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91.
D. Haristoy S. Mery B. Heinrich L. Mager J. F. Nicoud D. Guillon 《Liquid crystals》2013,40(3):321-328
A series of [1]benzothieno[3,2-b][1]benzothiophene-2,7-dicarboxylate derivatives consisting of a flat, conjugated aromatic moiety containing sulphur hetero-atoms and substituted by terminal chains - ethyl, decyl, Z-4-decenyl or 2-(2-butoxyethoxy)ethyl - has been synthesized. These materials exhibit a smectic liquid crystalline phase, the stability of which was found to be strongly dependent on the length and the nature of the terminal chains. In the mesophase, the molecular arrangement within the smectic layer is characterized by a local stacking of the rigid parts similar to that found in discotic columnar systems. Finally, clear photoconductive behaviour was found in mechanically aligned samples of these liquid crystals. 相似文献
92.
Tao Zhou Silke Richter Ralf Matschat Heinrich Kipphardt 《Accreditation and quality assurance》2013,18(4):341-349
A candidate material for the use as primary standard for silver determination was characterized with respect to total purity. Except the radioactive elements and He, all possible impurities were considered. Based on glow discharge mass spectrometry, inductively coupled plasma-mass spectrometry and carrier gas hot extraction measurements, the demonstrated total purity and its standard uncertainty is w(Ag) = (99.999 52 ± 0.000 11) %. The purity value and its uncertainty is dominated by the contributions from the measurements of the nonmetallic impurities, namely S, N, C and O. 相似文献
93.
94.
Tim Steinke Dr. Patrick Wonner Dr. Richard M. Gauld Dr. Sascha Heinrich Prof. Dr. Stefan M. Huber 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(47):e202200917
Recently, chalcogen bonding has been investigated in more detail in organocatalysis and the scope of activated functionalities continues to increase. Herein, the activation of imines in a Povarov [4+2] cycloaddition reaction with bidentate cationic chalcogen bond donors is presented. Tellurium-based Lewis acids show superior properties compared to selenium-based catalysts and inactive sulfur-based analogues. The catalytic activity of the chalcogen bonding donors increases with weaker binding anions. Triflate, however, is not suitable due to its participation in the catalytic pathway. A solvent screening revealed a more efficient activation in less polar solvents and a pronounced effect of solvent (and catalyst) on endo : exo diastereomeric ratio. Finally, new chiral chalcogen bonding catalysts were applied but provided only racemic mixtures of the product. 相似文献
95.
Sren Arlt Vladana Petkovi Gerd Ludwig Thomas Eichhorn Heinrich Lang Tobias Rüffer Sanja Mijatovi Danijela Maksimovi-Ivani Goran N. Kaluerovi 《Molecules (Basel, Switzerland)》2021,26(7)
Neutral [Ru(η6-arene)Cl2{Ph2P(CH2)3SPh-κP}] (arene = benzene, indane, 1,2,3,4-tetrahydronaphthalene: 2a, 2c and 2d) and cationic [Ru(η6-arene)Cl(Ph2P(CH2)3SPh-κP,κS)]X complexes (arene = mesitylene, 1,4-dihydronaphthalene; X = Cl: 3b, 3e; arene = benzene, mesitylene, indane, 1,2,3,4-tetrahydronaphthalene, and 1,4-dihydronaphthalene; X = PF6: 4a–4e) complexes were prepared and characterized by elemental analysis, IR, 1H, 13C and 31P NMR spectroscopy and also by single-crystal X-ray diffraction analyses. The stability of the complexes has been investigated in DMSO. Complexes have been assessed for their cytotoxic activity against 518A2, 8505C, A253, MCF-7 and SW480 cell lines. Generally, complexes exhibited activity in the lower micromolar range; moreover, they are found to be more active than cisplatin. For the most active ruthenium(II) complex, 4b, bearing mesitylene as ligand, the mechanism of action against 8505C cisplatin resistant cell line was determined. Complex 4b induced apoptosis accompanied by caspase activation. 相似文献
96.
We comment on a Letter by Toytman et al. [Opt. Lett.32, 1941 (2007)] in which a novel setup for wide-field imaging in coherent anti-Stokes Raman scattering (CARS) microscopy is demonstrated. There the authors state that our phase-matching implementation of a wide-field CARS system [Appl. Phys. Lett.84, 816 (2004); New J. Phys.8, 36 (2006)] suffers from a strong background from the bulk medium. However, our results show quite the contrary, i.e., that our setup provides a very good signal contrast, due to an almost vanishing background level from the bulk solvent. 相似文献
97.
Dr. Julian Heinrich Dr. Karolina Bossak-Ahmad Mie Riisom Dr. Haleh H. Haeri Tasha R. Steel Vinja Hergl Alexander Langhans Corinna Schattschneider Jannis Barrera Dr. Stephen M. F. Jamieson Prof. Matthias Stein Prof. Dariush Hinderberger Prof. Christian G. Hartinger Prof. Wojciech Bal Prof. Nora Kulak 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(72):18093-18102
Redox-active Cu(II) complexes are able to form reactive oxygen species (ROS) in the presence of oxygen and reducing agents. Recently, Faller et al. reported that ROS generation by Cu(II) ATCUN complexes is not as high as assumed for decades. High complex stability results in silencing of the Cu(II)/Cu(I) redox cycle and therefore leads to low ROS generation. In this work, we demonstrate that an exchange of the α-amino acid Gly with the β-amino acid β-Ala at position 2 (Gly2→β-Ala2) of the ATCUN motif reinstates ROS production (•OH and H2O2). Potentiometry, cyclic voltammetry, EPR spectroscopy and DFT simulations were utilized to explain the increased ROS generation of these β-Ala2-containing ATCUN complexes. We also observed enhanced oxidative cleavage activity towards plasmid DNA for β-Ala2 compared to the Gly2 complexes. Modifications with positively charged Lys residues increased the DNA affinity through electrostatic interactions as determined by UV/VIS, fluorescence, and CD spectroscopy, and consequently led to a further increase in nuclease activity. A similar trend was observed regarding the cytotoxic activity of the complexes against several human cancer cell lines where β-Ala2 peptide complexes had lower IC50 values compared to Gly2. The higher cytotoxicity could be attributed to an increased cellular uptake as determined by ICP-MS measurements. 相似文献
98.
Stephanie Kindt Prof. Dr. Markus R. Heinrich 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(47):15344-15348
The Meerwein arylation has recently become an even more powerful tool for the functionalization of alkenes. Besides the attachment of an aryl group, radical reactions of this type allow the introduction of several different heteroatoms and a broad variety of alkenes are meanwhile tolerated as substrates. Closing a long‐standing gap of the methodology, this communication describes the first intermolecular Meerwein‐type carbofluorination. In metal‐free reactions, arylalkyl fluorides were obtained from arylhydrazines and alkenes with Selectfluor acting as oxidant and as radical fluorine source. 相似文献
99.
D. Thao Nguyen Matthias Freitag Christian Gutheil Dr. Kai Sotthewes Dr. Bonnie J. Tyler Dr. Marcus Böckmann Mowpriya Das Friederike Schlüter Prof. Dr. Nikos L. Doltsinis Prof. Dr. Heinrich F. Arlinghaus Prof. Dr. Bart Jan Ravoo Prof. Dr. Frank Glorius 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(32):13754-13759
100.
Andrea Preuß Marcus Korb Tobias Rüffer Jörn Bankwitz Colin Georgi Alexander Jakob Stefan E. Schulz Heinrich Lang 《无机化学与普通化学杂志》2020,646(13):670-680
The template synthesis of ethylenediamine ( 1 ) with 2-acetylcyclopentanone ( 2 ) and [Cu(OAc)2 · H2O] ( 5 ) produced [Cu(1-(2-cC5H6(O))C(Me)NCH2)2)] ( 6 ) in 82 % yield. Reaction of 5 with bis(benzoylacetone)diethylenetriamine ( 7 , = L H)[1] gave [Cu(μ-OAc)( L )(H2O)]2 ( 8 ). The solid-state structures of 6 and 8 were determined confirming that 8 possesses intra- and intermolecular hydrogen bonds resulting in a dimer formation. The thermal behavior of 6 – 8 was studied by TG and TG-MS. Under oxygen CuO was formed, whereas under Ar Cu/Cu2O ( 6 ) or Cu ( 8 ) was obtained. Complex 6 was used as CVD precursor for Cu and Cu-oxide deposition (substrate temp., 400–500 °C, N2, 60 mL · min–1; O2, 60 mL · min–1; pressure, 0.87–1.5 mbar). The as-obtained deposits show separated particles of different appearance at the substrate surface as evidenced by SEM. Non-volatile 8 was applied as spin-coating precursor for Cu and CuO formation [conc. 0.25 mol · L–1; volume 0.2 mL; 3000 rpm; depos. time 2 min; heating rate 50 K · min–1; holding time 60 min (Ar), 120 min (air) at 800 °C]. The samples on silicon consist of granulated particles (Ar) or are non-dense with a grainy topography (air). EDX and XPS measurements confirmed the formation of Cu (Ar) or CuO (O2) with up to 13 mol-% C impurity. 相似文献