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31.
Aamir Iqbal Waidha Humera Khatoon Siddiqui Dr. Yuji Ikeda Dr. Maren Lepple Dr. Sami Vasala Manuel Donzelli Dr. A. D. Fortes Dr. Peter Slater Dr. Blazej Grabowski Dr. Ulrike I. Kramm Dr. Oliver Clemens 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(38):9763-9767
A new vacancy ordered, anion deficient perovskite modification with composition of BaCoO2.67 (Ba3Co3O8□1) has been prepared via a two-step heating process. Combined Rietveld analysis of neutron and X-ray powder diffraction data shows a novel ordering of oxygen vacancies not known before for barium cobaltates. A combination of neutron powder diffraction, magnetic measurements, and density functional theory (DFT) studies confirms G-type antiferromagnetic ordering. From impedance measurements, the electronic conductivity of the order of 10−4 S cm−1 is determined. Remarkably, the bifunctional catalytic activity for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is found to be comparable to that of Ba0.5Sr0.5Co0.8Fe0.2O3–y, confirming that charge-ordered anion deficient non-cubic perovskites can be highly efficient catalysts. 相似文献
32.
Enzymatic Conversion of Flavonoids using Bacterial Chalcone Isomerase and Enoate Reductase 下载免费PDF全文
Dipl.‐Biol. Mechthild Gall Dipl.‐Biochem. Maren Thomsen Dipl.‐Biochem. Christin Peters Dr. Ioannis V. Pavlidis M. Sc. Patrick Jonczyk M. Sc. Philipp P. Grünert Dr. Sascha Beutel Prof. Dr. Thomas Scheper Egon Gross Dr. Michael Backes Dr. Torsten Geißler Dr. Jakob P. Ley Dr. Jens‐Michael Hilmer Dr. Gerhard Krammer Dr. Gottfried J. Palm Prof. Dr. Winfried Hinrichs Prof. Dr. Uwe T. Bornscheuer 《Angewandte Chemie (International ed. in English)》2014,53(5):1439-1442
Flavonoids are a large group of plant secondary metabolites with a variety of biological properties and are therefore of interest to many scientists, as they can lead to industrially interesting intermediates. The anaerobic gut bacterium Eubacterium ramulus can catabolize flavonoids, but until now, the pathway has not been experimentally confirmed. In the present work, a chalcone isomerase (CHI) and an enoate reductase (ERED) could be identified through whole genome sequencing and gene motif search. These two enzymes were successfully cloned and expressed in Escherichia coli in their active form, even under aerobic conditions. The catabolic pathway of E. ramulus was confirmed by biotransformations of flavanones into dihydrochalcones. The engineered E. coli strain that expresses both enzymes was used for the conversion of several flavanones, underlining the applicability of this biocatalytic cascade reaction. 相似文献
33.
Dr. Christoph Kieninger Dr. Klaus Wurst Dr. Maren Podewitz Dr. Maria Stanley Dr. Evelyne Deery Dr. Andrew D. Lawrence Prof. Dr. Klaus R. Liedl Prof. Dr. Martin J. Warren Prof. Dr. Bernhard Kräutler 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(45):20304-20311
The (formal) replacement of Co in cobalamin ( Cbl ) by NiII generates nibalamin ( Nibl ), a new transition-metal analogue of vitamin B12. Described here is Nibl , synthesized by incorporation of a NiII ion into the metal-free B12 ligand hydrogenobalamin ( Hbl ), itself prepared from hydrogenobyric acid ( Hby ). The related NiII corrin nibyric acid ( Niby ) was similarly synthesized from Hby , the metal-free cobyric acid ligand. The solution structures of Hbl , and Niby and Nibl , were characterized by spectroscopic studies. Hbl features two inner protons bound at N2 and N4 of the corrin ligand, as discovered in Hby . X-ray analysis of Niby shows the structural adaptation of the corrin ligand to NiII ions and the coordination behavior of NiII. The diamagnetic Niby and Nibl , and corresponding isoelectronic CoI corrins, were deduced to be isostructural. Nibl is a structural mimic of four-coordinate base-off Cbls , as verified by its ability to act as a strong inhibitor of bacterial adenosyltransferase. 相似文献
34.
35.
Chlorophyll‐Derived Yellow Phyllobilins of Higher Plants as Medium‐Responsive Chiral Photoswitches 下载免费PDF全文
Dr. Chengjie Li Dr. Klaus Wurst Dr. Steffen Jockusch Prof. Karl Gruber Dr. Maren Podewitz Prof. Klaus R. Liedl Prof. Bernhard Kräutler 《Angewandte Chemie (International ed. in English)》2016,55(51):15760-15765
The fall colors are signs of chlorophyll breakdown, the biological process in plants that generates phyllobilins. Most of the abundant natural phyllobilins are colorless, but yellow phyllobilins (phylloxanthobilins) also occur in fall leaves. As shown here, phylloxanthobilins are unique four‐stage photoswitches. Which switching mode is turned on is controlled by the molecular environment. In polar media, phylloxanthobilins are monomeric and undergo photoreversible Z/E isomerization, similar to that observed for bilirubin. Unlike bilirubin, however, the phylloxanthobilin Z isomers photodimerize in apolar solvents by regio‐ and stereospecific thermoreversible [2+2] cycloadditions from self‐assembled hydrogen‐bonded dimers. X‐ray analysis revealed the first stereostructure of a phylloxanthobilin and its hydrogen‐bonded self‐templating architecture, helping to rationalize its exceptional photoswitch features. The chemical behavior of phylloxanthobilins will play a seminal role in identifying biological roles of phyllobilins. 相似文献
36.
The 3 MnIV title compound has been prepared and characterized by X-ray crystallography and magnetochemistry; the complex contains a [Mn(mu-O)2Mn(mu-O)2Mn]4+ core and possesses an S = 3/2 ground state. 相似文献
37.
38.
Rajca A Wang H Pink M Rajca S 《Angewandte Chemie (International ed. in English)》2000,39(24):4481-4483
39.
Marchenko AV Vedernikov AN Dye DF Pink M Zaleski JM Caulton KG 《Inorganic chemistry》2004,43(1):351-360
The reaction of equimolar NO with the 16 electron molecule RuHCl(CO)L(2) (L = P(i)Pr(3)) proceeds, via a radical adduct RuHCl(CO)(NO) L(2), onward to form RuCl(NO)(CO)L(2) (X-ray structure determination) and RuHCl(HNO)(CO)L(2), in a 1:1 mole ratio. The HNO ligand, bound by N and trans to hydride, is rapidly degraded by excess NO. The osmium complex behaves analogously, but the adduct has a higher formation constant, permitting determination of its IR spectrum; both MHCl(CO)(NO)L(2) radicals are characterized by EPR spectroscopy, and DFT calculations on the Ru system show it to have a "half-bent" Ru-N-O unit with the spin density mainly on nitrogen. DFT (PBE) energies rule out certain possible mechanistic steps for forming the two products. A survey of the literature leads to the hypothesis that NO should generally be considered as a (neutral) Lewis base (2-electron donor) when it binds to a 16 electron complex which is resistant to oxidation or reduction, and that the resulting N-centered radical has a M-N-O angle of approximately 140 degrees, which distinguishes it from NO(-) (bent at <140 degrees ) and from NO(+) (>170 degrees ). 相似文献
40.
It is demonstrated that in high quality hydrogenated amorphous silicon films nearly 40% of the contained hydrogen is in the form of hydrogen molecules individually trapped in the amorphous equivalent of tetragonal T sites. The majority of these molecular hydrogens are in the less-clustered component of the contained hydrogen. These results could have major implications for the understanding of light-induced defects and hydrogen mobility. 相似文献