Recent Submissions

  • Journal Article

    Mesoporous-silica-coated palladium-nanocubes as recyclable nanocatalyst in C–C-coupling reaction – a green approach 

    Rohleder, Darius; Vana, Philipp
    RSC Advances 2020; 10(44) p.26504-26507
    We report the straightforward design of a recyclable palladium-core–silica-shell nanocatalyst showing an excellent balance between sufficient stability and permeability. The overall process – design, catalysis and purification – is characterized by its sustainability and simplicity accompanied by a great recycling potential and ultra high yields in C–C-coupling reactions.
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  • Journal Article

    Exfoliated near infrared fluorescent silicate nanosheets for (bio)photonics 

    Selvaggio, Gabriele; Chizhik, Alexey; Nißler, Robert; Kuhlemann, llyas; Meyer, Daniel; Vuong, Loan; Preiß, Helen; Herrmann, Niklas; Mann, Florian A.; Lv, Zhiyi; et al.
    Oswald, Tabea A.Spreinat, AlexanderErpenbeck, LuiseGroßhans, JörgKarius, VolkerJanshoff, AndreasPablo Giraldo, JuanKruss, Sebastian
    Nature Communications 2020; 11(1) p.1-11: Art. 1495
    Imaging of complex (biological) samples in the near-infrared (NIR) is beneficial due toreduced light scattering, absorption, phototoxicity, and autofluorescence. However, there arefew NIRfluorescent materials known and suitable for biomedical applications. Here weexfoliate the layered pigment $CaCuSi_4O_{10}$ (Egyptian Blue, EB) via ball milling and facile tipsonication into NIRfluorescent nanosheets (EB-NS). The size of EB-NS can be tailored todiameters <20 nm and heights down to 1 nm. EB-NSfluoresce at 910 nm and thefluorescenceintensity correlates with the number of $Cu^{2+}$ ions. Furthermore, EB-NS display no bleachingand high brightness compared with other NIRfluorophores. The versatility of EB-NS isdemonstrated by in-vivo single-particle tracking and microrheology measurements inDro-sophila melanogasterembryos. EB-NS can be uptaken by plants and remotely detected in alow-cost stand-off detection setup. In summary, EB-NS have the potential for a wide range ofbioimaging applications.
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  • Journal Article

    Electrochemical Access to Aza-Polycyclic Aromatic Hydrocarbons: Rhoda-Electrocatalyzed Domino Alkyne Annulations 

    Kong, Wei-Jun; Shen, Zhigao; Finger, Lars H.; Ackermann, Lutz
    Angewandte Chemie International Edition(59) p.1-7
    Nitrogen-doped polycyclic aromatic hydrocarbons (aza-PAHs) have found broad applications in material sciences. Herein, a modular electrochemical synthesis of aza-PAHs was developed via a rhodium-catalyzed cascade C-H activation and alkyne annulation. A multifunctional O-methylamidoxime enabled the high chemo- and regioselectivity. The isolation of two key rhodacyclic intermediates made it possible to delineate the exact order of three C-H activation steps. In addition, the metalla-electrocatalyzed multiple C-H transformation is characterized by unique functional group tolerance, including highly reactive iodo and azido groups.
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  • Journal Article

    An Unprecedented Fully H - Substituted Phosphate Hydride Sr5(PO4)3H Expanding the Apatite Family 

    Mutschke, Alexander; Wylezich, Thomas; Ritter, Clemens; Karttunen, Antti J.; Kunkel, Nathalie
    European Journal of Inorganic Chemistry 2019; 2019(48) p.5073-5076
    The apatite family is a mineral class that also contains the biologically very important hydroxyapatite. Here, we are reporting on the synthesis and characterization of a fully hydride‐substituted strontium apatite, which could be obtained via mechanochemical synthesis and subsequent annealing treatment. The full substitution by hydride anions is proven by various methods, such as neutron powder diffraction of a deuterated sample Sr5(PO4)3D, as well 1H MAS solid state NMR combined with quantum chemical calculations, vibrational spectroscopy and elemental analysis. The present work expands the apatite family from the known halide and hydroxide apatites to the fully hydride‐anion‐substituted variant and is expected to open up a new field of materials containing coexistent phosphate and hydride anions.
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  • Journal Article

    Sequential Double Dearomatization of the Pyrazolate-Based “Two-in-One” Pincer Ligand in a Dinuclear Rhodium(I) Complex 

    Gers-Barlag, Alexander; Goursot, Pierre; Li, Ming; Dechert, Sebastian; Meyer, Franc
    European Journal of Inorganic Chemistry 2019; 2019(28) p.3329-3334
    A binucleating pyrazolate‐based ligand providing two tridentate PNN compartments is shown to form a dinuclear rhodium(I) complex [L{Rh(CO)}2](PF6) (1) that can be deprotonated at both side arm methylene groups between pyridine and phosphino donors to give K[L**{Rh(CO)}2] (3). Sequential twofold deprotonation has been monitored by NMR and UV/Vis spectroscopy and proceeds via the neutral intermediate L*{Rh(CO)}2 (2). X‐ray crystallographic characterization of 1 and the K[2,2,2]+ salt 3′ ([2,2,2] is a cryptand) evidences pyridine dearomatization upon deprotonation, and all spectroscopic and structural signatures are in good agreement with those of related mononuclear rhodium complexes based on a common PNN pincer ligand, which corroborates that pyrazolate‐bridged L– is best described as a scaffold with two pincer‐type subunits.
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  • Journal Article

    Oxidative Coupling of Terminal Rhenium Pnictide Complexes 

    Abbenseth, Josh; Diefenbach, Martin; Hinz, Alexander; Alig, Lukas; Würtele, Christian; Goicoechea, Jose M.; Holthausen, Max C.; Schneider, Sven
    Angewandte Chemie International Edition 2019; 58(32) p.10966-10970
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  • Journal Article

    A Terminal Iridium Oxo Complex with a Triplet Ground State 

    Delony, Daniel; Kinauer, Markus; Diefenbach, Martin; Demeshko, Serhiy; Würtele, Christian; Holthausen, Max C.; Schneider, Sven
    Angewandte Chemie International Edition 2019; 58(32) p.10971-10974
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  • Journal Article

    First-Row Transition Metal (De)Hydrogenation Catalysis Based On Functional Pincer Ligands 

    Alig, Lukas; Fritz, Maximilian; Schneider, Sven
    Chemical Reviews 2018; 119(4) p.2681-2751
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  • Journal Article

    Metal-Ligand Cooperative Synthesis of Benzonitrile by Electrochemical Reduction and Photolytic Splitting of Dinitrogen 

    Schendzielorz, Florian; Finger, Markus; Abbenseth, Josh; Würtele, Christian; Krewald, Vera; Schneider, Sven
    Angewandte Chemie International Edition 2018; 58(3) p.830-834
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  • Journal Article

    Iron‐Electrocatalyzed C−H Arylations: Mechanistic Insights into Oxidation‐Induced Reductive Elimination for Ferraelectrocatalysis 

    Zhu, Cuiju; Stangier, Maximilian; Oliveira, João C. A.; Massignan, Leonardo; Ackermann, Lutz
    Chemistry – A European Journal 2019; 25(71) p.16382-16389
    Despite major advances, organometallic C-H transformations are dominated by precious 5d and 4d transition metals, such as iridium, palladium and rhodium. In contrast, the unique potential of less toxic Earth-abundant 3d metals has been underexplored. While iron is the most naturally abundant transition metal, its use in oxidative, organometallic C-H activation has faced major limitations due to the need for superstoichiometric amounts of corrosive, cost-intensive DCIB as the sacrificial oxidant. To fully address these restrictions, we describe herein the unprecedented merger of electrosynthesis with iron-catalyzed C-H activation through oxidation-induced reductive elimination. Thus, ferra- and manganaelectro-catalyzed C-H arylations were accomplished at mild reaction temperatures with ample scope by the action of sustainable iron catalysts, employing electricity as a benign oxidant.
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  • Journal Article

    Hydrosilane Synthesis by Catalytic Hydrogenolysis of Chlorosilanes and Silyl Triflates 

    Glüer, Arne; Schweizer, Julia I.; Karaca, Uhut S.; Würtele, Christian; Diefenbach, Martin; Holthausen, Max C.; Schneider, Sven
    Inorganic Chemistry 2018; 57(21) p.13822-13828
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  • Journal Article

    Iron catalyzed hydrogenation and electrochemical reduction of CO 2 : The role of functional ligands 

    Glüer, Arne; Schneider, Sven
    Journal of Organometallic Chemistry 2018; 861 p.159-173
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  • Journal Article

    Synthesis of Benzonitrile from Dinitrogen 

    Klopsch, Isabel; Schendzielorz, Florian; Volkmann, Christian; Würtele, Christian; Schneider, Sven
    Zeitschrift für anorganische und allgemeine Chemie 2018; 644(17) p.916-919
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  • Journal Article

    π‐Extended Polyaromatic Hydrocarbons by Sustainable Alkyne Annulations through Double C−H/N−H Activation 

    Gońka, Elżbieta; Yang, Long; Steinbock, Ralf; Pesciaioli, Fabio; Kuniyil, Rositha; Ackermann, Lutz
    Chemistry – A European Journal 2019; 25(71) p.16246-16250
    The widespread applications of substituted diketopyrrolopyrroles (DPPs) call for the development of efficient methods for their modular assembly. Herein, we present a π-expansion strategy for polyaromatic hydrocarbons (PAHs) by C-H activation in a sustainable fashion. Thus, twofold C-H/N-H activations were accomplished by versatile ruthenium(II)carboxylate catalysis, providing step-economical access to diversely decorated fluorogenic DPPs that was merged with late-stage palladium-catalyzed C-H arylation on the thus-assembled DPP motif.
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  • Journal Article

    Nonlinear Loading-Rate-Dependent Force Response of Individual Vimentin Intermediate Filaments to Applied Strain 

    Block, Johanna; Witt, Hannes; Candelli, Andrea; Peterman, Erwin J. G.; Wuite, Gijs J. L.; Janshoff, Andreas; Köster, Sarah
    Physical Review Letters 2017; 118(4): Art. 048101
    The mechanical properties of eukaryotic cells are to a great extent determined by the cytoskeleton, a composite network of different filamentous proteins. Among these, intermediate filaments (IFs) are exceptional in their molecular architecture and mechanical properties. Here we directly record stress-strain curves of individual vimentin IFs using optical traps and atomic force microscopy. We find a strong loading rate dependence of the mechanical response, supporting the hypothesis that IFs could serve to protect eukaryotic cells from fast, large deformations. Our experimental results show different unfolding regimes, which we can quantitatively reproduce by an elastically coupled system of multiple two-state elements.
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  • Journal Article

    Eumelanin and pheomelanin pigmentation in mollusc shells may be less common than expected: insights from mass spectrometry 

    Affenzeller, Susanne; Wolkenstein, Klaus; Frauendorf, Holm; Jackson, Daniel J.
    Frontiers in Zoology. 2019 Dec 23;16(1):47
    Background The geometric patterns that adorn the shells of many phylogenetically disparate molluscan species are comprised of pigments that span the visible spectrum. Although early chemical studies implicated melanin as a commonly employed pigment, surprisingly little evidence generated with more recent and sensitive techniques exists to support these observations. Results Here we present the first mass spectrometric investigations for the presence of eumelanin and pheomelanin in 13 different molluscan species from three conchiferan classes: Bivalvia, Cephalopoda and Gastropoda. In the bivalve Mytilus edulis we demonstrate that eumelanin mainly occurs in the outermost, non-mineralised and highly pigmented layer of the shell (often referred to as the periostracum). We also identified eumelanin in the shells of the cephalopod Nautilus pompilius and the marine gastropods Clanculus pharaonius and Steromphala adriatica. In the terrestrial gastropod Cepaea nemoralis we verify the presence of pheomelanin in a mollusc shell for the first time. Surprisingly, in a large number of brown/black coloured shells we did not find any evidence for either type of melanin. Conclusions We recommend methods such as high-performance liquid chromatography with mass spectrometric detection for the analysis of complex biological samples to avoid potential false-positive identification of melanin. Our results imply that many molluscan species employ as yet unidentified pigments to pattern their shells. This has implications for our understanding of how molluscs evolved the ability to pigment and pattern their shells, and for the identification of the molecular mechanisms that regulate these processes.
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  • Journal Article

    Ruthenium(II)‐Catalyzed Hydrogen Isotope Exchange of Pharmaceutical Drugs by C−H Deuteration and C−H Tritiation 

    Müller, Valentin; Weck, Remo; Derdau, Volker; Ackermann, Lutz
    ChemCatChem(11) p.1-6
    Well-defined ruthenium(II) biscarboxylate complexes enabled selective ortho-deuteration with weakly-coordinating, synthetically useful carboxylic acid with outstanding levels of isotopic labeling. The robust nature of the catalytic system was reflected by a broad functional group tolerance in an operationallysimple manner, allowing the isotope labeling of challenging pharmaceuticals and bioactive heterocyclic motifs. The synthetic power of our method was highlighted by the selective tritium-labeling of repaglinide, an antidiabetic drug, providing access to defined tritium labeled therapeutics.
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  • Journal Article

    Non-merohedral twinning: from minerals to proteins 

    Sevvana, Madhumati; Ruf, Michael; Usón, Isabel; Sheldrick, George M.; Herbst-Irmer, Regine
    Acta Crystallographica Section D Structural Biology 2019; 75(12) p.1040-1050
    In contrast to twinning by merohedry, the reciprocal lattices of the different domains of non-merohedral twins do not overlap exactly. This leads to three kinds of reflections: reflections with no overlap, reflections with an exact overlap and reflections with a partial overlap of a reflection from a second domain. This complicates the unit-cell determination, indexing, data integration and scaling of X-ray diffraction data. However, with hindsight it is possible to detwin the data because there are reflections that are not affected by the twinning. In this article, the successful solution and refinement of one mineral, one organometallic and two protein non-merohedral twins using a common strategy are described. The unit-cell constants and the orientation matrices were determined by the program CELL_NOW. The data were then integrated with SAINT. TWINABS was used for scaling, empirical absorption corrections and the generation of two different data files, one with detwinned data for structure solution and refinement and a second one for (usually more accurate) structure refinement against total integrated intensities. The structures were solved by experimental phasing using SHELXT for the first two structures and SHELXC/D/E for the two protein structures; all models were refined with SHELXL.
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  • Journal Article

    Visible‐Light‐Mediated Dearomatisation of Indoles and Pyrroles to Pharmaceuticals and Pesticides 

    Schilling, Waldemar; Zhang, Yu; Riemer, Daniel; Das, Shoubhik
    Chemistry – A European Journal(25) p.1-7
    Dearomatisation of indole derivatives to the corresponding isatin derivatives has been achieved with the aid of visible light and oxygen. It should be noted that isatin derivatives are highly important for the synthesis of pharmaceuticals and bioactive compounds. Notably, this chemistry works excellently with N-protected and protection-free indoles. Additionally, this methodology can also be applied to dearomatise pyrrole derivatives to generate cyclic imides in a single step. Later this methodology was applied for the synthesis of four pharmaceuticals and a pesticide called dianthalexin B. Detailed mechanistic studies revealed the actual role of oxygen and photocatalyst.
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  • Journal Article

    Synthesis of benzannelated sultams by intramolecular Pd-catalyzed arylation of tertiary sulfonamides 

    Rassadin, Valentin A; Scholz, Mirko; Klochkova, Anastasiia A; de Meijere, Armin; Sokolov, Victor V
    Beilstein Journal of Organic Chemistry 2017; 13 p.1932-1939
    A new and efficient approach to five- and six-membered benzannelated sultams by intramolecular C-arylation of tertiary 1-(methoxycarbonyl)methanesulfonamides under palladium catalysis is described. In case of the α-toluenesulfonamide derivative, an unexpected formation of a 2,3-diarylindole was observed under the same conditions.
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