Inst. Chemie

687 Items

Recent Submissions
Speciation of molybdenum- and vanadium-based polyoxometalate species in aqueous medium and gas-phase and its consequences for M1 structured MoV oxide synthesis

Jung, Sabrina (2018)

Polyoxomolybdate and –vanadate speciation has been examined in aqueous solution and in the gas-phase depending on the concentration and pH value. Raman and UV-vis spectroscopy showed the compact and highly charged hepta- and octamolybdate, and decavanadate species to be present, respectively, while mass spectrometric measurements led to a multitude of different species. The structure of these g...

Computational chemistry studies on metallo-enzymes for the splitting of hydrogen and the interconversion between carbon monoxide and carbon dioxide

Tombolelli, Daria (2018)

Carbon monoxide dehydrogenases (CODH) are metallo-enzymes which perform the interconversion between CO and CO2. In particular, in the present work, nickel iron containing CODH from Carboxydothermus hydrogenoformans, is studied. Its catalytic mechanism is still unclear, because of the difficulties at the experimental level to trap substrate-bound intermediates and pure redox states. For this rea...

N-heterocyclic silylenes as tools in coordination chemistry and catalysis

Zhou, Yu-Peng (2018)

Low-valent main-group chemistry, especially the chemistry of N-heterocyclic silylenes (NHSis), is one of the most attractive research topics in contemporary organometallic chemistry. In this dissertation, a series of NHSis and their derivatives were developed and used as ligands to stabilize low-valent germanium compounds as well as in transition metal-mediated homogenous catalysis. The synthe...

Comprehensive snake venomics of the Okinawa Habu pit viper, Protobothrops flavoviridis, by complementary mass spectrometry-guided approaches

Damm, Maik ; Hempel, Benjamin-Florian ; Nalbantsoy, Ayse ; Süßmuth, Roderich D. (2018-07-29)

The Asian world is home to a multitude of venomous and dangerous snakes, which are used to induce various medical effects in the preparation of traditional snake tinctures and alcoholics, like the Japanese snake wine, named Habushu. The aim of this work was to perform the first quantitative proteomic analysis of the Protobothrops flavoviridis pit viper venom. Accordingly, the venom was analyzed...

BiVO4-based photoanodes for photoelectrochemical water splitting

Rohloff, Martin (2018)

Global warming refers to the rise in average surface temperatures on Earth and is considered as the major environmental problem humanity is facing today. An overwhelming scientific consensus maintains that climate change is primarily caused by the combustion of fossil fuels, which releases carbon dioxide and other greenhouse gases into the atmosphere. Consequently, this gives rise to a range of...

Grazing incidence X-ray diffraction

Scherzer, Michael (2018)

The interest to study iridium electrocatalysts originates from their use in PEM electrolyzers, which are used to produce hydrogen from water splitting. The need to overcome the exploitation of fossil fuels and to promote the use of sustainable resources makes this a promising alternative. Usage of expensive and rare iridium additionally pushes research to find cost efficient alternatives, proba...

Surface plasmon resonance based sensor for the detection of glycopeptide antibiotics in milk using rationally designed nanoMIPs

Altintas, Zeynep (2017-07-25)

Glycopeptide antibiotics are known as the last resort for the treatment of serious infections caused by Gram-positive bacteria. The use of milk products contaminated with these antibiotic residues leads to allergic reactions and sensitivity in human. Also, long-term consumption of milk products containing low levels of these antibiotics may cause the relevant bacteria to build up resistance to ...

Frustrated Lewis pairs embedded into microporous polymer networks

Trunk, Matthias Georg (2018)

Aufgrund ihrer vielseitigen potentiellen Anwendungsmöglichkeiten in Gasspeicherung und –trennung, Sensorik und Katalyse haben mikroporöse organische Materialien innerhalb der letzten 20 Jahre eine rasante Entwicklung erfahren. Neben geordneten Materialien wie metall-organischen Gerüstmaterialien (MOFs) und kovalent organischen Gerüstmaterialien (COFs) haben sich mikroporöse Polymernetzwerke (MP...

Property-performance correlations in the oxidative coupling of methane

Wang, Huan (2018)

The oxidative coupling of methane is a “dream reaction” in heterogeneous catalysis to achieve direct conversion for natural gas towards value-added and easily transportable C2 products with high economic relevance. Although extensive academic papers and patents have been reported over the last three decades, no economically viable industrial-scale application is yet achieved because of the limi...

Enzymes as modular catalysts for redox halfreactions in H2-powered chemical synthesis: from biology to technology

Reeve, Holly A. ; Ash, Philip A. ; Park, HyunSeo ; Huang, Ailun ; Posidias, Michalis ; Tomlinson, Chloe ; Lenz, Oliver ; Vincent, Kylie A. (2017-01-06)

The present study considers the ways in which redox enzyme modules are coupled in living cells for linking reductive and oxidative half-reactions, and then reviews examples in which this concept can be exploited technologically in applications of coupled enzyme pairs. We discuss many examples in which enzymes are interfaced with electronically conductive particles to build up heterogeneous cata...

Facile Control over the Supramolecular Ordering of Selfassembled Peptide Scaffolds by Simultaneous Assembly with a Polysacharride

Li, Rui ; Boyd-Moss, Mitchell ; Long, Benjamin ; Martel, Anne ; Parnell, Andrew ; Dennison, Andrew J. C. ; Barrow, Colin J. ; Nisbet, David R. ; Williams, Richard J. (2017-07-06)

Enabling control over macromolecular ordering and the spatial distribution of structures formed via the mechanisms of molecular self-assembly is a challenge that could yield a range of new functional materials. In particular, using the self-assembly of minimalist peptides, to drive the incorporation of large complex molecules will allow a functionalization strategy for the next generation of bi...

Enantioselektive Reduktionen mit Ru–S-Komplexen und Untersuchung der zugrundeliegenden Mechanismen

Bähr, Susanne (2018)

Die vorliegende Dissertation widmet sich der Synthese und Charakterisierung chiraler, kationischer Ruthenium(II)-Thiolatkomplexe und deren Anwendung in enantioselektiven Reduktionen. Die Aufklärung der Mechanismen dieser katalytischen Umsetzungen ist ein weiterer Schwerpunkt. Der erste Teil der Arbeit besteht in der mechanistischen Aufklärung der zuvor entwickelten 1,4-Hydrosilylierung von Py...

Investigating the trimethylaluminium/water ALD process on mesoporous silica by in situ gravimetric monitoring

Strempel, Verena E. ; Knemeyer, Kristian ; Naumann d’Alnoncourt, Raoul ; Rosowski, Frank (2018-05-24)

A low amount of AlOx was successfully deposited on an unordered, mesoporous SiO2 powder using 1–3 ALD (Atomic Layer Deposition) cycles of trimethylaluminium and water. The process was realized in a self-built ALD setup featuring a microbalanceand a fixed particle bed. The reactor temperature was varied between 75, 120, and 200 °C. The self-limiting nature of the deposition was verified by in si...

Higher alcohol synthesis over Rh catalysts: conditioning of Rh/N-CNTs by Co and Mn entrapped in the support

Xie, Zailai ; Frank, Benjamin ; Huang, Xing ; Schlögl, Robert ; Trunschke, Annette (2016-10-13)

Rh nanoparticles supported on commercial non-purified N-doped CNTs (NCNTs) containing residual CNT growth catalyst have been studied in hydrogenation of CO to higher alcohols. It has been found that Co and Mn residues in NCNTs are not inert, but change the catalyst under reaction conditions and efficiently promote the catalyst resulting in both increasing activity and selectivity to C2+ alcohol...

A small-angle neutron scattering environment for in-situ observation of chemical processes

Hayward, Dominic W. ; Chiappisi, Leonardo ; Prévost, Sylvain ; Schweins, Ralf ; Gradzielski, Michael (2018-05-08)

A new sample environment for the observation of ongoing chemical reactions is introduced for small-angle neutron scattering (SANS) experiments which enables structural changes to be followed continuously across a wide Q-range in response to changes in the chemical environment. The approach is demonstrated and validated by performing single and multiple potentiometric titrations on an aqueous an...

Photo- and thermo-responsive poly (ethylene glycol)-based biomaterials

Rahman, Rahima (2018)

Chemically incorporated azobenzenes (AZO) with in a matrix can generate multi-responsive materials that exhibit both temperature and light responsivity; hence act as multi-responsive system. The main aim of the work presented here was to design novel multi-responsive gels having chemically crosslinked azobenzene moiety incorporated into Poly (Ethylene Glycol) (PEG) matrix. The chemically bonded...

Low frequency dynamics of the nitrogenase MoFe protein via femtosecond pump probe spectroscopy

Maiuri, Margherita ; Delfino, Ines ; Cerullo, Giulio ; Manzoni, Cristian ; Pelmenschikov, Vladimir ; Guo, Yisong ; Wang, Hongxin ; Gee, Leland B. ; Dapper, Christie H. ; Newton, William E. ; Cramer, Stephen P. (2015)

We have used femtosecond pump-probe spectroscopy (FPPS) to study the FeMo-cofactor within the nitrogenase (N2ase) MoFe protein from Azotobacter vinelandii. A sub-20-fs visible laser pulse was used to pump the sample to an excited electronic state, and a second sub-10-fs pulse was used to probe changes in transmission as a function of probe wavelength and delay time. The excited protein relaxes ...

Dendronylation: Residue-specific chemoselective attachment of oligoglycerol dendrimers on proteins with noncanonical amino acids

Ma, Ying ; Thota, Bala N. S. ; Haag, Rainer ; Budisa, Nediljko (2015)

Polyglycerol dendrimers as an important class of polymeric materials especially attractive for covalent attachment to therapeutic proteins as a useful alternative to traditional PEGylation procedures. Herein, we combine in vivo noncanonical amino acid (ncAA) incorporation and chemoselective conjugation in vitro to produce novel hybrid protein–dendrimer conjugates with the defined architectures....

Spectroelectrochemical study of biomolecules in artificial membrane systems

Gonzalez, Barbara Daiana (2018)

This work presents a spectroeletrochemical approach combining electrochemical impedance spectroscopy (EIS) and surface-enhanced infrared absorption (SEIRA) spectroscopy to characterise the interaction of proteins and peptides with model membranes. The artificial membrane systems are assembled on a nanostructured Au-film, which is deposited on an attenuated total reflectance (ATR) crystal as a p...

Synthese von hochoberflächigen Metalloxiden und geträgerten Metalloxid-Katalysatoren für die oxidative Kupplung von Methan

Klapproth, Miriam (2018)

Methane, which is the main component of biogas and natural gas, is traded as one of the future alternative raw materials to petroleum. To date, methane is mainly used as fuel for energy generation. A further indirect application is the synthesis of high-quality hydrocarbons via the complex synthesis of syngas, which can be synthesized of methane. In comparison to indirect transformations, direc...