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Faculty of Chemistry

Welcome to the Faculty of Chemistry

In order take the sustainability and environmental compatibility into account the research foci in chemistry have changed during the last years. The enormous importance of chemistry in economy, i.e. energy supply, development of new materials, pharmaceutical research and biotechnology, is unambiguous. The close collaboration of the Faculty of Chemistry with natural scientists and engineers of the University Stuttgart, as well as with scientists of the local Max-Planck-, Fraunhofer-, and Textile Chemistry and Chemical Fibers Institute, provides a considerable location advantage.

 

Abstracts of new Publications

Publication in Green Chemistry: An alternative method for the production of second-generation biofuels

Direct coal liquefaction (DCL) is an industrial technology for the production of liquid fuels by high-pressure and high-temperature hydroconversion of coal. The technique can also be applied to biocoals produced by hydrothermal carbonization (HTC) of biomass waste. The biofuels produced are promising with regard to the H/C molar ratio, higher heating value and oxygen content.
von Martin Trautmann, Armin Löwe and Yvonne Traa
Green Chemistry 16, 2014, 3710
DOI: 10.1039/C4GC00649F
For further information please contact
PD Dr. Yvonne Traa
Institut für Technische Chemie
Universität Stuttgart
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Publication in Angewandte Chemie: A Sink for Signals: Triplex RNA motif binds cellular cGMP after expression in mammalian cells

The transmission of signals within cells is dependent on cyclic guanosine monophosphate (cGMP) as an important second messenger. Researchers led by Clemens Richert (Institut für Organische Chemie, University of Stuttgart) and Robert Feil (Interfakultäres Institut für Biochemie, University of Tübingen) developed a RNA motif that acts as a genetically encoded sink for cGMP molecules. As the motif can be repeated multiple times in a long continuous sequence, it was named “endless”.cGMP is generated in many organ systems of mammals. It plays an important role in blood vessel relaxation and the regulation of blood pressure, and aberrant cGMP signaling might be related to cardiovascular disorders. Experimental manipulation of endogenous cGMP levels should lead to a better understanding of cGMP’s multiple functions in health and disease. While it is relatively simple to elevate intracellular cGMP levels in experiments, for example, by using nitric oxide (NO), it was not yet possible to lower intracellular cGMP concentrations artificially. The newly developed cGMP-binding RNA motif “endless” is based on a triple helix. One of the three RNA segments forms a loop enclosing a binding cavity for cGMP (see Figure).
© Wiley-VCH
The functionality of “endless” was tested in smooth muscle cells obtained from blood vessels. Live cell imaging with a cGMP biosensor was used to estimate levels of free cGMP in the cytosol. In cells that expressed an artificial “endless” gene, NO-induced cGMP signals were significantly suppressed in comparison to control cells. Thus, “endless” RNA acts as a sink for cGMP and should be very useful for future research on the physiological role of cGMP.
C. Kröner, M. Thunemann, S. Vollmer, M. Kinzer, R. Feil and C. Richert
Angewandte Chemie International Edition, 2014
DOI: 10.1002/anie.2014035792014
For further information please contact
Prof. Clemens Richert
Institut für Organische Chemie
Universität Stuttgart
E-Mail

Publication in Chemical Science: Spectroscopic Determination of Crystal Field Splittings in Lanthanide Double Deckers

We have investigated the crystal field splitting in the archetypal lanthanide-based single-ion magnets and related complexes (NBu4)+[LnPc2]– (Ln = Dy, Ho, Er; dmf = N,N-dimethylformamide) by means of far infrared and inelastic neutron scattering spectroscopies. In each case, we have found several features corresponding to direct crystal field transitions within the ground multiplet. The observation of three independent peaks in the holmium derivative enabled us to derive crystal field splitting parameters. In addition, we have carried out CASSCF calculations. We show that exploiting the interplay of CASSCF calculation (for the composition of the states) and advanced spectroscopic measurements (for accurate determination of the energies) is a very powerful approach to gain insight into the electronic structure of lanthanide-based single-molecule magnets.
by R. Marx, F. Moro, M. Dörfel, L. Ungur, M. Waters, S.D. Jiang, M. Orlita, J. Taylor, W. Frey, L.F. Chibotaru, J. van Slageren
Chem. Sci. 2014
DOI: 10.1039/C4SC00751D (2014)
For further information please contact
Prof. Joris van Slageren
Instituto of Physical Chemistry
University of Stuttgart
E-Mail

Publication in JACS: Isolation of Neutral Mononuclear Copper Complexes Stabilized by Two Cyclic (Alkyl)(amino)carbenes

Two (cAAC)2Cu complexes, featuring a two-coordinate copper atom in the formal oxidation state zero, were prepared by reducing (Et2-cAAC)2Cu+I with metallic sodium in THF, and by a one-pot synthesis using Me2-cAAC, Cu(II)Cl2, and KC8 in toluene in a molar ratio of 2:1:2, respectively. Both complexes are highly air and moisture sensitive but can be stored in the solid state for a month at room temperature. DFT calculations showed that in these complexes the copper center has a d10 electronic configuration and the unpaired electron is delocalized over two carbene carbon atoms. This was further confirmed by the EPR spectra, which exhibit multiple hyperfine lines due to the coupling of the unpaired electron with 63,65Cu isotopes, 14N, and 1H nuclei.
by D. S. Weinberger, Nurul Amin SK, K. C. Mondal, M. Melaimi, G. Bertrand, A. C. Stückl, H. W. Roesky, B. Dittrich, S. Demeshko, B. Schwederski, W. Kaim, P. Jerabek and G. Frenking
J. Am. Chem. Soc. 2014, 136, 6235-6238
DOI: dx.doi.org/10.1021/ja502521b
For further information contact
Prof. Wolfgang Kaim
Institute of Inorganic Chemistry
University of Stuttgart
E-Mail

Distinguished Paper Award of the American Cleaning Institute for a Publication in the Journal of Surfactants and Detergents

Even though foams have been the subject of intensive investigations over the last decades, many important questions related to their properties remain open. This concerns in particular foams which are stabilized by mixtures of surfactants. The present study deals with the fundamental question: which are the important parameters one needs to consider if one wants to characterize foams properly? We give an answer to this question by providing a measuring protocol which we apply to well-known surfactant systems. The surfactants of choice are the two non-ionic surfactants n-dodecyl-β-d-maltoside (β-C12G2) and hexaethyleneglycol monododecyl ether (C12E6) as well as their 1:1 mixture. Following the suggested protocol, we generated data which allow discussion of the influence of the surfactant structure and of the composition on the time evolution of the foam volume, the liquid fraction, the bubble size and the bubble size distribution. This paper shows that different foam properties can be assigned to different surfactant structures, which is the crucial point if one wants to tailor-make surfactants for specific applications.
by Julia Boos, Wiebke Drenckhan, Cosima Stubenrauch
Journal of Surfactants and Detergents, Volume 16, (October 2013) p. 1-12
For further information please contact
Prof. Cosima Stubenrauch
Institute of Physical Chemistry
University of Stuttgart
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Publication in Angewandte Chemie: A Rechargeable Hydrogen Battery Based on Ru Catalysis

Apart from energy generation, the storage and liberation of energy are among the major problems in establishing a sustainable energy supply chain. Herein we report the development of a rechargeable H2 battery which is based on the principle of the Ru-catalyzed hydrogenation of CO2 to formic acid (charging process) and the Ru-catalyzed decomposition of formic acid to CO2 and H2 (discharging process). Both processes are driven by the same catalyst at elevated temperature either under pressure (charging process) or pressure-free conditions (discharging process). Up to five charging–discharging cycles were performed without decrease of storage capacity. The resulting CO2/H2 mixture is free of CO and can be employed directly in fuel-cell technology.
by M. Sc. Shih-Fan Hsu, Dipl.-Chem. Susanne Rommel, M. Sc. Philipp Eversfield, Dr. Keven Muller, Prof. Dr. Elias Klemm, Prof. Dr. Werner R. Thiel und Prof. Dr. Bernd Plietker,*
Angew. Chemie, 2014
DOI: 10.1002/anie.201310972
Fur further information please contact
Prof. Bernd Plietker
Institute of Organic Chemistry
University of Stuttgart
E-Mail

Publication in Advanced Energy Materials: Charge Transport Anisotropy in Highly Oriented Thin Films of the Acceptor Polymer P(NDI2OD-T2)

This publication by Sabine Ludwigs and her PhD students Kim Tremel and Florian Fischer in collaboration with scientists from Strasbourg, Dresden and Potsdam investigates the morphology of the n-type semicrystalline polymer P(NDI2OD-T2) and establishes relationships to absorption characteristics and charge transport in thin films. Charge transport anisotropy of highly oriented films (obtained by high temperature rubbing & post-annealing) reveals average mobilities as high as 0.1 cm²/Vs along the polymer chains, i.e. parallel to the rubbing direction, whereas mobilities normal to the rubbing direction are approximately one order of magnitude lower. Interestingly this high anisotropy along the polymer chain is consistent with our recent findings for poly(3-hexylthiophene) (see Crossland, Ludwigs et al. Adv. Mater. 2012, 24, 839).
by K. Tremel , F.S.U. Fischer , N. Kayunkid , R. Di Pietro, R. Tkachov , A. Kiriy, D. Neher, S. Ludwigs , M. Brinkmann
Adv. Energy Mater. 2014
DOI: 10.1002/aenm.201301659
For further information please contact:
Prof. Sabine Ludwigs
Institute of Polymer Chemistry
University of Stuttgart
E-Mail

Publication in Advanced Materials: Organic Solar Cells: On the Efficiency of Charge Transfer State Splitting in Polymer: Fullerene Solar Cells

New insights in the efficiency of charge transfer state splitting in poly(3-hexylthiophene): fullerene solar cells were recently shown in a collaborative project between Potsdam, Stanford, Raleigh, Berkeley, Dresden and Stuttgart. Sabine Ludwigs and her PhD student Florian Fischer contributed to this highly interdisciplinary research project by determining energy levels both of the pure components and of the polymer blend films with their in-situ spectroelectrochemistry measurements.
by S. Albrecht, K. Vandewal, J.R. Tumbleston, F.S.U. Fischer, J.D. Douglas, J.M.J. Fréchet, S. Ludwigs, H. Ade, A. Salleo, and D. Neher
Adv. Mater. 2014, 26, 2533
DOI: 10.1002/adma.201470107
For further information please contact:
Prof. Sabine Ludwigs
Institute of Polymer Chemistry
University of Stuttgart

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Publication in Angewandte Chemie: C4 Cumulene and the Corresponding Air-Stable Radical Cation and Dication

A neutral C4 cumulene 1 that includes a cyclic alkyl(amino) carbene (cAAC), its air-stable radical cation 1.+, and dication 12+ have been synthesized. The redox property of 1.+ was studied by cyclic voltammetry. EPR and theoretical calculations show that the unpaired electron in 1.+ is mainly delocalized over the central C4 backbone. The commercially available CBr4 is utilized as a source of dicarbon in the cumulene synthesis.
by Yan Li, Kartik Chandra Mondal, Prinson P. Samuel, Hongping Zhu, Claudia M. Orben, Saravanan Panneerselvam, Birger Dittrich, Brigitte Schwederski, Wolfgang Kaim, Totan Mondal, Debasis Koley, Herbert W. Roesky
Angew. Chem. 2014, 126, 4252-4256
DOI: 10.1002/ange.201310975
For further information please contact:
Prof. Wolfgang Kaim
Institute of Inorganic Chemistry
University of Stuttgart
E-Mail

Publication in Angewandte Chemie: Anomalous Diamagnetic Susceptibility in 13-Atom Platinum Nanocluster Superatoms

We are used to being able to predict diamagnetic susceptibilities χD to a good approximation in atomic increments since there is normally little dependence on the chemical environment. Surprisingly, we find from SQUID magnetization measurements that the χD per Pt atom of zeolite-supported Pt13 nanoclusters exceeds that of Pt2+ ions by a factor of 37–50. The observation verifies an earlier theoretical prediction. The phenomenon can be understood nearly quantitatively on the basis of a simple expression for diamagnetic susceptibility and the superatom nature of the 13-atom near-spherical cluster. The two main contributions come from ring currents in the delocalized hydride shell and from cluster molecular orbitals hosting the Pt 5d and Pt 6s electrons.
by Roduner, E., Jensen, C., van Slageren, J., Rakoczy, R. A., Larlus, O. and Hunger, M.
Angew. Chemie, 2014
doi: 10.1002/ange.201310637
For further information please contact:
Prof. Joris van Slageren
Institute of Physical Chemistry
University of Stuttgart
E-Mail

Publication in JACS: The Total Syntheses of Guttiferone A and 6-epi-Guttiferone A

Polyprenylated polycyclic acylphloroglucinols (PPAP) are a constantly growing class of natural products that exhibit a common bicyclo[3.3.1]nonatrione core and consist of currently more than 200 members. A subclassification among the various natural products of this class includes the position of the exocyclic acyl group, the prenylation grade of the core, and the relative configuration at C-7 within the core. About 10% of the reported structures, however, possess an additional chiral center at C-6. Herein we describe a straightforward access to guttiferone A and epi-guttiferone A, in which full control of stereoselectivity is achieved via conformational control, and a strict separation of framework decorating from framework constructing operations sets the stage for a short 13-step synthesis.
by Fiene Horeischi , Nicole Biber , and Bernd Plietker
J. Am. Chem. Soc. 2014, 136 (10), 4026
DOI: 10.1021/ja500063a
For further information please contact:
Prof. Bernd Plietker
Institute of Organic Chemistry
University of Stuttgart
E-Mail

Publication in JACS: Stabilization of a Cobalt–Cobalt Bond by Two Cyclic Alkyl Amino Carbenes


by Kartik Chandra Mondal, Prinson P. Samuel, Herbert W. Roesky, Elena Carl, Regine Herbst-Irmer, Dietmar Stalke, Brigitte Schwederski, Wolfgang Kaim, Liviu Ungur, Liviu Chibotaru, Markus Herrmann and Gernot Frenking
J. Am. Chem. Soc. 2014, 136, 1770−1773
DOI: 10.1021/ja4123285
For further information please contact:
Prof. Wolfgang Kaim
Institute of Inorganic Chemistry
University of Stuttgart
E-Mail

Publication in Angewandte Chemie: The Electronic Ground State of [Fe(CO)3(NO)]: A Spectroscopic and Theoretical Study

During the past 10 years iron-catalyzed reactions have become established in the field of organic synthesis. For example, the complex anion [Fe(CO)3(NO)], which was originally described by Hogsed and Hieber, shows catalytic activity in various organic reactions. This anion is commonly regarded as being isoelectronic with [Fe(CO)4]2−, which, however, shows poor catalytic activity. The spectroscopic and quantum chemical investigations presented herein reveal that the complex ferrate [Fe(CO)3(NO)]cannot be regarded as a Fe−II species, but rather is predominantly a Fe0 species, in which the metal is covalently bonded to NO by two π-bonds. A metal–N σ-bond is not observed.
by M. Sc. Johannes E. M. N. Klein, Dr. Burkhard Miehlich, Dr. Michael S. Holzwarth, Prof. Dr. Matthias Bauer, Dipl.-Chem. Magdalena Milek, Dr. Marat M. Khusniyarov, Dr. Gerald Knizia, Prof. Dr. Hans-Joachim Werner, Prof. Dr. Bernd Plietker,*
Angew. Chem. Int. Ed. 2014, 53
DOI: 0.1002/anie.201309767
For further information please contact:
Prof. Bernd Plietker
Institute of Organic Chemistry
University of Stuttgart
E-Mail