differences in the electronic properties of the single components were achieved by the introduction of different nitrogen motives into the carbon lattice. Such composites are promising as metal-free catalysts for the photocatalytic water splitting. Here, hydrogen can be generated from water by light irradiation with the use of a photocatalyst. As first part of the heterojunction, the organic semiconductor g-C₃N₄ was employed, because of its suitable band structure for photocatalytic water splitting, high stability and non-toxicity. The second part was chosen as C₂N, a recently discovered semiconductor. Compared to g-C₃N₄, the less nitrogen containing C₂N has a smaller band gap and a higher absorption coefficient in the visible light range, which is expected to increase the optical absorption in the composite eventually leading to an enhanced charge carrier separation due to the formation of an electronic heterojunction. The aim of preparing an "all-carbon" composite included the research on appropriate precursors for the respective components g-C₃N₄ and C₂N, as well as strategies for appropriate structuring. This was targeted by applying precursors which can form supramolecular pre-organized structures. This allows for more control over morphology and atom patterns during the carbonization process. In the first part of this thesis, it was demonstrated how the photocatalytic activity of g-C₃N₄ can be increased by the targeted introduction of defects or surface terminations. This was achieved by using caffeine as a "growth stopping" additive during the formation of the hydrogen-bonded supramolecular precursor complexes. The increased photocatalytic activity of the obtained materials was demonstrated with dye degradation experiments. The second part of this thesis was focused on the synthesis of the second component C₂N. Here, a deep eutectic mixture from hexaketocyclohexane and urea was structured using the biopolymer chitosan. This scaffolding resulted in mesoporous nitrogen-doped carbon monoliths and beads. CO₂- and dye-adsorption experiments with the obtained monolith material revealed a high isosteric heat of CO₂-adsorption and showed the accessibility of the monolithic pore system to larger dye molecules. Furthermore, a novel precursor system for C₂N was explored, based on organic crystals from squaric acid and urea. The respective C₂N carbon with an unusual sheet-like morphology could be synthesized by carbonization of the crystals at 550 °C. With this precursor system, also microporous C₂N carbon with a BET surface area of 865 m²/g was obtained by "salt-templating" with ZnCl₂. Finally, the preparation of a g-C₃N₄/C₂N "all carbon" composite heterojunction was attempted by the self-assembly of g-C₃N₄ and C₂N nanosheets and tested for photocatalytic water splitting. Indeed, the composites revealed high rates of hydrogen evolution when compared to bulk g-C₃N₄. However, the increased catalytic activity was mainly attributed to the high surface area of the nanocomposites rather than to the composition. With regard to alternative composite synthesis ways, first experiments indicated N-Methyl-2-pyrrolidon to be suitable for higher concentrated dispersion of C₂N nanosheets. Eventually, the results obtained in this thesis provide precious synthetic contributions towards the preparation and processing of carbon/nitrogen compounds for energy applications.},
  language  = {en}
}
@phdthesis{Meiling2017,
  author    = {Meiling, Till Thomas},
  title     = {Development of a reliable and environmentally friendly synthesis for fluorescence carbon nanodots},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-410160},
  school      = {Universit{\"a}t Potsdam},
  pages     = {198},
  year      = {2017},
  abstract  = {Carbon nanodots (CNDs) have generated considerable attention due to their promising properties, e.g. high water solubility, chemical inertness, resistance to photobleaching, high biocompatibility and ease of functionalization. These properties render them ideal for a wide range of functions, e.g. electrochemical applications, waste water treatment, (photo)catalysis, bio-imaging and bio-technology, as well as chemical sensing, and optoelectronic devices like LEDs. In particular, the ability to prepare CNDs from a wide range of accessible organic materials makes them a potential alternative for conventional organic dyes and semiconductor quantum dots (QDs) in various applications. However, current synthesis methods are typically expensive and depend on complex and time-consuming processes or severe synthesis conditions and toxic chemicals. One way to reduce overall preparation costs is the use of biological waste as starting material. Hence, natural carbon sources such as pomelo peal, egg white and egg yolk, orange juice, and even eggshells, to name a few; have been used for the preparation of CNDs. While the use of waste is desirable, especially to avoid competition with essential food production, most starting-materials lack the essential purity and structural homogeneity to obtain homogeneous carbon dots. Furthermore, most synthesis approaches reported to date require extensive purification steps and have resulted in carbon dots with heterogeneous photoluminescent properties and indefinite composition. For this reason, among others, the relationship between CND structure (e.g. size, edge shape, functional groups and overall composition) and photophysical properties is yet not fully understood. This is particularly true for carbon dots displaying selective luminescence (one of their most intriguing properties), i.e. their PL emission wavelength can be tuned by varying the excitation wavelength. In this work, a new reliable, economic, and environmentally-friendly one-step synthesis is established to obtain CNDs with well-defined and reproducible photoluminescence (PL) properties via the microwave-assisted hydrothermal treatment of starch, carboxylic acids and Tris-EDTA (TE) buffer as carbon- and nitrogen source, respectively. The presented microwave-assisted hydrothermal precursor carbonization (MW-hPC) is characterized by its cost-efficiency, simplicity, short reaction times, low environmental footprint, and high yields of approx. 80\% (w/w). Furthermore, only a single synthesis step is necessary to obtain homogeneous water-soluble CNDs with no need for further purification. Depending on starting materials and reaction conditions different types of CNDs have been prepared. The as-prepared CNDs exhibit reproducible, highly homogeneous and favourable PL properties with narrow emission bands (approx. 70nm FWHM), are non-blinking, and are ready to use without need for further purification, modification or surface passivation agents. Furthermore, the CNDs are comparatively small (approx. 2.0nm to 2.4nm) with narrow size distributions; are stable over a long period of time (at least one year), either in solution or as a dried solid; and maintain their PL properties when re-dispersed in solution. Depending on CND type, the PL quantum yield (PLQY) can be adjusted from as low as 1\% to as high as 90\%; one of the highest reported PLQY values (for CNDs) so far. An essential part of this work was the utilization of a microwave synthesis reactor, allowing various batch sizes and precise control over reaction temperature and -time, pressure, and heating- and cooling rate, while also being safe to operate at elevated reaction conditions (e.g. 230 ±C and 30 bar). The hereby-achieved high sample throughput allowed, for the first time, the thorough investigation of a wide range of synthesis parameters, providing valuable insight into the CND formation. The influence of carbon- and nitrogen source, precursor concentration and -combination, reaction time and -temperature, batch size, and post-synthesis purification steps were carefully investigated regarding their influence on the optical properties of as-synthesized CNDs. In addition, the change in photophysical properties resulting from the conversion of CND solution into solid and back into the solution was investigated. Remarkably, upon freeze-drying the initial brown CND-solution turns into a non-fluorescent white/slightly yellow to brown solid which recovers PL in aqueous solution. Selected CND samples were also subject to EDX, FTIR, NMR, PL lifetime (TCSPC), particle size (TEM), TGA and XRD analysis. Besides structural characterization, the pH- and excitation dependent PL characteristics (i.e. selective luminescence) were examined; giving inside into the origin of photophysical properties and excitation dependent behaviour of CNDs. The obtained results support the notion that for CNDs the nature of the surface states determines the PL properties and that excitation dependent behaviour is caused by the "Giant Red-Edge Excitation Shift" (GREES).},
  language  = {en}
}
@phdthesis{Dippel2017,
  author    = {Dippel, Sandor},
  title     = {Development of functional hydrogels for sensor applications},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-398252},
  school      = {Universit{\"a}t Potsdam},
  pages     = {127},
  year      = {2017},
  abstract  = {In this work, a sensor system based on thermoresponsive materials is developed by utilizing a modular approach. By synthesizing three different key monomers containing either a carboxyl, alkene or alkyne end group connected with a spacer to the methacrylic polymerizable unit, a flexible copolymerization strategy has been set up with oligo ethylene glycol methacrylates. This allows to tune the lower critical solution temperature (LCST) of the polymers in aqueous media. The molar masses are variable thanks to the excurse taken in polymerization in ionic liquids thus stretching molar masses from 25 to over 1000 kDa. The systems that were shown shown to be effective in aqueous solution could be immobilized on surfaces by copolymerizing photo crosslinkable units. The immobilized systems were formulated to give different layer thicknesses, swelling ratios and mesh sizes depending on the demand of the coupling reaction. The coupling of detector units or model molecules is approached via reactions of the click chemistry pool, and the reactions are evaluated on their efficiency under those aspects, too. These coupling reactions are followed by surface plasmon resonance spectroscopy (SPR) to judge efficiency. With these tools at hand, Salmonella saccharides could be selectively detected by SPR. Influenza viruses were detected in solution by turbidimetry in solution as well as by a copolymerized solvatochromic dye to track binding via the changes of the polymers' fluorescence by said binding event. This effect could also be achieved by utilizing the thermoresponsive behavior. Another demonstrator consists of the detection system bound to a quartz surface, thus allowing the virus detection on a solid carrier. The experiments show the great potential of combining the concepts of thermoresponsive materials and click chemistry to develop technically simple sensors for large biomolecules and viruses.},
  language  = {en}
}
@phdthesis{MbayaMani2017,
  author    = {Mbaya Mani, Christian},
  title     = {Functional nanoporous carbon-based materials derived from oxocarbon-metal coordination complexes},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-407866},
  school      = {Universit{\"a}t Potsdam},
  pages     = {IV, 135},
  year      = {2017},
  abstract  = {Nanoporous carbon based materials are of particular interest for both science and industry due to their exceptional properties such as a large surface area, high pore volume, high electroconductivity as well as high chemical and thermal stability. Benefiting from these advantageous properties, nanoporous carbons proved to be useful in various energy and environment related applications including energy storage and conversion, catalysis, gas sorption and separation technologies. The synthesis of nanoporous carbons classically involves thermal carbonization of the carbon precursors (e.g. phenolic resins, polyacrylonitrile, poly(vinyl alcohol) etc.) followed by an activation step and/or it makes use of classical hard or soft templates to obtain well-defined porous structures. However, these synthesis strategies are complicated and costly; and make use of hazardous chemicals, hindering their application for large-scale production. Furthermore, control over the carbon materials properties is challenging owing to the relatively unpredictable processes at the high carbonization temperatures. In the present thesis, nanoporous carbon based materials are prepared by the direct heat treatment of crystalline precursor materials with pre-defined properties. This synthesis strategy does not require any additional carbon sources or classical hard- or soft templates. The highly stable and porous crystalline precursors are based on coordination compounds of the squarate and croconate ions with various divalent metal ions including Zn2+, Cu2+, Ni2+, and Co2+, respectively. Here, the structural properties of the crystals can be controlled by the choice of appropriate synthesis conditions such as the crystal aging temperature, the ligand/metal molar ratio, the metal ion, and the organic ligand system. In this context, the coordination of the squarate ions to Zn2+ yields porous 3D cube crystalline particles. The morphology of the cubes can be tuned from densely packed cubes with a smooth surface to cubes with intriguing micrometer-sized openings and voids which evolve on the centers of the low index faces as the crystal aging temperature is raised. By varying the molar ratio, the particle shape can be changed from truncated cubes to perfect cubes with right-angled edges. These crystalline precursors can be easily transformed into the respective carbon based materials by heat treatment at elevated temperatures in a nitrogen atmosphere followed by a facile washing step. The resulting carbons are obtained in good yields and possess a hierarchical pore structure with well-organized and interconnected micro-, meso- and macropores. Moreover, high surface areas and large pore volumes of up to 1957 m2 g-1 and 2.31 cm3 g-1 are achieved, respectively, whereby the macroscopic structure of the precursors is preserved throughout the whole synthesis procedure. Owing to these advantageous properties, the resulting carbon based materials represent promising supercapacitor electrode materials for energy storage applications. This is exemplarily demonstrated by employing the 3D hierarchical porous carbon cubes derived from squarate-zinc coordination compounds as electrode material showing a specific capacitance of 133 F g-1 in H2SO4 at a scan rate of 5 mV s-1 and retaining 67\% of this specific capacitance when the scan rate is increased to 200 mV s-1. In a further application, the porous carbon cubes derived from squarate-zinc coordination compounds are used as high surface area support material and decorated with nickel nanoparticles via an incipient wetness impregnation. The resulting composite material combines a high surface area, a hierarchical pore structure with high functionality and well-accessible pores. Moreover, owing to their regular micro-cube shape, they allow for a good packing of a fixed-bed flow reactor along with high column efficiency and a minimized pressure drop throughout the packed reactor. Therefore, the composite is employed as heterogeneous catalyst in the selective hydrogenation of 5-hydroxymethylfurfural to 2,5-dimethylfuran showing good catalytic performance and overcoming the conventional problem of column blocking. Thinking about the rational design of 3D carbon geometries, the functions and properties of the resulting carbon-based materials can be further expanded by the rational introduction of heteroatoms (e.g. N, B, S, P, etc.) into the carbon structures in order to alter properties such as wettability, surface polarity as well as the electrochemical landscape. In this context, the use of crystalline materials based on oxocarbon-metal ion complexes can open a platform of highly functional materials for all processes that involve surface processes.},
  language  = {en}
}
@phdthesis{Olejko2017,
  author    = {Olejko, Lydia},
  title     = {F{\"o}rster resonance energy transfer (FRET)-based nanophotonics using DNA origami structures},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-396747},
  school      = {Universit{\"a}t Potsdam},
  year      = {2017},
  abstract  = {The field of nanophotonics focuses on the interaction between electromagnetic radiation and matter on the nanometer scale. The elements of nanoscale photonic devices can transfer excitation energy non-radiatively from an excited donor molecule to an acceptor molecule by F{\"o}rster resonance energy transfer (FRET). The efficiency of this energy transfer is highly dependent on the donor-acceptor distance. Hence, in these nanoscale photonic devices it is of high importance to have a good control over the spatial assembly of used fluorophores. Based on molecular self-assembly processes, various nanostructures can be produced. Here, DNA nanotechnology and especially the DNA origami technique are auspicious self-assembling methods. By using DNA origami nanostructures different fluorophores can be introduced with a high local control to create a variety of nanoscale photonic objects. The applications of such nanostructures range from photonic wires and logic gates for molecular computing to artificial light harvesting systems for artificial photosynthesis. In the present cumulative doctoral thesis, different FRET systems on DNA origami structures have been designed and thoroughly analyzed. Firstly, the formation of guanine (G) quadruplex structures from G rich DNA sequences has been studied based on a two-color FRET system (Fluorescein (FAM)/Cyanine3 (Cy3)). Here, the influences of different cations (Na+ and K+), of the DNA origami structure and of the DNA sequence on the G-quadruplex formation have been analyzed. In this study, an ion-selective K+ sensing scheme based on the G-quadruplex formation on DNA origami structures has been developed. Subsequently, the reversibility of the G-quadruplex formation on DNA origami structures has been evaluated. This has been done for the simple two-color FRET system which has then been advanced to a switchable photonic wire by introducing additional fluorophores (FAM/Cy3/Cyanine5 (Cy5)/IRDye®700). In the last part, the emission intensity of the acceptor molecule (Cy5) in a three-color FRET cascade has been tuned by arranging multiple donor (FAM) and transmitter (Cy3) molecules around the central acceptor molecule. In such artificial light harvesting systems, the excitation energy is absorbed by several donor and transmitter molecules followed by an energy transfer to the acceptor leading to a brighter Cy5 emission. Furthermore, the range of possible excitation wavelengths is extended by using several different fluorophores (FAM/Cy3/Cy5). In this part of the thesis, the light harvesting efficiency (antenna effect) and the FRET efficiency of different donor/transmitter/acceptor assemblies have been analyzed and the artificial light harvesting complex has been optimized in this respect.},
  language  = {en}
}
@phdthesis{Heck2017,
  author    = {Heck, Christian},
  title     = {Gold and silver nanolenses self-assembled by DNA origami},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-409002},
  school      = {Universit{\"a}t Potsdam},
  pages     = {ix, 125},
  year      = {2017},
  abstract  = {Nanolenses are linear chains of differently-sized metal nanoparticles, which can theoretically provide extremely high field enhancements. The complex structure renders their synthesis challenging and has hampered closer analyses so far. Here, the technique of DNA origami was used to self-assemble DNA-coated 10 nm, 20 nm, and 60 nm gold or silver nanoparticles into gold or silver nanolenses. Three different geometrical arrangements of gold nanolenses were assembled, and for each of the three, sets of single gold nanolenses were investigated in detail by atomic force microscopy, scanning electron microscopy, dark-field scattering and Raman spectroscopy. The surface-enhanced Raman scattering (SERS) capabilities of the single nanolenses were assessed by labelling the 10 nm gold nanoparticle selectively with dye molecules. The experimental data was complemented by finite-difference time-domain simulations. For those gold nanolenses which showed the strongest field enhancement, SERS signals from the two different internal gaps were compared by selectively placing probe dyes on the 20 nm or 60 nm gold particles. The highest enhancement was found for the gap between the 20 nm and 10 nm nanoparticle, which is indicative of a cascaded field enhancement. The protein streptavidin was labelled with alkyne groups and served as a biological model analyte, bound between the 20 nm and 10 nm particle of silver nanolenses. Thereby, a SERS signal from a single streptavidin could be detected. Background peaks observed in SERS measurements on single silver nanolenses could be attributed to amorphous carbon. It was shown that the amorphous carbon is generated in situ.},
  language  = {en}
}
@phdthesis{Braun2017,
  author    = {Braun, Max},
  title     = {Heterogeneous Catalysis for the Conversion of Fructose to Chemicals and Fuel in a Continuous Flow Process},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-410370},
  school      = {Universit{\"a}t Potsdam},
  pages     = {151},
  year      = {2017},
  abstract  = {Die Umsetzung von Zucker (Kohlenhydrate) in einem kontinuierlichen Prozess er{\"o}ffnet M{\"o}glichkeiten der Synthese diverser Chemikalien und Treibstoff aus erneuerbaren Ressourcen, welche heute {\"u}berwiegend aus fossilen Quellen stammen. Passend zum Konzept der Bioraffinerie und der „gr{\"u}nen Chemie", liegt der Fokus dieser Arbeit auf der Umsetzung von in Ethanol gel{\"o}ster Fruktose in einem kontinuierlichen Verfahren, mit Hilfe eigens entwickelter heterogener Katalysatoren. Die Dehydratisierung von Fruktose wird mit einem heterogenen S{\"a}urekatalysator realisiert, w{\"a}hrend die Folgeprodukte mittels einer Hydrodesoxygenierung umgesetzt werden. F{\"u}r den zweiten Schritt kommen Metallkatalysatoren auf Basis von Nickel und Wolframcarbid (WC) zum Einsatz, wodurch der Einsatz teurer Edelmetalle vermieden werden kann. Hauptprodukte des zweistufigen Verfahrens sind 2,5-Dimethylfuran (DMF) und Ethyllevulinat (EL). Beide Molek{\"u}le sind vielversprechende alternative Treibstoffe, bzw. k{\"o}nnen gebr{\"a}uchlichen Treibstoffen beigemischt werden, um deren Einsatz zu reduzieren und schrittweise zu substituieren. Alternativ k{\"o}nnen die Zwischenprodukte der Dehydratisierung, sowie DMF und EL weiter zu Chemikalien umgesetzt werden, welche in der Polymersynthese, als L{\"o}sungsmittel oder als Grundchemikalien eingesetzt werden k{\"o}nnen. Die Entwicklung der jeweiligen Katalysatoren f{\"u}r Dehydratisierungs- und Hydrodesoxygenierungsreaktionen erfolgt auf Basis von karbonisierter Biomasse, sowie Wolframcarbid. Die jeweiligen Reaktivit{\"a}ten werden durch Standardreaktionen getestet, wobei sich Wolframcarbid in Nanopartikelform, in Kombination mit Wasserstoff als sehr aktiv erwiesen hat. Der selbst entwickelte aktivierte Kohlenstoff, das kommerzielle Amberlyst 15, sowie Wolframcarbid mit zus{\"a}tzlichen Nickel-Nanopartikeln werden f{\"u}r weiterf{\"u}hrende Reaktionen in einem kontinuierlichen Prozess herangezogen und kombiniert. Um den Umsatz von Fruktose zu DMF in einer „zwei Reaktoren Anlage" zu erm{\"o}glichen, wird eine Erweiterung eines kommerziellen Reaktorsystems um einen weiteren Reaktor vorgenommen. Die Verweilzeit in der Reaktoranlage betr{\"a}gt somit ca. 14 Minuten, wobei 11 Minuten auf die erste S{\"a}ule (Dehydratisierung) und 3 Minuten auf die zweite S{\"a}ule (Hydrodesoxygenierung) entfallen. In diesem kontinuierlichen und zweistufigen System lassen sich Ausbeuten von 38.5 \% DMF und 47 \% EL erzielen. Ein kontinuierlicher Lauf von sieben Stunden zeigt die Stabilit{\"a}t der eingesetzten Katalysatoren, auch wenn eine geringe Deaktivierung des Dehydratisierungskatalysators beobachtet werden kann. Der Ni@WC Katalysator zeigte hingegen keine Abnahme der Nickel Konzentration und somit kommt es zu keiner Auswaschung des Metalls. Das gebildete EL wurde hingegen nicht umgesetzt und verbleibt unver{\"a}ndert in L{\"o}sung. Das zweistufige System wurde schließlich in einem Mischkatalysatorsystem kombiniert, wobei auf aktivierten und sulfonierten Kohlenstoff zur{\"u}ckgegriffen wurde. Dieser zeigte bereits eine Transferhydrodesoxygenierungsaktivit{\"a}t. Diese Beobachtung ist deshalb bemerkenswert, da erst seit kurzem bekannt ist, dass Graphenstrukturen an sich katalytisch aktiv sein k{\"o}nnen. Um diese Aktivit{\"a}t weiter zu steigern, wurde der aktivierte Kohlenstoff mit 10 wt\% Ni@WC gemischt, sodass beide Katalysatoren in einer S{\"a}ule vorliegen. Die urspr{\"u}nglichen 2 \% DMF Ausbeute mit reinem aktivierten Kohlenstoff k{\"o}nnen somit auf 12 \% gesteigert werden, da das Folgeprodukt EL hierbei vermieden wird und das Zwischenprodukt „HMF Derivat" direkt zu DMF weiter reagieren kann. Dieses Ergebnis zeigt das Potential der „ein Reaktor Umsetzung", weshalb eine kontinuierliche Durchflussreaktoranlage im Litermaßstab als Scale-Up des vorhergehenden Labormaßstabs realisiert wurde. Der 800 mm x 28.5 mm Reaktor bedient eine maximale Flussrate von 50 mL min-1, Dr{\"u}cke von 100 bar und Temperaturen bis zu 500 °C.},
  language  = {en}
}