TY - JOUR A1 - Tentschert, Jutta A1 - Jungnickel, Harald A1 - Reichardt, Philipp A1 - Leube, Peter A1 - Kretzschmar, Bernd A1 - Taubert, Andreas A1 - Luch, A. T1 - Identification of nano clay in composite polymers JF - Surface and interface analysis : an international journal devoted to the development and application of techniques for the analysis surfaces, interfaces and thin films N2 - Industrialized food production is in urgent search for alternative packaging materials, which can serve the requirements of a globalized world in terms of longer product shelf lives, reduced freight weight to decrease transport costs, and better barrier functionality to preserve its freshness. Polymer materials containing organically modified nano clay particles as additives are one example for a new generation of packaging materials with specific barrier functionality to actually hit the market. Clay types used for these applications are aluminosilicates, which belong to the mineral group of phyllosilicates. These consist of nano-scaled thin platelets, which are organically modified with quaternary ammonium compounds acting as spacers between the different clay layers, thereby increasing the hydrophobicity of the mineral additive. A variety of different organically modified clays are already available, and the use as additive for food packaging materials is one important application. To ensure valid risk assessments of emerging nano composite polymers used in the food packaging industry, exact analytical characterization of the organically modified clay within the polymer matrix is of paramount importance. Time-of-flight SIMS in combination with multivariate statistical analysis was used to differentiate modified clay reference materials from another. Time-of-flight SIMS spectra of a reference polymer plate, which contained one specific nano clay composite, were acquired. For each modified clay additive, a set of characteristic diagnostic ions could be identified, which then was used to successfully assign unknown clay additives to the corresponding reference material. Thus, the described methodology could be used to define and characterize nano clay within polymer matrices. Copyright (c) 2014 John Wiley & Sons, Ltd. KW - ToF-SIMS KW - nanoparticles KW - nano clay KW - polymer KW - food contact material Y1 - 2014 U6 - https://doi.org/10.1002/sia.5546 SN - 0142-2421 SN - 1096-9918 VL - 46 SP - 334 EP - 336 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Goebel, Ronald A1 - Hesemann, Peter A1 - Friedrich, Alwin A1 - Rothe, Regina A1 - Schlaad, Helmut A1 - Taubert, Andreas T1 - Modular thiol-ene chemistry approach towards mesoporous silica monoliths with organically modified pore walls JF - Chemistry - a European journal N2 - The surface modification of mesoporous silica monoliths through thiol-ene chemistry is reported. First, mesoporous silica monoliths with vinyl, allyl, and thiol groups were synthesized through a sol-gel hydrolysis-poly-condensation reaction from tetramethyl orthosilicate (TMOS) and vinyltriethoxysilane, allyltriethoxysilane, and (3-mercaptopropyl) trimethoxysilane, respectively. By variation of the molar ratio of the comonomers TMOS and functional silane, mesoporous silica objects containing different amounts of vinyl, allyl, and thiol groups were obtained. These intermediates can subsequently be derivatized through radical photoaddition reactions either with a thiol or an olefin, depending on the initial pore wall functionality, to yield silica monoliths with different pore-wall chemistries. Nitrogen sorption, small-angle X-ray scattering, solid-state NMR spectroscopy, elemental analysis, thermogravimetric analysis, and redox titration demonstrate that the synthetic pathway influences the morphology and pore characteristics of the resulting monoliths and also plays a significant role in the efficiency of functionalization. Moreover, the different reactivity of the vinyl and allyl groups on the pore wall affects the addition reaction, and hence, the degree of the pore-wall functionalization. This report demonstrates that thiol-ene photoaddition reactions are a versatile platform for the generation of a large variety of organically modified silica monoliths with different pore surfaces. KW - mesoporous materials KW - photochemistry KW - sol-gel processes KW - surface chemistry Y1 - 2014 U6 - https://doi.org/10.1002/chem.201403982 SN - 0947-6539 SN - 1521-3765 VL - 20 IS - 52 SP - 17579 EP - 17589 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Thiel, Kerstin A1 - Klamroth, Tillmann A1 - Strauch, Peter A1 - Taubert, Andreas T1 - On the interaction of ascorbic acid and the tetrachlorocuprate ion [CuCl4](2-) in CuCl nanoplatelet formation from an ionic liquid precursor (ILP) JF - Physical chemistry, chemical physics : a journal of European Chemical Societies N2 - The formation of CuCl nanoplatelets from the ionic liquid precursor (ILP) butylpyridinium tetrachlorocuprate [C4Py](2)[CuCl4] using ascorbic acid as a reducing agent was investigated. In particular, electron paramagnetic resonance (EPR) spectroscopy was used to evaluate the interaction between ascorbic acid and the Cu(II) ion before reduction to Cu(I). EPR spectroscopy suggests that the [CuCl4](2-) ion in the neat IL is a distorted tetrahedron, consistent with DFT calculations. Addition of ascorbic acid leads to the removal of one chloride from the [CuCl4](2-) anion, as shown by DFT and the loss of symmetry by EPR. DFT furthermore suggests that the most stable adduct is formed when only one hydroxyl group of the ascorbic acid coordinates to the Cu(II) ion. Y1 - 2011 U6 - https://doi.org/10.1039/c1cp20648f SN - 1463-9076 VL - 13 IS - 30 SP - 13537 EP - 13543 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Mantion, Alexandre A1 - Graf, Philipp A1 - Florea, Ileana A1 - Haase, Andrea A1 - Thuenemann, Andreas F. A1 - Masic, Admir A1 - Ersen, Ovidiu A1 - Rabu, Pierre A1 - Meier, Wolfgang P. A1 - Luch, Andreas A1 - Taubert, Andreas T1 - Biomimetic synthesis of chiral erbium-doped silver/peptide/silica core-shell nanoparticles (ESPN) JF - Nanoscale N2 - Peptide-modified silver nanoparticles have been coated with an erbium-doped silica layer using a method inspired by silica biomineralization. Electron microscopy and small-angle X-ray scattering confirm the presence of an Ag/peptide core and silica shell. The erbium is present as small Er(2)O(3) particles in and on the silica shell. Raman, IR, UV-Vis, and circular dichroism spectroscopies show that the peptide is still present after shell formation and the nanoparticles conserve a chiral plasmon resonance. Magnetic measurements find a paramagnetic behavior. In vitro tests using a macrophage cell line model show that the resulting multicomponent nanoparticles have a low toxicity for macrophages, even on partial dissolution of the silica shell. Y1 - 2011 U6 - https://doi.org/10.1039/c1nr10930h SN - 2040-3364 VL - 3 IS - 12 SP - 5168 EP - 5179 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Xie, Zai-Lai A1 - White, Robin J. A1 - Weber, Jens A1 - Taubert, Andreas A1 - Titirici, Magdalena M. T1 - Hierarchical porous carbonaceous materials via ionothermal carbonization of carbohydrates JF - Journal of materials chemistry N2 - We report on the ionothermal synthesis of porous carbon materials from a variety of carbohydrate precursors (i.e. D-glucose, D-fructose, D-xylose, and starch) using 1-butyl-3-methylimidazolium tetrachloroferrate(III), [Bmim][FeCl(4)] as a reusable solvent and catalyst. The carbon materials derived from these different carbohydrates are similar in terms of particle size and chemical composition, possessing relatively high surface areas from 44 to 155 m(2) g(-1) after ionothermal processing, which can be significantly increased to > 350 m(2) g(-1) by further thermal treatment (e. g. post-carbonization at 750 degrees C). CO(2) and N(2) sorption analysis, combined with Hg intrusion porosimetry, reveals a promising hierarchical pore structuring to these carbon materials. The ionic liquid [Bmim][FeCl(4)] has a triple role: it acts as both a soft template to generate the characterized pore structuring, solvent and as a catalyst resulting in enhanced ionothermal carbon yields. Importantly from a process point of view, the ionic liquid can be successfully recovered and reused. The current work shows that ionothermal synthesis has the potential to be an effective, low cost, and green reusable synthetic route towards sustainable porous carbon materials. Y1 - 2011 U6 - https://doi.org/10.1039/c1jm00013f SN - 0959-9428 VL - 21 IS - 20 SP - 7434 EP - 7442 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Delahaye, Emilie A1 - Xie, Zailai A1 - Schäfer, Andreas A1 - Douce, Laurent A1 - Rogez, Guillaume A1 - Rabu, Pierre A1 - Günter, Christina A1 - Gutmann, Jochen S. A1 - Taubert, Andreas T1 - Intercalation synthesis of functional hybrid materials based on layered simple hydroxide hosts and ionic liquid guests - a pathway towards multifunctional ionogels without a silica matrix? JF - Dalton transactions : a journal of inorganic chemistry, including bioinorganic, organometallic, and solid-state chemistry N2 - Functional hybrid materials on the basis of inorganic hosts and ionic liquids (ILs) as guests hold promise for a virtually unlimited number of applications. In particular, the interaction and the combination of properties of a defined inorganic matrix and a specific IL could lead to synergistic effects in property selection and tuning. Such hybrid materials, generally termed ionogels, are thus an emerging topic in hybrid materials research. The current article addresses some of the recent developments and focuses on the question why silica is currently the dominating matrix used for (inorganic) ionogel fabrication. In comparison to silica, matrix materials such as layered simple hydroxides, layered double hydroxides, clay-type substances, magnetic or catalytically active solids, and many other compounds could be much more interesting because they themselves may carry useful functionalities, which could also be exploited for multifunctional hybrid materials synthesis. The current article combines experimental results with some arguments as to how new, advanced functional hybrid materials can be generated and which obstacles will need to be overcome to successfully achieve the synthesis of a desired target material. Y1 - 2011 U6 - https://doi.org/10.1039/c1dt10841g SN - 1477-9226 VL - 40 IS - 39 SP - 9977 EP - 9988 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Marquardt, Dorothea A1 - Xie, Zailai A1 - Taubert, Andreas A1 - Thomann, Ralf A1 - Janiak, Christoph T1 - Microwave synthesis and inherent stabilization of metal nanoparticles in 1-methyl-3-(3-carboxyethyl)-imidazolium tetrafluoroborate JF - Dalton transactions : a journal of inorganic chemistry, including bioinorganic, organometallic, and solid-state chemistry N2 - The synthesis of Co-NPs and Mn-NPs by microwave-induced decomposition of the metal carbonyls Co-2(CO)(8) and Mn-2(CO)(10), respectively, yields smaller and better separated particles in the functionalized IL 1-methyl-3-(3-carboxyethyl)-imidazolium tetrafluoroborate [EmimCO(2)H][BF4] (1.6 +/- 0.3 nm and 4.3 +/- 1.0 nm, respectively) than in the non-functionalized IL 1-n-butyl-3-methylimidazolium tetrafluoroborate [Bmim][BF4]. The particles are stable in the absence of capping ligands (surfactants) for more than six months although some variation in particle size could be observed by TEM. Y1 - 2011 U6 - https://doi.org/10.1039/c1dt10795j SN - 1477-9226 VL - 40 IS - 33 SP - 8290 EP - 8293 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Farra, Ramzi A1 - Thiel, Kerstin A1 - Winter, Alette A1 - Klamroth, Tillmann A1 - Poeppl, Andreas A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Taubert, Andreas A1 - Strauch, Peter T1 - Tetrahalidocuprates(II)-structure and EPR spectroscopy Part 1: Tetrabromidocuprates(II) JF - New journal of chemistry N2 - Tetrahalidocuprates(II) show a high degree of structural flexibility. We present the results of crystallographic and electron paramagnetic resonance (EPR) spectroscopic analyses of four new tetrabromidocuprate(II) compounds and compare the results with previously reported data. The cations in the new compounds are the sterically demanding benzyltriphenylphosphonium, methyltriphenylphosphonium, tetraphenylphosphonium, and hexadecyltrimethylammonium ions; they were used to achieve a reasonable separation of the paramagnetic Cu(II) ions for EPR spectroscopy. X-Ray crystallography shows that in all four complexes the [CuBr4](2-) units have a distorted tetrahedral coordination geometry which is in agreement with DFT calculations. The EPR hyperfine structure was not resolved. This is due to the exchange broadening resulting from still incomplete separation of the paramagnetic Cu(II) centres. Nevertheless, the principal values of the electron Zeemann tensor (g(parallel to) and g(perpendicular to)) of the complexes could be determined. A correlation of structural (X-ray) parameters with the spin density at the copper centres (DFT) is well reflected in the EPR spectra of the bromidocuprates. This enables the correlation of X-ray and EPR parameters to predict the structure of tetrabromidocuprates in physical states other than the crystalline state. As a result, we provide a method to structurally characterize [CuBr4](2-) in, for example, ionic liquids or in solution, which has important implications for e.g. catalysis or materials science. Y1 - 2011 U6 - https://doi.org/10.1039/c1nj20271e SN - 1144-0546 VL - 35 IS - 12 SP - 2793 EP - 2803 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Graf, Philipp A1 - Mantion, Alexandre A1 - Haase, Andrea A1 - Thuenemann, Andreas F. A1 - Masic, Admir A1 - Meier, Wolfgang P. A1 - Luch, Andreas A1 - Taubert, Andreas T1 - Silicification of peptide-coated silver nanoparticles-A biomimetic soft chemistry approach toward chiral hybrid core-shell materials JF - ACS nano N2 - Silica and silver nanoparticles are relevant materials for new applications in optics, medicine, and analytical chemistry. We have previously reported the synthesis of pH responsive, peptide-templated, chiral silver nanoparticles. The current report shows that peptide-stabilized nanoparticles can easily be coated with a silica shell by exploiting the ability of the peptide coating to hydrolyze silica precursors such as TEOS or TMOS. The resulting silica layer protects the nanoparticles from chemical etching, allows their inclusion in other materials, and renders them biocompatible. Using electron and atomic force microscopy, we show that the silica shell thickness and the particle aggregation can be controlled simply by the reaction time. Small-angle X ray scattering confirms the Ag/peptide@silica core-shell structure. UV-vis and circular dichroism spectroscopy prove the conservation of the silver nanoparticle chirality upon silicification. Biological tests show that the biocompatibility in simple bacterial systems is significantly improved once a silica layer is deposited on the silver particles. KW - peptide-templated materials KW - silver nanoparticles KW - chiral nanoparticles KW - Ag/peptide@SiO(2) nanostructures KW - core-shell structures Y1 - 2011 U6 - https://doi.org/10.1021/nn102969p SN - 1936-0851 VL - 5 IS - 2 SP - 820 EP - 833 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Xie, Zai-Lai A1 - Taubert, Andreas T1 - Thermomorphic behavior of the ionic liquids [C(4)mim][FeCl4] and [C(12)mim][FeCl4] JF - ChemPhysChem : a European journal of chemical physics and physical chemistry N2 - The iron-containing ionic liquids 1-butyl-3-methylimidazolium tetrachloroferrate(III) [C(4)mim][FeCl4] and 1-dodecyl-3-methylimidazolium tetrachloroferrate(III) [C(12)mim][FeCl4] exhibit a thermally induced demixing with water (thermomorphism). The phase separation temperature varies with IL weight fraction in water and can be tuned between 100 degrees C and room temperature. The reversible lower critical solution temperature (LCST) is only observed at IL weight fractions below ca. 35% in water. UV/Vis, IR, and Raman spectroscopy along with elemental analysis prove that the yellow-brown liquid phase recovered after phase separation is the starting IL [C(4)mim][FeCl4] and [C(12)mim][FeCl4], respectively. Photometry and ICP-OES show that about 40% of iron remains in the water phase upon phase separation. Although the process is thus not very efficient at the moment, the current approach is the first example of an LCST behavior of a metal-containing IL and therefore, although still inefficient, a prototype for catalyst removal or metal extraction. KW - imidazolium KW - ionic liquids KW - phase transitions KW - Raman spectroscopy KW - thermomorphism Y1 - 2011 U6 - https://doi.org/10.1002/cphc.201000808 SN - 1439-4235 VL - 12 IS - 2 SP - 364 EP - 368 PB - Wiley-VCH CY - Weinheim ER -