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Aufsatz
Tailoring Phospholes for Imprint of Fluorescent 3D Structures
(2019-11-06)
PMMA based polymer blends have been infused with luminescent phospholes and have been structured via nanoimprint. While symmetrically substituted phospholes are prone to crystallization and phase separation, structural modification of the phosphole backbone in the α‐ and β‐positions has been explored, which prevents these issues; a structural explanation for this is suggested. Best phase integrity has been obtained for β‐silyl‐substituted phospholes, which were implemented in thin films and beads. The emission ...
Aufsatz
A simulation-based approach to evaluate objective material parameters from concrete rheometer measurements
(2019-12-31)
Modern concretes such as ultra-high performance concrete (UHPC) show excellent strength properties combined with favorable flow properties. However, the flow properties depend strongly on process parameters during production (temperature, humidity etc.), but also change sensitively even with slight variations in the mixture. In order to ensure desired processing of the fluidlike material and consistent process quality, the flow properties of the concrete must be evaluated quantitatively and objectively. The usual ...
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 ...
Aufsatz
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 ...
Aufsatz
A Stable N-Heterocyclic Silylene with a 1,1′-Ferrocenediyl Backbone
(2020-10-15)
The N-heterocyclic silylene [{Fe(η⁵-C₅H4-NDipp)₂}Si] (1DippSi, Dipp=2,6-diisopropylphenyl) shows an excellent combination of pronounced thermal stability and high reactivity towards small molecules. It reacts readily with CO₂ and N₂O, respectively affording (1DippSiO₂)₂C and (1DippSiO)₂ as follow-up products of the silanone 1DippSiO. Its reactions with H₂O, NH₃, and FcPH₂ (Fc=ferrocenyl) furnish the respective oxidative addition products 1DippSi(H)X (X=OH, NH₂, PHFc). Its reaction with H₃BNH₃ unexpectedly results in ...
Aufsatz
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 ...
Aufsatz
Two-dimensional Wrinkle Resonators for Random Lasing in Organic Glasses
(2020-02-12)
Random lasers consisting of slab waveguides with two-dimensional disordered wrinkling patterns that act as scattering resonators are reported. As active material 2,2′,7,7′-tetraphenyl-9,9′-spirobifluorene is used which is sandwiched between an oxidized silicon wafer and a cladding with higher glass transition temperature. Wrinkles with tailorable periodicity have been induced by thermal annealing. Photopumping experiments show the transition from amplified spontaneous emission to a multiple peak laser spectrum with ...
Aufsatz
Homodinuclear Rhˡ and Irˡ Complexes Derived from Imidazolium-Benzimidazolates
(2020-11-19)
The reactions of [M(μ-Cl)(COD)]2 (M=Rh, Ir) with the conjugated mesomeric betaines 2-(3-methyl-1-imidazolium)-benzimidazolate (1aH), 2-(3-isopropyl-1-imidazolium)-benzimidazolate (1bH) and 2-(3-tert-butyl-1-imidazolium)-benzimidazolate (1cH) in equilibrium with their carbenic tautomers 1’aH, 1’bH and 1’cH were investigated. In the case of 1aH and 1bH, the homodinuclear complexes [MCl(COD){M(μ-1’a)(COD)}] and [MCl(COD){M(μ-1’b)(COD)}] were obtained, whose anionic NHC ligand 1’a− or 1’b− bridges the metal centres in a ...
Aufsatz
Binding of the Human 14-3-3 Isoforms to Distinct Sites in the Leucine-Rich Repeat Kinase 2
(2020-04-07)
Proteins of the 14-3-3 family are well known modulators of the leucine-rich repeat kinase 2 (LRRK2) regulating kinase activity, cellular localization, and ubiquitylation. Although binding between those proteins has been investigated, a comparative study of all human 14-3-3 isoforms interacting with LRRK2 is lacking so far. In a comprehensive approach, we quantitatively analyzed the interaction between the seven human 14-3-3 isoforms and LRRK2-derived peptides covering both, reported and putative 14-3-3 binding sites. ...
Aufsatz
3D Micro/Nanopatterning of a Vinylferrocene Copolymer
(2020-05-23)
In nanoimprint lithography (NIL), a pattern is created by mechanical deformation of an imprint resist via embossing with a stamp, where the adhesion behavior during the filling of the imprint stamp and its subsequent detachment may impose some practical challenges. Here we explored thermal and reverse NIL patterning of polyvinylferrocene and vinylferrocene-methyl methacrylate copolymers to prepare complex non-spherical objects and patterns. While neat polyvinylferrocene was found to be unsuitable for NIL, freshly-prepared ...