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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], ...
Aufsatz
Reversible Photo-Induced Reshaping of Imprinted Microstructures Using a Low Molecular Azo Dye
(2022-01-31)
A blend of low molecular azo glass (AZOPD) and polystyrene (PS) were used for the systematic investigation of photo-induced stretching and recovery of nanoimprinted structures. For this purpose, light and heat was used as recovery stimuli. The AZOPD/PS microstructures, fabricated with thermal nanoimprint lithography (tNIL), comprises three different shapes (circles, crosses and squares) and various concentrations of AZOPD fractions. The results show a concentrationdependent reshaping. Particularly the sample with 43 ...
Aufsatz
Reactions of Mesityl Azide with Ferrocene-Based N-Heterocyclic Germylenes, Stannylenes and Plumbylenes, Including PPh₂-Functionalised Congeners
(2022-05-05)
The active PbII/P Lewis pair nature of a PPh₂-functionalised ferrocene-based N-heterocyclic plumbylene is demonstrated by its reaction with mesityl azide to afford a phosphazide, which is in contrast to the inertness of the unfunctionalised congener. The lighter analogues most likely react with MesN₃ at their respective tetrel atom Eᴵᴵ, leading to the formation of N₂ and an Eᶦᵛ=NMes unit, followed by NMes transfer from the Eᶦᵛ to the Pᴵᴵᴵ atom.
The reactivity of ferrocene-based N-heterocyclic tetrylenes ...
Aufsatz
Asymmetrically Substituted Phospholes as Ligands for Coinage Metal Complexes
(2022-05-24)
A series of coinage metal complexes asymmetrically substituted 2,5-diaryl phosphole ligands is reported. Structure, identity, and purity of all obtained complexes were corroborated with state-of-the-art techniques (multinuclear NMR, mass spectrometry, elemental analysis, X-ray diffraction) in solution and solid state. All complexes obtained feature luminescence in solution as well as in the solid state. Additionally, DOSY-MW NMR estimation experiments were performed to achieve information about the aggregation behavior ...
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Synthesis of Geminal Bis- and Tetrakisphosphonate Ester Derivatives and Their Coordination Behavior Towards Ca(II) Ions
(2022-04-05)
Geminal Bisphosphonate (BP) Esters in Ca(II) Ion Coordination. A series of geminal BPs was prepared starting from their corresponding ethyl- or isopropyl (arylmethylene)phosphonate ester precursors. Complexation with CaCl₂ yields the derived coordination compounds [Ca(H₂O)₂(L1–L3)₂]Cl₂ or [Ca(L8)Cl₂]ₙ. Their structures in the solid- (SCXRD) as well as solution-state (¹H DOSY NMR) are evaluated and comprehensively compared to literature data.
The preparation and thorough characterization of a variety of (arylmethy ...
Aufsatz
Application of mixed-effects modelling and rule-based models to explain copper variation in soil profiles of southern Germany
(2022-05-25)
Copper (Cu) is an essential element for plants and microorganisms and at larger concentrations a toxic pollutant. A number of factors controlling Cu dynamics have been reported, but information on quantitative relationships is scarce. We aimed to (i) quantitatively describe and predict soil Cu concentrations (CuAR) in aqua regia considering site-specific effects and effects of pH, soil organic carbon (SOC) and cation exchange capacity (CEC), and (ii) study the suitability of mixed-effects modelling and rule-based ...
Aufsatz
Amplified Spontaneous Emission in Paper
(2019-02-12)
Industrially produced copy paper is presented as a novel optical material for narrow-band stimulated emission. Fluorescent brightening agents (FBA) such as Calcofluor White provide enough gain to exceed the threshold for amplified spontaneous emission. By applying an additional dye such as Coumarin 307, or simply a highlighter pen, the emission line can be shifted from blue (~440 nm), towards turquoise (>480 nm), up to orange (590 nm) which can be useful for spectroscopic applications. These properties are demonstrated ...
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Spatial and Temporal Variations of Stable Isotopes in Precipitation in the Mountainous Region, North Hesse
(2022-12-01)
Patterns of stable isotopes of water (¹⁸O and ²H) in precipitation have been used as tracers for analyzing environmental processes which can be changed by factors such as the topography or meteorological variables. In this study, we investigated the isotopic data in precipitation for one year in the low mountain range of North Hesse, Germany, and analyzed mainly for altitude, rainfall amount, and air temperature effects on a regional scale. The results indicate that the isotopic composition expressed an altitude ...
Aufsatz
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
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 ...