Inst. Chemie

1080 Items

Recent Submissions
In-situ structure and catalytic mechanism of NiFe and CoFe layered double hydroxides during oxygen evolution

Dionigi, Fabio ; Zeng, Zhenhua ; Sinev, Ilya ; Merzdorf, Thomas ; Deshpande, Siddharth ; Lopez, Miguel Bernal ; Kunze, Sebastian ; Zegkinoglou, Ioannis ; Sarodnik, Hannes ; Dingxin Fan, Dingxin Fan ; Bermann, Arno ; Drnec, Jakub ; Araujo, Jorge Ferreira de ; Gliech, Manuel ; Teschner, Detre ; Zhu, Jing ; Li, Wei-Xue ; Greeley, Jeffrey ; Cuenya, Beatriz Roldan ; Strasser, Peter (2020-05-20)

NiFe and CoFe (MFe) layered double hydroxides (LDHs) are among the most active electrocatalysts for the alkaline oxygen evolution reaction (OER). Herein, we combine electrochemical measurements, operando X-ray scattering and absorption spectroscopy, and density functional theory (DFT) calculations to elucidate the catalytically active phase, reaction center and the OER mechanism. We provide the...

Catalytic dioxygen reduction mediated by a tetranuclear cobalt complex supported on a stannoxane core

Chandra, Anirban ; Mebs, Stefan ; Kundu, Subrata ; Kuhlmann, Uwe ; Hildebrandt, Peter ; Dau, Holger ; Ray, Kallol (2020-04-08)

The synthesis, spectroscopic characterization (infrared, electron paramagnetic resonance and X-ray absorption spectroscopies) and density functional theoretical calculations of a tetranuclear cobalt complex Co4L1 involving a nonheme ligand system, L1, supported on a stannoxane core are reported. Co4L1, similar to the previously reported hexanuclear cobalt complex Co6L2, shows a unique ability t...

Anticipating alien cells with alternative genetic codes: away from the alanine world!

Kubyshkin, Vladimir ; Budisa, Nediljko (2019-07-03)

Can we make life with a different genetic amino acid repertoire? Can we expect organisms which would keep newly given genetic code associations permanently? To address these questions, we would like to analyze the existent genetic code amino acid repertoire as formed from derivatives of alanine. Derivation from alanine leads to the α-helix based biological world, the Alanine World, whereas vari...

Vibrational characterization of a diiron bridging hydride complex – a model for hydrogen catalysis

Gee, Leland B. ; Pelmenschikov, Vladimir ; Wang, Hongxin ; Mishra, Nakul ; Liu, Yu-Chiao ; Yoda, Yoshitaka ; Tamasaku, Kenji ; Chiang, Ming-Hsi ; Cramer, Stephen P. (2020-05-06)

A diiron complex containing a bridging hydride and a protonated terminal thiolate of the form [(μ,κ2-bdtH)(μ-PPh2)(μ-H)Fe2(CO)5]+ has been investigated through 57Fe nuclear resonance vibrational spectroscopy (NRVS) and interpreted using density functional theory (DFT) calculations. We report the Fe–μH–Fe wagging mode, and indications for Fe–μD stretching vibrations in the D-isotopologue, observ...

Hydroxy-bridged resting states of a [NiFe]-hydrogenase unraveled by cryogenic vibrational spectroscopy and DFT computations

Caserta, Giorgio ; Pelmenschikov, Vladimir ; Lorent, Christian ; Waffo, Armel F. Tadjoung ; Katz, Sagie ; Lauterbach, Lars ; Schoknecht, Janna ; Wang, Hongxin ; Yoda, Yoshitaka ; Tamasaku, Kenji ; Kaupp, Martin ; Hildebrandt, Peter ; Lenz, Oliver ; Cramer, Stephen P. ; Zebger, Ingo (2020-12-11)

The catalytic mechanism of [NiFe]-hydrogenases is a subject of extensive research. Apart from at least four reaction intermediates of H2/H+ cycling, there are also a number of resting states, which are formed under oxidizing conditions. Although not directly involved in the catalytic cycle, the knowledge of their molecular structures and reactivity is important, because these states usually acc...

Dihydrogen-driven NADPH recycling in imine reduction and P450-catalyzed oxidations mediated by an engineered O2-tolerant hydrogenase

Preissler, Janina ; Reeve, Holly A. ; Zhu, Tianze ; Nicholson, Jake ; Urata, Kouji ; Lauterbach, Lars ; Wong, Luet L. ; Vincent, Kylie A. ; Lenz, Oliver (2020-06-16)

The O2-tolerant NAD+-reducing hydrogenase (SH) from Ralstonia eutropha (Cupriavidus necator) has already been applied in vitro and in vivo for H2-driven NADH recycling in coupled enzymatic reactions with various NADH-dependent oxidoreductases. To expand the scope for application in NADPH-dependent biocatalysis, we introduced changes in the NAD+-binding pocket of the enzyme by rational mutagenes...

On the crucial role of isolated electronic states in the thermal reaction of ReC+ with dihydrogen

Li, Jilai ; Geng, Caiyun ; Weiske, Thomas ; Schwarz, Helmut (2020-03-17)

Presented here is that isolated, long-lived electronic states of ReC+ serve as the root cause for distinctly different reactivities of this diatomic ion in the thermal activation of dihydrogen. Detailed high-level quantum chemical calculations support the experimental findings obtained in the highly diluted gas phase using FT-ICR mass spectrometry. The origin for the existence of these long-liv...

Counter-intuitive gas-phase reactivities of [V2]+ and [V2O]+ towards CO2 reduction: Insight from electronic structure calculations

Li, Jilai ; Geng, Caiyun ; Weiske, Thomas ; Schwarz, Helmut (2020-02-26)

[V2O]+ remains “invisible” in the thermal gas-phase reaction of bare [V2]+ with CO2 giving rise to [V2O2]+; this is because the [V2O]+ intermediate is being consumed more than 230 times faster than it is generated. However, the fleeting existence of [V2O]+ and its involvement in the [V2]+ → [V2O2]+ chemistry are demonstrated by a cross-over labeling experiment with a 1:1 mixture of C16O2/C18O2,...

Silylium-ion-promoted (5+1) cycloaddition of aryl-substituted vinylcyclopropanes and hydrosilanes involving aryl migration

He, Tao ; Wang, Guoqiang ; Bonetti, Vittorio ; Klare, Hendrik F. T. ; Oestreich, Martin (2020-04-17)

A transition-metal-free (5+1) cycloaddition of aryl-substituted vinylcyclopropanes (VCPs) and hydrosilanes to afford silacyclohexanes is reported. Catalytic amounts of the trityl cation initiate the reaction by hydride abstraction from the hydrosilane, and further progress of the reaction is maintained by self-regeneration of the silylium ions. The new reaction involves a [1,2] migration of an ...

Synthesis of a counteranion-stabilized bis(silylium) ion

Wu, Qian ; Roy, Avijit ; Wang, Guoqiang ; Irran, Elisabeth ; Klare, Hendrik F. T. ; Oestreich, Martin (2020-03-26)

The preparation of a molecule with two alkyl-tethered silylium-ion sites from the corresponding bis(hydrosilanes) by two-fold hydride abstraction is reported. The length of the conformationally flexible alkyl bridge is crucial as otherwise the hydride abstraction stops at the stage of a cyclic bissilylated hydronium ion. With an ethylene tether, the open form of the hydronium-ion intermediate i...

Immobilization of an iridium pincer complex in a microporous polymer for application in room-temperature gas phase catalysis

König, Michaela ; Rigo, Massimo ; Chaoui, Nicolas ; Ngoc, Trung Tran ; Epping, Jan Dirk ; Schmidt, Johannes ; Pachfule, Pradip ; Ye, Meng-Yang ; Trunk, Matthias ; Teichert, Johannes F. ; Drieß, Matthias ; Thomas, Arne (2020-07-02)

An iridium dihydride pincer complex [IrH2(POCOP)] is immobilized in a hydroxy-functionalized microporous polymer network using the concepts of surface organometallic chemistry. The introduction of this novel, truly innocent support with remote OH-groups enables the formation of isolated active metal sites embedded in a chemically robust and highly inert environment. The catalyst maintained high...

Stable Actinide π Complexes of a Neutral 1,4-Diborabenzene

Paprocki, Valerie ; Hrobárik, Peter ; Harriman, Katie L. M. ; Luff, Martin S. ; Kupfer, Thomas ; Kaupp, Martin ; Murugesu, Muralee ; Braunschweig, Holger (2020-04-24)

The π coordination of arene and anionic heteroarene ligands is a ubiquitous bonding motif in the organometallic chemistry of d-block and f-block elements. By contrast, related π interactions of neutral heteroarenes including neutral bora-π-aromatics are less prevalent particularly for the f-block, due to less effective metal-to-ligand backbonding. In fact, π complexes with neutral heteroarene l...

Electrocatalytic CO2 reduction on CuOx nanocubes: Tracking the evolution of chemical state, geometric structure, and catalytic selectivity using operando spectroscopy

Möller, Tim ; Scholten, Fabian ; Thanh, Trung Ngo ; Sinev, Ilya ; Timoshenko, Janis ; Wang, Xingli ; Jovanov, Zarko ; Gliech, Manuel ; Cuenya, Beatriz Roldan ; Varela, Ana Sofia ; Strasser, Peter (2020-07-06)

The direct electrochemical conversion of carbon dioxide (CO2) into multi-carbon (C2+) products still faces fundamental and technological challenges. While facet-controlled and oxide-derived Cu materials have been touted as promising catalysts, their stability has remained problematic and poorly understood. Herein we uncover changes in the chemical and morphological state of supported and unsupp...

Morphology and mechanism of highly selective Cu(II) oxide nanosheet catalysts for carbon dioxide electroreduction

Wang, Xingli ; Klingan, Katharina ; Klingenhof, Malte ; Möller, Tim ; Araújo, Jorge Ferreira de ; Martens, Isaac ; Bagger, Alexander ; Jiang, Shan ; Rossmeisl, Jan ; Dau, Holger ; Strasser, Peter (2021-02-04)

Cu oxides catalyze the electrochemical carbon dioxide reduction reaction (CO2RR) to hydrocarbons and oxygenates with favorable selectivity. Among them, the shape-controlled Cu oxide cubes have been most widely studied. In contrast, we report on novel 2-dimensional (2D) Cu(II) oxide nanosheet (CuO NS) catalysts with high C2+ products, selectivities (> 400 mA cm−2) in gas diffusion electrodes (GD...

Eliciting the silent lucensomycin biosynthetic pathway in Streptomyces cyanogenus S136 via manipulation of the global regulatory gene adpA

Yushchuk, Oleksandr ; Ostash, Iryna ; Mösker, Eva ; Vlasiuk, Iryna ; Deneka, Maksym ; Rückert, Christian ; Busche, Tobias ; Fedorenko, Victor ; Kalinowski, Jörn ; Süssmuth, Roderich D. ; Ostash, Bohdan (2021-02-10)

Actinobacteria are among the most prolific sources of medically and agriculturally important compounds, derived from their biosynthetic gene clusters (BGCs) for specialized (secondary) pathways of metabolism. Genomics witnesses that the majority of actinobacterial BGCs are silent, most likely due to their low or zero transcription. Much effort is put into the search for approaches towards activ...

Editorial for the Special Issue on Nanomaterials in Health Care Diagnostics

Altintas, Zeynep (2021-04-26)

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Quantification of Local Electric Field Changes at the Active Site of Cytochrome c Oxidase by Fourier Transform Infrared Spectroelectrochemical Titrations

Baserga, Federico ; Dragelj, Jovan ; Kozuch, Jacek ; Mohrmann, Hendrik ; Knapp, Ernst-Walter ; Stripp, Sven T. ; Heberle, Joachim (2021-04-27)

Cytochrome c oxidase (CcO) is a transmembrane protein complex that reduces molecular oxygen to water while translocating protons across the mitochondrial membrane. Changes in the redox states of its cofactors trigger both O2 reduction and vectorial proton transfer, which includes a proton-loading site, yet unidentified. In this work, we exploited carbon monoxide (CO) as a vibrational Stark effe...

Isolierbare Silicium‐basierte Polykationen mit Lewis‐Superacidität

Hermannsdorfer, André ; Driess, Matthias (2020-10-15)

Molekulare Silicium‐Polykationen des Typs R2Si2+ und RSi3+ (R=H, organische Gruppe) sind Lewis‐Supersäuren und bisher in kondensierter Phase unbekannt. Wir berichten über die Synthese einer Reihe isolierbarer Terpyridinkomplexe von R2Si2+ und RSi3+, [R2Si(terpy)]2+ (R=Ph 12+; R2=C12H8 22+, (CH2)3 32+) und [RSi(terpy)]3+ (R=Ph 43+, C6H11 53+, m‐Xylyl 63+) in Form ihrer Triflat‐Salze. Die Stabili...

Design and utilization of NADH sensors in bacterial cells, specifically to monitor activity of the soluble hydrogenase of Ralstonia eutropha

Wilkening, Svea Kristina (2021)

The soluble hydrogenase (SH) of R. eutropha is a potential candidate for application in clean energy generation in a post-fossil age. In order to elucidate its mode of action, and possibly deduce general parameters for a biotechnological implementation, it is desirable to monitor the protein in vivo. The hydrogenase couples the oxidation of H2 to the reduction of NAD+ to NADH, offering the poss...

Stereospezifische Darstellung α-chiraler Tetraorganosilane mittels Kupfer(I)-katalysierter Silylierung aktivierter enantiomerenangereicherter Alkylelektrophile

Scharfbier, Jonas (2021)

Die vorliegende Dissertation widmet sich der katalytischen Erzeugung von kupfergebundenen Siliciumnukleophilen und deren Anwendung in stereospezifischen Substitutionsreaktionen mit aktivierten C(sp3) Elektrophilen. In einer parallelen Arbeit in der Arbeitsgruppe OESTREICH wurden bereits Kupfer(I)-katalysierte Substitutionsreaktionen mit dem aus SUGINOMEs Silylboronsäureester erzeugten Nukleoph...