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51.
van Gogh AT Nagengast DG Kooij ES Koeman NJ Griessen R 《Physical review letters》2000,84(10):2156-2159
Hydrogen atoms adsorbed on TiO2(110)-(1x1) surfaces have been characterized by scanning tunneling microscopy (STM) combined with electron stimulated desorption (ESD) technique. Certain amounts of H atoms are unexpectedly found on the TiO2 surfaces annealed at 900 K. Two forms of adsorption were discriminated in STM images from the different sensitivity to ESD and tentatively assigned to hydroxyl-type (O-H) and hydride-type (Ti-H) species. 相似文献
52.
I. M. Magin P. A. Purtov A. I. Kruppa T. V. Leshina 《Applied magnetic resonance》2004,26(1-2):155-170
A model is proposed for calculating magnetic field effects formed in a radical triad composed of a biradical and a paramagnetic particle. To describe the influence of the “third” spin on the spin evolution in a biradical, the electron spin exchange interaction of the added spin with one of the paramagnetic centers of the biradical has been considered. Calculating the field dependence of the recombination probability of the biradical-oxygen complex revealed both an increase in recombination probability earlier attributed to spin catalysis and the influence of the values and signs of the exchange interaction in the complex on the shape of the magnetic-field effect dependence. Calculation results are in agreement with the experimental data on the photolysis of 7,7’-dimethyl-silanorbornadiene in aerated and deaerated solution. 相似文献
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54.
Reichenbach-Klinke R Kruppa M König B 《Journal of the American Chemical Society》2002,124(44):12999-13007
The relative positions and conformations of the prosthetic group FAD and the cofactor NADH have been remarkably conserved within the structurally diverse group of flavin enzymes. To provide a chemical rational for such an obviously optimal relative disposition of the redox partners for efficient reaction we have synthesized NADH models with Zn(II)-cyclen substituents for reversible flavin binding in water. Altogether, four of these model systems with systematically varying spacer length between the recognition site and the redox active dihydronicotinamide were prepared. The binding of these model systems to riboflavin tetraacetate was confirmed by potentiometric pH titration in water and their reaction with flavin was followed by UV-vis spectroscopy in aqueous media under physiological conditions. The measurements reveal a significant rate enhancement of up to 175 times that of an intermolecular reaction. Moreover, a strong dependence of the reaction rate on the spacer length was observed, which clearly shows that within the dynamic reversible assembly only the optimal relative disposition of the redox partners ensures an efficient redox reaction. 相似文献
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57.
V. S. Kornievskaya A. I. Kruppa T. V. Leshina 《Journal of inclusion phenomena and macrocyclic chemistry》2008,60(1-2):123-130
It was found that photolysis of N-acyl anthranilic acid methyl ester is very sensitive to solvent nature. This sensitivity was connected with the equilibrium
between intramolecular and intermolecular hydrogen bonding. Also it has been established the glycyrrhizinic acid micelle formation
in water-methanol mixture with CMC about 0.5–1 mM. Solubilization of N-acyl anthranilic acid methyl ester in glycyrrhizinic acid micelles decreases photoreaction efficiency comparing with the
homogeneous solvent. 相似文献
58.
Michael Kruppa und Stefan Ritter haben während ihrer Doktorarbeit zwei Monate am Shanghai Institut of Organic Chemistry in China gearbeitet. 相似文献
59.
Darren Leahy Cameron Grant Alex Jackson Alex Duff Nicholas Tardiota Jessica Van Haeften Xingchen Chen Jonathan M. Peake Michael D. Kruppa Eliot T. Smith David A. Johnson William B. Lott Jonathan M. Harris 《Molecules (Basel, Switzerland)》2021,26(17)
Human neutrophil elastase (HNE) is a uniquely destructive serine protease with the ability to unleash a wave of proteolytic activity by destroying the inhibitors of other proteases. Although this phenomenon forms an important part of the innate immune response to invading pathogens, it is responsible for the collateral host tissue damage observed in chronic conditions such as chronic obstructive pulmonary disease (COPD), and in more acute disorders such as the lung injuries associated with COVID-19 infection. Previously, a combinatorially selected activity-based probe revealed an unexpected substrate preference for oxidised methionine, which suggests a link to oxidative pathogen clearance by neutrophils. Here we use oxidised model substrates and inhibitors to confirm this observation and to show that neutrophil elastase is specifically selective for the di-oxygenated methionine sulfone rather than the mono-oxygenated methionine sulfoxide. We also posit a critical role for ordered solvent in the mechanism of HNE discrimination between the two oxidised forms methionine residue. Preference for the sulfone form of oxidised methionine is especially significant. While both host and pathogens have the ability to reduce methionine sulfoxide back to methionine, a biological pathway to reduce methionine sulfone is not known. Taken together, these data suggest that the oxidative activity of neutrophils may create rapidly cleaved elastase “super substrates” that directly damage tissue, while initiating a cycle of neutrophil oxidation that increases elastase tissue damage and further neutrophil recruitment. 相似文献
60.
Sebastian V. Kruppa Cedric Groß Xin Gui Florian Bäppler Björn Kwasigroch Dr. Yu Sun Prof. Dr. Rolf Diller Prof. Dr. Wim Klopper Prof. Dr. Gereon Niedner-Schatteburg Dr. Christoph Riehn Prof. Dr. Werner R. Thiel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(48):11269-11284
The photoexcitation of a triangular silver(I) hydride complex, [Ag3(μ3-H)(μ2-dcpm)3](PF6)2 ([ P ](PF6)2, dcpm=bis(dicyclohexylphosphino)methane), designed with “UV-silent” bis-phosphine ligands, provokes hydride-to-Ag3 single and double electron transfer. The nature of the electronic transitions has been authenticated by absorption and photodissociation spectroscopy in parallel with high-level quantum-chemical computations utilizing the GW method and Bethe–Salpeter equation (GW-BSE). Specific photofragments of mass-selected [ P ]2+ ions testify to charge transfer and competing pathways resulting from the unique [Ag3(μ3-H)]2+ scaffold. This structural motif of [ P ](PF6)2 has been unequivocally verified by 1H NMR spectroscopy in concert with DFT and X-ray diffraction structural analysis, which revealed short equilateral Ag–Ag distances (dAgAg=3.08 Å) within the range of argentophilic interactions. The reduced radical cation [ P ] . + exhibits strong oxophilicity, forming [ P +O2] .+ ,which is a model intermediate for silver oxidation catalysis. 相似文献