Inst. Chemie

679 Items

Recent Submissions
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...

Chemometrische Analysestrategien für Raman-spektroskopische Daten

Keidel, Anke (2018)

Gegenstand dieser Arbeit sind chemometrische Methoden zur Analyse komplexer Datensätze, die mittels Raman-Spektroskopie erzeugt werden. Anhand exemplarischer Problemstellungen werden geeignete Strategien zur Dechiffrierung der chemischen und physikalischen Informationen eines biologischen oder chemischen Systems aus experimentellen Spektren dargestellt und bewertet. Gemeinsames Ziel der verwend...

Response to “Comment on ‘Indications of energetic consequences of decoherence at short times for scattering from open quantum systems’” [AIP Advances 1, 049101 (2011)]

Chatzidimitriou-Dreismann, Chariton Aris ; Gray, E. MacA. ; Blach, T. P. (2011)

The Comment by Mayers and Reiter criticizes our work on two counts. Firstly, it is claimed that the quantum decoherence effects that we report in consequence of our experimental analysis of neutron Compton scattering from H in gaseous H2 are not, as we maintain, outside the framework of conventional neutron scattering theory. Secondly, it is claimed that we did not really observe such effects, ...

Synthesis of an electronically modified carbon nitride from a processable semiconductor, 3-amino-1,2,4-triazole oligomer, via a topotactic-like phase transition

Savateev, Aleksandr ; Pronkin, Sergey ; Epping, Jan Dirk ; Willinger, Marc Georg ; Antonietti, Markus ; Dontsova, Dariya (2017)

A thermally induced topotactic transformation of organic polymeric semiconductors is achieved using similarity of the chemical structures of two C,N,H-containing materials. Namely, the oligomer of 3-amino-1,2,4-triazole (OATA) is transformed into an electronically modified graphitic carbon nitride (OATA-CN) upon heating at 550 °C. During the transition, the flat band potential of the organic se...

Cyclohexa-1,4-dienes in transition-metal-free ionic transfer processes

Keess, Sebastian ; Oestreich, Martin (2017)

Safe- and convenient-to-handle surrogates of hazardous chemicals are always in demand. Recently introduced cyclohexa-1,4-dienes with adequate substitution fulfil this role as El+/H− equivalents in B(C6F5)3-catalysed transfer reactions of El–H to π- and σ-donors (C[double bond, length as m-dash]C/C[triple bond, length as m-dash]C and C[double bond, length as m-dash]O/C[double bond, length as m-d...

Synthesis of a cyclopentadienyl(imino)stannylene and its direct conversion into halo(imino)stannylenes

Ochiai, Tatsumi ; Inoue, Shigeyoshi (2017)

The reaction of stannocene Cp2Sn with iminolithium LiNIPr (NIPr = bis(2,6-diisopropylphenyl)imidazolin-2-iminato) afforded the dimeric cyclopentadienyl(imino)stannylene [(η1-Cp)SnNIPr]2 (1). Compound 1 exhibits unexpected reactivity towards haloalkanes. The high-yield conversion of 1 into chlorostannylene [ClSnNIPr]2 (2) and bromostannylene [BrSnNIPr]2 (3) were accomplished by treatment with di...

Construction of a polyproline structure with hydrophobic exterior using octahydroindole-2-carboxylic acid

Kubyshkin, Vladimir ; Budisa, Nediljko (2016)

The proline analogue (2S,3aS,7aS)-octahydroindole-2-carboxylic acid (Oic) has been previously applied as a proline substitute in pharmocologically active peptides and as a structural component of the antihypertensive drug Perindopril. Herein, we describe the formation of an oligoproline structure by an Oic oligomer. A series of Oic oligomers were investigated to show the structural and energeti...

PNIPAM microgels in external fields

Backes, Sebastian (2018)

Poly(N-isopropylacrylamide) (PNIPAM) microgels respond to changes in temperature by shrinking in aqueous solution above their volume phase transition temperature (VPTT). Additionally, they shrink in mixtures of water and ethanol, although both individual liquids are good solvents. This is termed cononsolvency. Combined DLS experiments and MD simulations show that microgels in aqueous alcohol bu...

Rhodium-catalysed hydroformylation of long-chain alkenes in aqueous multiphase systems: Kinetic studies and systematic process development

Pogrzeba, Tobias (2018)

In the course of the development of new sustainable industrial chemical processes the exploitation of switchable solvent systems is increasingly investigated in various fields. The application of highly efficient catalysts and safer solvents is mandatory to make a step towards a greener chemistry, as well as to find innovative ways to reduce waste from chemical reactions. Consequently, the use ...