TY - JOUR A1 - Ghaisari, Sara A1 - Winklhofer, Michael A1 - Strauch, Peter A1 - Klumpp, Stefan A1 - Faivre, Damien T1 - Magnetosome Organization in Magnetotactic Bacteria Unraveled by Ferromagnetic Resonance Spectroscopy JF - Biophysical journal N2 - Magnetotactic bacteria form assemblies of magnetic nanoparticles called magnetosomes. These magnetosomes are typically arranged in chains, but other forms of assemblies such as clusters can be observed in some species and genetic mutants. As such, the bacteria have developed as a model for the understanding of how organization of particles can influence the magnetic properties. Here, we use ferromagnetic resonance spectroscopy to measure the magnetic anisotropies in different strains of Magnetosprillum gtyphiswaldense MSR-1, a bacterial species that is amendable to genetic mutations. We combine our experimental results with a model describing the spectra. The model includes chain imperfections and misalignments following a Fisher distribution function, in addition to the intrinsic magnetic properties of the magnetosomes. Therefore, by applying the model to analyze the ferromagnetic resonance data, the distribution of orientations in the bulk sample can be retrieved in addition to the average magnetosome arrangement. In this way, we quantitatively characterize the magnetosome arrangement in both wild-type cells and Delta mamJ mutants, which exhibit differing magnetosome organization. Y1 - 2017 U6 - https://doi.org/10.1016/j.bpj.2017.06.031 SN - 0006-3495 SN - 1542-0086 VL - 113 SP - 637 EP - 644 PB - Cell Press CY - Cambridge ER - TY - JOUR A1 - Zabel, André A1 - Winter, Alette A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Strauch, Peter T1 - Tetrabromidocuprates(II)-Synthesis, Structure and EPR JF - International journal of molecular sciences N2 - Metal-containing ionic liquids (ILs) are of interest for a variety of technical applications, e.g., particle synthesis and materials with magnetic or thermochromic properties. In this paper we report the synthesis of, and two structures for, some new tetrabromidocuprates(II) with several “onium” cations in comparison to the results of electron paramagnetic resonance (EPR) spectroscopic analyses. The sterically demanding cations were used to separate the paramagnetic Cu(II) ions for EPR measurements. The EPR hyperfine structure in the spectra of these new compounds is not resolved, due to the line broadening resulting from magnetic exchange between the still-incomplete separated paramagnetic Cu(II) centres. For the majority of compounds, the principal g values (g|| and gK) of the tensors could be determined and information on the structural changes in the [CuBr4]2- anions can be obtained. The complexes have high potential, e.g., as ionic liquids, as precursors for the synthesis of copper bromide particles, as catalytically active or paramagnetic ionic liquids. KW - tetrabromidocuprate(II) KW - X-ray structure KW - electron paramagnetic resonance KW - copper(II) Y1 - 2016 U6 - https://doi.org/10.3390/ijms17040596 VL - 17 IS - 4 PB - MDPI CY - Basel ER - TY - GEN A1 - Zabel, André A1 - Winter, Alette A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Strauch, Peter T1 - Tetrabromidocuprates(II)-Synthesis, Structure and EPR N2 - Metal-containing ionic liquids (ILs) are of interest for a variety of technical applications, e.g., particle synthesis and materials with magnetic or thermochromic properties. In this paper we report the synthesis of, and two structures for, some new tetrabromidocuprates(II) with several “onium” cations in comparison to the results of electron paramagnetic resonance (EPR) spectroscopic analyses. The sterically demanding cations were used to separate the paramagnetic Cu(II) ions for EPR measurements. The EPR hyperfine structure in the spectra of these new compounds is not resolved, due to the line broadening resulting from magnetic exchange between the still-incomplete separated paramagnetic Cu(II) centres. For the majority of compounds, the principal g values (g|| and gK) of the tensors could be determined and information on the structural changes in the [CuBr4]2- anions can be obtained. The complexes have high potential, e.g., as ionic liquids, as precursors for the synthesis of copper bromide particles, as catalytically active or paramagnetic ionic liquids. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 226 KW - tetrabromidocuprate(II) KW - X-ray structure KW - electron paramagnetic resonance KW - copper(II) Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-91470 ER - TY - JOUR A1 - Siebold, M. A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Strauch, Peter T1 - Heterobimetallic 3d-4-complexes with bis(1;2-dithiooxalato)nickelate(II) as planar bridging block N2 - Planar bis(1,2-dithiooxalato)nickelates(II) react in aqueous solutions of lanthanide ions to form pentanuclear, heterobimetallic complexes of the general composition [{Ln(H2O)(n)}(2)- {Ni(dto)(2)}(3)] (.) xH(2)O (Ln = Y3+, La3+, Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+, Lu3+; n = 4 or 5; x = 9-12). With [{Nd(H2O)(5)}(2){Ni(S2C2O2)(2)}(3)] (.) xH(2)O (x = 10-12) (1) and [{Er(H2O)(4)}(2){Ni(S2C2O2)(2)}(3)] (.) xH(2)O (x = 9- 10) (2) we were able to isolate two complexes of this series as single crystals, which were characterized by X-ray structure analysis. Depending on the individual ionic radii of the lanthanide ions, the compounds crystallize in two different crystal systems with the following unit cell parameters: 1, monoclinic in P2(1)/c with a = 11.3987(13), b = 11.4878(8), c = 20.823(2)angstrom , beta = 98.907(9)degrees and Z = 2; 2, triclinic in P (1) over bar with a = 10.5091(6), b = 11.0604(6), c = 11.2823(6) angstrom, alpha = 107.899(4)degrees, beta = 91.436(4)degrees, gamma = 112.918(4)degrees and Z = 1. The channels and cavities appearing in the packing of the molecules are occupied by uncoordinated water molecules. High magnetic moments up to 14.65 BM./f.u. have been observed at room temperature due to the combined moments of the individual lanthanide ions Y1 - 2005 SN - 0932-0776 ER - TY - JOUR A1 - Kozlevcar, Bojan A1 - Humar, M. B. A1 - Strauch, Peter A1 - Leban, I T1 - Fixation of copper(II) ions in aqueous solution to lignin model compound vanillin in an absence of the nitrogen donor ligands : structural and EPR correlation N2 - In order to elucidate the interactions of copper with wood, three mononuclear copper(II) coordination compounds with a vanillinate anion, cis-[Cu(C8H7O3)(2)(H2O)(2)] (1), trans-[Cu(C8H7O3)(2)(H2O)(2)].2H(2)O (2), and trans- [Cu(C8H7O3)(2)(H2O)(2)] (3), have been characterized. X-ray structure analysis of the cis isomer 1 reveals two bidentate vanillinate ions coordinated via methoxy (Cu-O1 2.260(2) angstrom) and deprotonated hydroxy oxygen atoms (Cu-O2 1.909(2) angstrom), and two water molecules (Cu-O1w 2.087(2) angstrom) in the octahedral CuO6 chromophore. Two axes O1-Cu- O1w' in the octahedron have the same length, while the third axis O2-Cu-O2' is shorter. This is in agreement with the room temperature EPR spectrum of 1, showing two signals (g(12) 2.302, g(3) 2.005), but interestingly, three signals (g(1) 2.393, g(2) 2.214, g(3) 2.010) in the 115 K spectrum were found. The same coordination atoms were found also in the trans isomer 2 (Cu-O2 1.950(2), Cu-O1w 1.994(2), Cu-O1 2.334(2) angstrom), however here, two axes of almost equal length are short (O2-Cu-O2' O1w-Cu-O1w'), while the third axis is longer (O1-Cu-O1'). On the other hand, three (rhombic) signals (g(1) 2.289, g(2) 2.163, g(3) 2.086) in the room temperature EPR spectrum of 2 suggest three different axes in the coordination octahedron. In the EPR spectrum, of the second trans complex 3, a slightly rhombically distorted elongated axial spectrum is found. The 115 K EPR spectra of the two trans complexes 2 and 3 do not differ significantly from the features observed at room temperature. These results indicate that there is not always a straightforward correlation between the results of XRD structure analysis and EPR spectroscopy. Nevertheless, both methods can act also complementarily and give a deeper insight into the nature of copper(II) chromophores Y1 - 2005 ER - TY - JOUR A1 - Wenzel, Barbara A1 - Wehse, Burkhard A1 - Schilde, Uwe A1 - Strauch, Peter T1 - 1,2-Dithioquadratato- und 1,2-Dithiooxalatoindate(III) = 1,2-dithiosquarato- and 1,2-dithiooxalatoindates(III) N2 - Indium(III) chloride forms in water with potassium 1,2-dithiooxalate (dto) and potassium 1,2-dithiosquarate (dtsq) stable coordination compounds. Due to the higher bridging ability of the 1,2-dithiooxalate ligand in all cases only thiooxalate bridged binuclear complexes were found. From 1,2-dithioquadratate with an identical donor atom set mononuclear trischelates could be isolated. Five crystalline complexes, (BzlMe(3)N)(4)[(dto)(2)In(dto)In(dto)(2)] (1), (BzlPh(3)P)(4)[(dto)(2)In(dto)In(dto)(2)] (2), (BzlMe(3)N)(3)[In(dtsq)(3)] (3), (Bu4N)(3)[In(dtsq)(3)] (4) and (Ph4P)[In(dtsq)(2)(DMF)(2)] (5), have been isolated and characterized by X-ray analyses. Due to the type of the complex and the cations involved these compounds crystallize in different space groups with the following parameters: 1, monoclinic in P2(1)/c with a = 14.4035(5) Angstrom, b = 10.8141(5) Angstrom, c = 23.3698(9) Angstrom, beta = 124.664(2)degrees, and Z = 2; 2, triclinic in P (1) over bar with a = 11.3872(7) Angstrom, b = 13.6669(9) Angstrom, c = 17.4296(10) Angstrom, alpha = 88.883(5)degrees, beta = 96.763(1)degrees, gamma = 74.587(5)degrees, and Z = 1; 3, hexagonal in R3 with a = 20.6501(16) Angstrom, b = 20.6501(16) Angstrom, c = 19.0706(13) Angstrom and Z = 6; 4, monoclinic in P21/c with a = 22.7650(15) Angstrom, b = 20.4656(10) Angstrom, c = 14.4770(9) Angstrom, P Y1 - 2004 UR - http://www3.interscience.wiley.com/cgi-bin/jissue/109594384 ER - TY - JOUR A1 - Secker, Christian A1 - Brosnan, Sarah M. A1 - Limberg, Felix Rolf Paul A1 - Braun, Ulrike A1 - Trunk, Matthias A1 - Strauch, Peter A1 - Schlaad, Helmut T1 - Thermally Induced Crosslinking of Poly(N-Propargyl Glycine) JF - Macromolecular chemistry and physics N2 - As polypeptoids become increasingly popular, they present a more soluble and processable alternative to natural and synthetic polypeptides; the breadth of their potential functionality slowly comes into focus. This report analyzes the ability of an alkyne-functionalized polypeptoid, poly(N-propargyl glycine), to crosslink upon heating. The crosslinking process is analyzed by thermal analysis (differential scanning calorimetry and thermogravimetric analysis), Fourier-transform infrared, electron paramagnetic resonance, and solid-state NMR spectroscopy. While a precise mechanism cannot be confidently assigned, it is clear that the reaction proceeds by a radical mechanism that exclusively involves the alkyne functionality, which, upon crosslinking, yields alkene and aromatic products. KW - Fourier-transform infrared KW - metal-free crosslinking KW - polypeptoid KW - propargyl KW - solid-state NMR Y1 - 2015 U6 - https://doi.org/10.1002/macp.201500223 SN - 1022-1352 SN - 1521-3935 VL - 216 IS - 21 SP - 2080 EP - 2085 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schwarze, Thomas A1 - Kelling, Alexandra A1 - Müller, Holger A1 - Trautmann, Michael A1 - Klamroth, Tillmann A1 - Baumann, Otto A1 - Strauch, Peter A1 - Holdt, Hans-Jürgen T1 - N-2-Pyridinylmethyl-N '-arylmethyl-diaminomaleonitriles: New Highly Selective Chromogenic Chemodosimeters for Copper(II) JF - Chemistry - a European journal KW - amides KW - chemodosimeter KW - colorimetric detection KW - copper KW - sensors KW - UV KW - Vis spectroscopy Y1 - 2012 U6 - https://doi.org/10.1002/chem.201201731 SN - 0947-6539 VL - 18 IS - 34 SP - 10506 EP - 10510 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Sonnenburg, Kirstin A1 - Adelhelm, Philipp A1 - Antonietti, Markus A1 - Smarsly, Bernd A1 - Nöske, Robert A1 - Strauch, Peter T1 - Synthesis and characterization of SiC materials with hierarchical porosity obtained by replication techniques N2 - Porous silicon carbide monoliths were obtained using the infiltration of preformed SiO2 frameworks with appropriate carbon precursors such as mesophase pitch. The initial SiO2 monoliths possessed a hierarchical pore system, composed of an interpenetrating bicontinuous macropore structure and 13 nm mesopores confined in the macropore walls. After carbonization, further heat treatment at ca. 1400 degrees C resulted in the formation of a SiC-SiO2 composite, which was converted into a porous SiC monolith by post-treatment with ammonium fluoride solution. The resulting porous SiC featured high crystallinity, high chemical purity and showed a surface area of 280 m(2) g(-1) and a pore volume of 0.8 ml g(-1) Y1 - 2006 UR - http://pubs.rsc.org/en/Content/ArticleLanding/2006/CP/b604819f U6 - https://doi.org/10.1039/B604819F ER - TY - JOUR A1 - Strehmel, Veronika A1 - Rexhausen, Hans A1 - Strauch, Peter T1 - 2,2,6,6-Tetramethylpiperidine-1-yloxyl bound to the imidazolium ion by an acetamido group for investigation of ionic liquids N2 - New spin probes bearing the 2,2,6,6-tetramethylpiperidine-1-yloxyl covalently bound to the imidazolium ion via a methylene spacer and an amide group are synthesized. If the anion is bis(trifluoromethylsulfonylimide) instead of iodide, the new spin probe has a similar structure as that of an ionic liquid. Nevertheless, the new spin probes are useful tools to investigate ionic liquids. Y1 - 2010 UR - http://www.sciencedirect.com/science/journal/00404039 U6 - https://doi.org/10.1016/j.tetlet.2009.11.124 SN - 0040-4039 ER -