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Single-wall carbon nanotubes-chitosan nanocomposites: Surface wettability, mechanical and thermal properties
(2021-04-14)
Functionalized single-wall carbon nanotubes (f-SWCN) are dispersed in chitosan films by self-assembly of both components in aqueous media. This carbon form is a promising nanofiller to achieve nanocomposites with refined thermal, mechanical and surface features. In this study, we investigated the influence of functionalized single-wall carbon nanotubes concentration on the resulting properties of the nanocomposites structures. Functionalized single-wall carbon nanotubes are dispersed on a molecular scale in the ...
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Polarization Dependent Photoinduced Supramolecular Chirality in High-Performance Azo Materials
(2021-05-11)
Here, we will show photo-induced supramolecular chirality in thin films of achiral amorphous polymers with azo groups in their side-chain. A matter of particular interest is the effect of various film thicknesses on azimuthal rotation and ellipticity of incident/transmitted polarized light. Furthermore, we investigated the temporal stability of inscribed chirality. By polarimetric measurements, we found out that the azimuthal rotation gets higher with layer thickness. In this scope, we were able to measure a very ...
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N-tert-Alkyl-Substituted N-Heterocyclic Carbenes with a 1,1’-Ferrocenediyl Backbone
(2021-12-14)
1,1’-Diaminoferrocene (1) was converted to α-aminonitriles fc[NHC(CN)MeR’]₂ (fc=1,1’-ferrocenediyl; 2 a: R’=Me, 2 b: R’=Ph, 2 c: R’=tBu) by reaction with ketones MeC(O)R’ in the presence of NaCN/HOAc or to the diimine fc(N=CPh₂)₂ (3) by condensation with Ph₂CO. Treatment of 2 a–c or 3 with MeLi furnished fc(NHR)₂ (4 a: R=tBu, 4 b: R=CMe₂Ph, 4 c: R=CMe₂tBu, 4 d: R=CMePh₂) after aqueous work-up. The formylative cyclisation of 4 a–d to fc[(NR)₂CH][BF₄] (5H[BF₄]) was possible only for R=CMe₃ (a) and CMe₂Ph (b). The ...
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Importance of sources of variability, scales and experimental design: A case study about the effects of biochar and slurry application on soil properties in agricultural silty loam soils
(2021-04-17)
In designed experiments, different sources of variability and an adequate scale of measurement need to be considered, but not all approaches in common usage are equally valid. In order to elucidate the importance of sources of variability and choice of scale, we conducted an experiment where the effects of biochar and slurry applications on soil properties related to soil fertility were studied for different designs: (a) for a field-scale sampling design with either a model soil (without natural variability) as an ...
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3D Arrangement of Magnetic Particles in Thin Polymer Films Assisted by Magnetically Patterned Exchange Bias Layer Systems
(2021-10-31)
The possibility to arrange and embed magnetic micro- and nanoparticles in thin polymer film systems using flat magnetically patterned substrate templates is investigated. In contrast to self-organized particle rows forming by applying a homogeneous magnetic field, particles adapt to the magnetic field landscape of the substrate's magnetic pattern prior to polymer crosslinking. Crosslinking then fixes the particle positions in the polymer. The process is tested for composites of hydrophobic polydimethylsiloxane (PDMS) ...
Aufsatz
Phosphetes via Transition Metal Free Ring Closure – Taking the Proper Turn at a Thermodynamic Crossing
(2021-05-10)
A transition metal free route to phosphetes featuring an exocyclic alkene unit is presented. In this approach phosphanides are added to a variety of diynes generating phosphaallylic intermediates which depending on the reaction conditions transform either to phosphetes or the corresponding phospholes. Investigation of the reaction mechanism by combined quantum chemical and experimental means identifies phosphole formation as thermodynamically controlled reaction path, whereas kinetic control furnishes the corresponding ...
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1,1′-Ferrocenylene-Bridged Bis(N-Heterocyclic Olefin) Derivatives
(2021-10-18)
The 1,1′-ferrocenylene (fc)-bridged bis(N-heterocyclic olefin) compounds (IMes=CH)₂fc (1, IMes=1,3-dimesitylimidazolin-2-ylidene) and (IPr=CH)₂fc (2, IPr=1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) were synthesised from (ICH₂)₂fc (3) and the respective N-heterocyclic carbene IMes or IPr. Ligand substitution reactions of 1 and 2 with [BH₃(THF)] afforded the complexes [1(BH₃)₂] and [2(BH₃)₂] as mixtures of the rac- and meso-diastereomers. The new ferrocene derivatives 1–3 and the complexes meso-[1(BH₃)₂], ...
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Recent Progress in Synthesis and Application of Nanosized and Hierarchical Mordenite—A Short Review
(2021-02-26)
Zeolites with their unique properties find applications in various fields, including medicine, agronomy, ecology, production of detergents and drying agents, and in a number of industrial processes. Among zeolites, mordenite is particularly widespread because of its high silica/alumina ratio, which allows it to resist exposure to high temperatures and to acidic gases and liquids. Mordenite is commercially available as a natural mineral and as a synthesized material. This zeolite is mostly used in its synthetic form ...
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Synthesis, Structure and Cu-Phenylacetylide Coordination of an Unsymmetrically Substituted Bulky dppf-Analog
(2021-12-03)
The donor properties of a set of bulky ferrocene based bisphosphanes (Fe(C₅H₄PMes₂)₂ and (C₅H₄PMes₂)Fe(C₅H₄PᵗBu₂ with Mes= mesityl and ᵗBu=tert-butyl) were probed by exploring the NMR parameters of the corresponding selenophosphoranes amended by cyclovoltammetry. The ligand properties were explored in the complexation of copper phenylacetylide which is relevant as intermediate in the Cu(I) catalyzed CO₂ addition to phenylacetylene. Owing to the poor solubility of the resulting complexes their characterization was ...
Aufsatz
Site-specific interrogation of an ionic chiral fragment during photolysis using an X-ray free-electron laser
(2021-08-12)
Short-wavelength free-electron lasers with their ultrashort pulses at high intensities have originated new approaches for tracking molecular dynamics from the vista of specific sites. X-ray pump X-ray probe schemes even allow to address individual atomic constituents with a ‘trigger’-event that preludes the subsequent molecular dynamics while being able to selectively probe the evolving structure with a time-delayed second X-ray pulse. Here, we use a linearly polarized X-ray photon to trigger the photolysis of a ...