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Ring-Closure Mechanisms Mediated by Laccase to Synthesize Phenothiazines, Phenoxazines, and Phenazines
2020, Hahn, Veronika, Mikolasch, Annett, Weitemeyer, Josephine, Petters, Sebastian, Davids, Timo, Lalk, Michael, Lackmann, Jan-Wilm, Schauer, Frieder
The green and environmentally friendly synthesis of highly valuable organic substances is one possibility for the utilization of laccases (EC 1.10.3.2). As reactants for the herein described syntheses, different o-substituted arylamines or arylthiols and 2,5-dihydroxybenzoic acid and its derivatives were used. In this way, the formation of phenothiazines, phenoxazines, and phenazines was achieved in aqueous solution mediated by the laccase of Pycnoporus cinnabarinus in the presence of oxygen. Two types of phenothiazines (3-hydroxy- and 3-oxo-phenothiazines) formed in one reaction assay were described for the first time. The cyclization reactions yielded C–N, C–S, or C–O bonds. The syntheses were investigated with regard to the substitution pattern of the reaction partners. Differences in C–S and C–N bond formations without cyclization are discussed.
2-hydroxyethylammonium iodide
2014, Kohrt, C., Spannenberg, A., Werner, T.
In the crystal structure of the title salt, C2H 8NO+·I-, N-H⋯O, N-H⋯I and O-H⋯I hydrogen bonds lead to the formation of layers staggered along the c axis.
Single-crystal neutron and X-ray diffraction study of garnet-type solid-state electrolyte Li6La3ZrTaO12: An in situ temperature-dependence investigation (2.5 ≤ T ≤ 873 K)
2021, Redhammer, Günther J., Meven, Martin, Ganschow, Steffen, Tippelt, Gerold, Rettenwander, Daniel
Large single crystals of garnet-type Li6La3ZrTaO12 (LLZTO) were grown by the Czochralski method and analysed using neutron diffraction between 2.5 and 873 K in order to fully characterize the Li atom distribution, and possible Li ion mobility in this class of potential candidates for solid-state electrolyte battery material. LLZTO retains its cubic symmetry (space group Ia 3 d) over the complete temperature range. When compared to other sites, the octahedral sites behave as the most rigid unit and show the smallest increase in atomic displacement parameters and bond length. The La and Li sites show similar thermal expansion in their bond lengths with temperature, and the anisotropic and equivalent atomic displacement parameters exhibit a distinctly larger increase at temperatures above 400 K. Detailed inspection of nuclear densities at the Li1 site reveal a small but significant displacement from the 24d position to the typical 96h position, which cannot, however, be resolved from the single-crystal X-ray diffraction data. The site occupation of LiI ions on Li1 and Li2 sites remains constant, so there is no change in site occupation with temperature. © 2021 International Union of Crystallography. All rights reserved.
Dicyclohexylbis(naphthalen-1-ylmethyl)phosphonium chloride chloroform disolvate
2012, Gowrisankar, S., Neumann, H., Spannenberg, A., Beller, M.
In the title solvated phosphonium salt, C34H40P+·Cl -·2CHCl3, the two cyclohexyl and two 1-naphthylmethyl groups at the P atom are in a distorted tetrahedral arrangement [105.26 (6)-113.35 (6)°]. Both cyclohexyl rings adopt a chair conformation. The dihedral angle between the naphthyl ring systems is 74.08 (3)°.
Synthesis and Characterization of Oxide Chloride Sr2VO3Cl, a Layered S = 1 Compound
2023, Sannes, Johnny A., Kizhake Malayil, Ranjith K., Corredor, Laura T., Wolter, Anja U. B., Grafe, Hans-Joachim, Valldor, Martin
The mixed-anion compound with composition Sr2VO3Cl has been synthesized for the first time, using the conventional high-temperature solid-state synthesis technique in a closed silica ampule under inert conditions. This compound belongs to the known Sr2TmO3Cl (Tm = Sc, Mn, Fe, Co, Ni) family, but with Tm = V. All homologues within this family can be described with the tetragonal space group P4/nmm (No. 129); from a Rietveld refinement of powder X-ray diffraction data on the Tm = V homologue, the unit cell parameters were determined to a = 3.95974(8) and c = 14.0660(4) Å, and the atomic parameters in the crystal structure could be estimated. The synthesized powder is black, implying that the compound is a semiconductor. The magnetic investigations suggest that Sr2VO3Cl is a paramagnet at high temperatures, exhibiting a μeff = 2.0 μB V-1 and antiferromagnetic (AFM) interactions between the magnetic vanadium spins (θCW = −50 K), in line with the V-O-V advantageous super-exchange paths in the V-O layers. Specific heat capacity studies indicate two small anomalies around 5 and 35 K, which however are not associated with long-range magnetic ordering. 35Cl ss-NMR investigations suggest a slow spin freezing below 4.2 K resulting in a glassy-like spin ground state.
Optimizing the Geometry of Photoacoustically Active Gold Nanoparticles for Biomedical Imaging
2020, García-Álvarez, Rafaela, Chen, Lisa, Nedilko, Alexander, Sánchez-Iglesias, Ana, Rix, Anne, Lederle, Wiltrud, Pathak, Vertika, Lammers, Twan, von Plessen, Gero, Kostarelos, Kostas, Liz-Marzán, Luis M., Kuehne, Alexander J.C., Chigrin, Dmitry N.
Photoacoustics is an upcoming modality for biomedical imaging, which promises minimal invasiveness at high penetration depths of several centimeters. For superior photoacoustic contrast, imaging probes with high photothermal conversion efficiency are required. Gold nanoparticles are among the best performing photoacoustic imaging probes. However, the geometry and size of the nanoparticles determine their photothermal efficiency. We present a systematic theoretical analysis to determine the optimum nanoparticle geometry with respect to photoacoustic efficiency in the near-infrared spectral range, for superior photoacoustic contrast. Theoretical predictions are illustrated by experimental results for two of the most promising nanoparticle geometries, namely, high aspect ratio gold nanorods and gold nanostars. Copyright © 2020 American Chemical Society.
Tris(η5-cyclopentadienyl)hafnium(III)
2011, Burlakov, V.V., Arndt, P., Spannenberg, A., Rosenthal, U.
In the crystal structure of the title compound, [Hf(C5H 5)3], three cyclopentadienyl ligands surround the Hf III atom in a trigonal-planar geometry. The molecule lies on a sixfold inversion axis.
Synthesis and crystal structure of a one-dimensional chain-like strontium(II) coordination polymer built of N-methyldiethanolamine and isobutyrate ligands
2021, Seiss, Maximilian, Schmitz, Sebastian, Börner, Martin, Monakhov, Kirill Yu.
The one-dimensional coordination polymer (I) [Sr(ib)2 (H2mda)]n (Hib = isobutyric acid, C4H8O2, and H2mda = N-methyldiethanolamine, C5H13NO2), namely, catena-poly[[(N-methyldiethanolamine-k3O, N, O')strontium(II)]-di-μ2- isobutyrato-K3O, O':O;K3O:O, O'], was prepared by the one-pot aerobic reaction of [Zr6O4 (OH)4 (ib)12 (H2O)].3Hib with Sr(NO3)2 and H2mda in the presence of MnCl2 and Et3N in acetonitrile. The use of MnCl2 is key to the isolation of I as high-quality colorless crystals in good yield. The molecular solid-state structure of I was determined by single-crystal X-ray diffraction. Compound I crystallizes in the monoclinic space group P21/c and shows a one-dimensional polymeric chain structure. Each monomeric unit of this coordination polymer consists of a central SrII ion in the NO8 coordination environment of two deprotonated ib- ligands and one fully protonated H2mda ligand. The C and O atoms of the H2mda ligand were refined as disordered over two sets of sites with site occupancies of 0.619 (3) and 0.381 (3). Compound I shows thermal stability up to 130°C in air. © 2021 International Union of Crystallography. All rights reserved.
Crystal structure of diethyl (E)-2-[(benzofuran-2-yl)methylidene]succinate
2015, Schirmer, Marie-Luis, Spannenberg, Anke, Werner, Thomas
The title compound, C17H18O5, was synthesized by a base-free catalytic Wittig reaction. The molecule consists of a diethyl itaconate unit, which is connected via the C=C double bond to a benzofuran moiety. The benzofuran ring system (r.m.s. deviation = 0.007 Å) forms dihedral angles of 79.58 (4) and 12.12 (10)° with the mean planes through the cis and trans ethoxycarbonyl groups, respectively. An intramolecular C-H...O hydrogen bond involving the O atom of the benzofuran moiety is observed. In the crystal, molecules are linked into ribbons running parallel to the b axis by C-H...O hydrogen bonds.
{N,N-Bis[bis(2,2,2-trifluoroethoxy)phosphanyl]methylamine- κ2 P,P′}bis(η5-cyclopentadienyl) titanium(II)
2013, Haehnel, M., Hansen, S., Spannenberg, A., Beweries, T.
The title compound, [Ti(C5H5)2(C 9H11F12NO4P2)], is a four-membered titanacycle obtained from the reaction of Cp2Ti(η 2-Me3SiC2SiMe3) and CH 3N[P(OCH2CF3)2]2 {N,N-bis[bis(trifluoroethoxy)phosphanyl]methylamine, tfepma}. The Ti II atom is coordinated by two cyclopentadienyl (Cp) ligands and the chelating tfepma ligand in a strongly distorted tetrahedral geometry. The molecule is located on a mirror plane.