Professur Koordinationschemie
Koordinationschemie
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Wir freuen uns über ein neues Teammitglied

Masterarbeit begonnen

1-D Koordinationspolymere auf Oberflächen

Daniel Putzky, Masterarbeit 2014

Kooperation mit Prof. Dr. M. Hietschold, Professur Analytik an Festkörperoberflächen

Bachelorarbeit begonnen

Darstellung von porösen Zinnoxid-Nanopartikeln über die simultane Zwilligspolymerisation

Sebastian Selter, Bachelorarbeit 2014

Bachelorarbeit begonnen

Bismuth Containing Polymers

Marius Hirschfeld, Bachelorarbeit 2014

 

Publikationen und Tagungsbeiträge

Salicylate-Functionalized Bismuth Oxido Clusters: Hydrolysis Processes and Microbiological Activity

M. Schlesinger, A. Pathak, S. Richter, D. Sattler, A. Seifert, T. Rüffer, P. C. Andrews, C. A. Schalley, H. Lang, M. Mehring:
Eur. J. Inorg. Chem. 2014, 25, 4218-4227

Abstract Hydrolysis of either Bi(HSal4Me)3 (A) or [Bi22O26(HSal4Me)14](B) in dmso gave the 4-methylsalicylate-substituted bismuth oxido cluster [Bi38O45(HSal4Me)24(dmso)14(H2O)2]4H2O (14H2O), which crystallizes in the triclinic space group Pequation image with cell parameters of a = 20.7214(5), b = 20.9654(6), c = 22.2128(6) , alpha = 100.867(2), beta = 114.108(2), gamma = 107.895(2) and V = 7815.1(4) 3. The hydrolysis of A was studied by using 1H DOSY NMR spectroscopy and electrospray ionization Fourier-transform ion-cyclotron-resonance (ESI-FTICR) mass spectrometry, both of which showed the formation of several larger species under ambient conditions in the presence of moisture. Furthermore, ESI-FTICR MS analysis of cluster B showed the formation of mainly {Bi23O26} species, which indicates the partial dissociation of cluster B in solution. In addition, the three different bismuth species containing 1 (A), 22 (B) or 38 (14H2O) bismuth atoms per molecular formula were tested for their microbiological activity against three strains of Helicobacter pylori (251, 26695 and B128). A minimum inhibitory concentration (MIC) of 6.25 g mL-1 for the mononuclear bismuth complex A was obtained, whereas the bismuth oxido cluster B showed a lower activity with MIC values in the range 25?50.0 ?g?mL?1. The activity of 14H2O is comparable to commercial remedies based on antimicrobial bismuth subsalicylate (BSS; 12.5 g mL-1).
Abstract

Tin Nanoparticles in Carbon / Silica Hybrid Materials by the use of Twin Polymerization

C. Leonhardt, S. Brumm, A. Seifert, A. Lange, S. Csihony, M. Mehring:
ChemPlusChem 2014, DOI: 10.1002/cplu.201402137

Abstract Simultaneous twin polymerization was used to synthesize hybrid materials composed of tin oxide, silica, and a phenolic resin starting from a mixture of 2,2 -spirobi[4H-1,3,2-benzodioxasiline] (Si-spiro) with either the tin(IV) alkoxides 2,2 -spirobi[4H-1,3,2-benzodioxastannine] (A), 2,2 -spirobi[6-methyl-4H-1,3,2-benzodioxastannine] (B), and 2,2 -spirobi[6-methoxy-4H-1,3,2-benzodioxastannine] (C) or the novel tin(II) alkoxides tin(II)-2-(oxidomethyl)-4-methoxyphenolate (D) and tin(II)-2-(oxidomethyl)-5-methoxyphenolate (E). In addition, the twin polymerization of the twin monomer Si-spiro in the presence of tin-containing additives, such as Sn(OtBu)4, Sn(OnBu)2, Sn(OAc)4, and Sn(OAc)2, was investigated for comparison. The as-prepared hybrid materials were characterized using solid-state NMR spectroscopy (13C, 29Si, 119Sn) and high-angle annular dark field scanning transmission electron microscopy, and were finally converted under Ar/H2 atmosphere at 600 C to tin nanoparticles (10-200 nm) in porous carbon/silica hybrid materials (Sn/C/SiO2) with BET surface areas up to 352 m2 g-1.
Abstract

Flash Lamp Annealing of Spray Coated Films Containing Oxidized or Hydrogen Terminated Silicon Nanoparticles

F. Seidel, I. G. Toader, S. Koth, R. Fritzsche, P. Schäfer, D. Bülz, B. Büchter, O. D. Gordan, H. Freitag, A. Jakob, R. Buschbeck, M. Hietschold, H. Lang, M. Mehring, R. Baumann, D. R.T. Zahn:
Thin Solid Films 2014, 562, 282-290

Abstract A variety of silicon nanoparticle (Si NP) powders is studied with diffuse-reflectance infrared Fourier-transform spectroscopy before and after treatment with hydrofluoric acid. As received Si NPs and surface passivated Si NPs are dispersed in organic dispersion media such ethanol. A spray coating system is used to spray the Si NPs onto molybdenum substrates under nitrogen atmosphere. During film growth an in-line spectroscopic ellipsometer monitors the deposition process. In addition, a Xe-lamp enables to flash films in order to melt Si NPs together. Si NP films are then investigated using atomic force microscopy, scanning electron microscopy, and Raman spectroscopy. Eventually, a difference in surface termination (e.g. state of surface oxidation and hydrogen passivation) between Si NP amounts of three selected providers was found. Furthermore, the dispersion stability of Si NP powder in dry ethanol (> 99 %), the film roughness after processing, and the melting of Si NP films is found to depend strongly on the surface termination of the NPs.
Abstract

Microporous Carbon and Mesoporous Silica by use of Twin Polymerization - An integrated Experimental and Theoretical Approach on Precursor Reactivity

P. Kitschke, A. A. Auer, T. Löschner, A. Seifert, S. Spange, T. Rüffer, H. Lang, M. Mehring:
ChemPlusChem 2014, 7, 1009-1023

Abstract Spirocyclic silicon alkoxides were synthesized by reaction of Si(OMe)4 with derivatives of salicylic alcohol and studied by in-situ differential scanning calorimetry with regard to twin polymerization (TP). Both, thermally induced and proton-assisted TP gave nanostructured hybrid materials composed of a phenolic resin and silica. Carbonization and subsequent treatment with HF(aq) resulted in microporous carbon, whereas oxidation in air provided mesoporous silica. DFT calculations were performed to obtain a more detailed insight into the first reaction steps of proton-assisted TP and to support the hypothesis of a reactivity scale based on steric and electronic features of the silicon-containing precursors (twin monomers). The calculated reaction barriers for the initial reaction steps of proton-assisted TP are qualitatively in accordance with the Hammett constants of the substituents at the salicylate moiety. This result offers a simple method to predict the reactivity for twin monomers.
Abstract

The Bismuth Hydrogen Sulfate [Bi2(SO4)2(dmso)8](HSO4)2

L. Wrobel, L. Miersch, M. Schlesinger, T. Rüffer, H. Lang, M. Mehring:
Z. Anorg. Allg. Chem. 2014, 640, 1431-1436

Abstract The reaction of the basic bismuth nitrate [Bi6O4(OH)4(NO3)6]H2O with either thiosalicylic acid or sulfuric acid gave the novel bismuth hydrogen sulfate [Bi2(SO4)2(dmso)8](HSO4)2 (1) (DMSO = dimethyl sulfoxide). The formation of sulfate ions is observed in the presence of either Bi3+ or [Bi6O4(OH)4]6+ indicating bismuth-induced oxidation of thiosalicylic acid. Compound 1 was characterized by elemental analysis, infrared spectroscopy, thermal analysis (TGA), and temperature dependent in situ X-ray powder diffraction. Crystals suitable for single crystal structure analysis were obtained from a DMSO/acetone solution. The title compound 1 crystallizes in the triclinic space group Pequation image with the following lattice parameters: a = 9.5240(4) , b = 9.9535(4) , c = 12.6620(5) , alpha = 109.943(4), beta = 93.952(3), gamma = 102.868(3), V = 1086.17(8) 3, and Z = 1. Analysis of the thermally induced decomposition revealed the formation of Bi2O(SO4)2 and Bi2O2(SO4) as intermediate products and Bi28O32(SO4)10 as final product.
Abstract

Twin Polymerization for the Syntheses of Microporous Carbon and Mesoporous Metal Oxides - Theory and Experiment

P. Kitschke, C. Leonhardt, A. Seifert, S. Spange, A.A. Auer, M. Mehring:
47. Jahrestreffen Deutscher Katalytiker

   
 

Arbeitsgruppenseminar

Raum 205  9:15 Uhr

Felix Dannenberg und Philipp Kitschke

Aktuelle Forschungsergebnisse

22. Sept. 2014

Arbeitsgruppenseminar

Raum 205  9:15 Uhr

Ronny Fritzsche und Benjamin Büchter

Aktuelle Forschungsergebnisse

29. Sept. 2014

 

Prof. Dr. Michael Mehring

Technische Universität Chemnitz
Institut für Chemie
Professur Koordinationschemie
Straße der Nationen 62
D-09111 Chemnitz

E-mail: michael.mehring@...

Tel.: +49 (0) 371 531 - 21250
Fax: +49 (0) 371 531 - 21219

 

Sekretariat: Frau Jutta Ruder
Raum: 1/157
Tel.: +49 (0) 371 531 - 31200
Fax: +49 (0) 371 531 - 21219