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21.
Katharina Röser Bettina Berger Prof. Michael Widhalm Prof. Mario Waser 《ChemistryOpen》2021,10(8):756-759
We herein report an asymmetric protocol to access a series of orthogonally functionalized acyclic chiral target molecules containing a quaternary stereogenic center by carrying out the enantioselective α-alkylation of novel orthogonally functionalized dioxolane-containing cyanoacetates under chiral ammonium salt catalysis. By using just 1 mol % of Maruoka's spirocyclic ammonium salt catalysts enantioselectivities up to e.r.=97.5 : 2.5 could be achieved and further functional group manipulations of the products were carried out as well. 相似文献
22.
Sheida Esmail Tehrani Long Quang Nguyen Giulia Garelli Bettina M. Jensen Tautgirdas Ruzgas Jenny Emnéus Stephan Sylvest Keller 《Electroanalysis》2021,33(12):2516-2528
A highly sensitive amperometric Prussian blue-based hydrogen peroxide sensor was developed using 3D pyrolytic carbon microelectrodes. A 3D printed multielectrode electrochemical cell enabled simultaneous highly reproducible Prussian blue modification on multiple carbon electrodes. The effect of oxygen plasma pre-treatment and deposition time on Prussian blue electrodeposition was studied. The amperometric response of 2D and 3D sensors to the addition of hydrogen peroxide in μM and sub-μM concentrations in phosphate buffer was investigated. A high sensitivity comparable to flow injection systems and a detection limit of 0.16 μM was demonstrated with 3D pyrolytic carbon microelectrodes at stirred batch condition 相似文献
23.
The Activation of Sulfur Hexafluoride at Highly Reduced Low‐Coordinate Nickel Dinitrogen Complexes 下载免费PDF全文
Dipl.‐Chem. Patrick Holze Dipl.‐Chem. Bettina Horn Prof. Dr. Christian Limberg Dipl.‐Chem. Corinna Matlachowski Dr. Stefan Mebs 《Angewandte Chemie (International ed. in English)》2014,53(10):2750-2753
The greenhouse gas sulfur hexafluoride is the common standard example in the literature of a very inert inorganic small molecule that is even stable against O2 in an electric discharge. However, a reduced β‐diketiminate nickel species proved to be capable of converting SF6 into sulfide and fluoride compounds at ambient standard conditions. The fluoride product complex features an unprecedented [NiF]+ unit, where the Ni atom is only three‐coordinate, while the sulfide product exhibits a rare almost linear [Ni(μ‐S)Ni]2+ moiety. The reaction was monitored applying 1H NMR, IR and EPR spectroscopic techniques resulting in the identification of an intermediate nickel complex that gave insight into the mechanism of the eight‐electron reduction of SF6. 相似文献
24.
Artificial Accelerators of the Molecular Chaperone Hsp90 Facilitate Rate‐Limiting Conformational Transitions 下载免费PDF全文
Bettina K. Zierer Matthias Weiwad Martin Rübbelke Lee Freiburger Gunter Fischer Oliver R. Lorenz Michael Sattler Klaus Richter Johannes Buchner 《Angewandte Chemie (International ed. in English)》2014,53(45):12257-12262
The molecular chaperone Hsp90 undergoes an ATP‐driven cycle of conformational changes in which large structural rearrangements precede ATP hydrolysis. Well‐established small‐molecule inhibitors of Hsp90 compete with ATP‐binding. We wondered whether compounds exist that can accelerate the conformational cycle. In a FRET‐based screen reporting on conformational rearrangements in Hsp90 we identified compounds. We elucidated their mode of action and showed that they can overcome the intrinsic inhibition in Hsp90 which prevents these rearrangements. The mode of action is similar to that of the co‐chaperone Aha1 which accelerates the Hsp90 ATPase. However, while the two identified compounds influence conformational changes, they target different aspects of the structural transitions. Also, the binding site determined by NMR spectroscopy is distinct. This study demonstrates that small molecules are capable of triggering specific rate‐limiting transitions in Hsp90 by mechanisms similar to those in protein cofactors. 相似文献
25.
Nature’s Chemical Signatures in Human Olfaction: A Foodborne Perspective for Future Biotechnology 下载免费PDF全文
Andreas Dunkel Martin Steinhaus Matthias Kotthoff Bettina Nowak Dietmar Krautwurst Peter Schieberle Thomas Hofmann 《Angewandte Chemie (International ed. in English)》2014,53(28):7124-7143
The biocatalytic production of flavor naturals that determine chemosensory percepts of foods and beverages is an ever challenging target for academic and industrial research. Advances in chemical trace analysis and post‐genomic progress at the chemistry–biology interface revealed odor qualities of nature’s chemosensory entities to be defined by odorant‐induced olfactory receptor activity patterns. Beyond traditional views, this review and meta‐analysis now shows characteristic ratios of only about 3 to 40 genuine key odorants for each food, from a group of about 230 out of circa 10 000 food volatiles. This suggests the foodborn stimulus space has co‐evolved with, and roughly match our circa 400 olfactory receptors as best natural agonists. This perspective gives insight into nature’s chemical signatures of smell, provides the chemical odor codes of more than 220 food samples, and beyond addresses industrial implications for producing recombinants that fully reconstruct the natural odor signatures for use in flavors and fragrances, fully immersive interactive virtual environments, or humanoid bioelectronic noses. 相似文献
26.
Johannes Maschita Tanmay Banerjee Gkcen Savasci Frederik Haase Christian Ochsenfeld Bettina V. Lotsch 《Angewandte Chemie (International ed. in English)》2020,59(36):15750-15758
Covalent organic frameworks (COFs) are an extensively studied class of porous materials, which distinguish themselves from other porous polymers in their crystallinity and high degree of modularity, enabling a wide range of applications. COFs are most commonly synthesized solvothermally, which is often a time‐consuming process and restricted to well‐soluble precursor molecules. Synthesis of polyimide‐linked COFs (PI‐COFs) is further complicated by the poor reversibility of the ring‐closing reaction under solvothermal conditions. Herein, we report the ionothermal synthesis of crystalline and porous PI‐COFs in zinc chloride and eutectic salt mixtures. This synthesis does not require soluble precursors and the reaction time is significantly reduced as compared to standard solvothermal synthesis methods. In addition to applying the synthesis to previously reported imide COFs, a new perylene‐based COF was also synthesized, which could not be obtained by the classical solvothermal route. In situ high‐temperature XRPD analysis hints to the formation of precursor–salt adducts as crystalline intermediates, which then react with each other to form the COF. 相似文献
27.
28.
Meyer WH Deetlefs M Pohlmann M Scholz R Esterhuysen MW Julius GR Raubenheimer HG 《Dalton transactions (Cambridge, England : 2003)》2004,(3):413-420
A series of palladium, platinum and manganese di(organo)carbene complexes have been prepared from 4-chloro-N-methylquinolinone by processes that involve alkylation before or after attachment to the metal unit; the nucleophilic heteroatoms are separated from the C-donor atom by three bonds. 相似文献
29.
30.
Saskia Biskup Darren J Moore Alexis Rea Bettina Lorenz-Deperieux Candice E Coombes Valina L Dawson Ted M Dawson Andrew B West 《BMC neuroscience》2007,8(1):102