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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
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 ...
Aufsatz
Molecular Basis for Ser/Thr Specificity in PKA Signaling
(2020-06-25)
cAMP-dependent protein kinase (PKA) is the major receptor of the second messenger cAMP and a prototype for Ser/Thr-specific protein kinases. Although PKA strongly prefers serine over threonine substrates, little is known about the molecular basis of this substrate specificity. We employ classical enzyme kinetics and a surface plasmon resonance (SPR)-based method to analyze each step of the kinase reaction. In the absence of divalent metal ions and nucleotides, PKA binds serine (PKS) and threonine (PKT) substrates, ...
Aufsatz
Oxidation Reactions of the N-Heterocyclic Stannylenes [𝘰-C₆H₄ (NSi𝑡BuMe₂)]₂Sn and [{Fe(η⁵ -C₅H₄ -NSi𝑡BuMe₂)₂}Sn] with Sulfur, Selenium, and Diphenyl Diselenide
(2020-01-27)
The N‐heterocyclic stannylenes [{Fe(η$^5$‐C$_5$H$_4$‐NSi𝑡 BuMe$_2$)$_2$}Sn] (1 ) and [𝘰‐C$_6$H$_4$(NSi𝑡 BuMe$_2$)]$_2$Sn (2 ) were prepared in one‐pot reactions from SnCl$_2$, LiN(SiMe$_3$)$_2$, and the corresponding diamine, viz. [Fe(η$^5$‐C$_5$H$_4$‐NHSi𝑡 BuMe$_2$)$_2$] and 𝘰‐C$_6$H$_4$(NSiH𝘵 BuMe$_2$)$_2$, respectively. Oxidative addition reactions of 1 and 2 with S$_8$ and Se$_8$, respectively, afforded the corresponding 1,3,2,4‐dithiadistannetanes ((1 S$_2$), (2 S$_2$)), and 1,3,2,4‐diselenadistannetanes ...
Aufsatz
Cross-π-conjugated enediyne with multioptic metal binding sites
(2020-10-20)
The synthesis of an enediyne molecule functionlized with different metal coordination sites in a cross-pconjugated fashion is reported. Using Pd-mediated cross-coupling reactions, 2,20-bipyridine units were attached at the periphery of diazafluorenemethylidene to obtain a multitopic ligand. UV-vis spectrosopic investigations along with electrochemical analyses reveal electronic communication along the conjugated path reflected in red-shifted absorption spectra and shifts of reduction potentials. The properties of the ...
Aufsatz
Vegetable Crop Biomass Estimation Using Hyperspectral and RGB 3D UAV Data
(2020-10-19)
Remote sensing (RS) has been an e ective tool to monitor agricultural production systems, but for vegetable crops, precision agriculture has received less interest to date. The objective of this study was to test the predictive performance of two types of RS data—crop height information derived from point clouds based on RGB UAV data, and reflectance information from terrestrial hyperspectral imagery—to predict fresh matter yield (FMY) for three vegetable crops (eggplant, tomato, and cabbage). The study was conducted ...
Aufsatz
A Study on the Influence of the Chemical Nature of Fillers on Rheological and Fatigue Behavior of Bitumen Emulsion Mastic
(2020-10-16)
Cold Bitumen Emulsion (CBE) mixture technologies have been recently developed to lower pavement construction temperatures to reduce environmental costs and control gas emissions. Due to its poor early mechanical strength, active fillers (i.e., cement) have been used to obtain high early sti ness in order to have the potential for timely construction of the next layer. There is, however, a lack of understanding about the impact of active fillers on the viscoelastic behavior and fatigue damage resistance of CBE mastics. ...