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131.
The nature of protein crystals is discussed. Since protein crystals contain not only proteins but also other substances the usage of conventional terms (of industrial crystallization) of naming such crystals is questioned. The proof that there are other components than the protein itself in a protein crystal is given. It is suggested to use a procedure like in biotechnology to guarantee the production of the right protein crystals according to the PAT concept. It is suggested not to use other established names like “hydrates”, “solvates”, “but crystals for proteins since the definitions do not fit the nature of the protein crystals. 相似文献
132.
Myung-Joon Jeong Kyu-Young Kang Markus Bacher Hyoung-Jin Kim Byoung-Muk Jo Antje Potthast 《Cellulose (London, England)》2014,21(6):4621-4632
Hanji paper, the paper material traditionally used in Korea, is in the focus of the present aging and mechanistic study. As raw materials and historic recipes for paper making are still available for Hanji today, specimen resembling historical material at the point of production can be prepared. While from that starting point, historical material had taken the path of natural aging, newly prepared samples—prepared according to both historic and current recipes—were artificially aged, and both aging modes can be compared. For the first time, an in-depth chemical and mathematical analysis of the aging processes for Hanji is presented. The aging of Hanji paper, resulting in hydrolysis and oxidation processes, was addressed by means of selective fluorescene labeling of oxidized groups in combination with gel permeation chromatography, providing profiles of carbonyl and carboxyl groups relative to the molar mass distribution. Starting Hanji showed the highest molecular weight (>1,400 kDa) ever reported for paper. We have defined two critical parameters for comparison of the paper samples: half-life DP (the time until every chain is split once on average) and life expectancy (the time until an average DP of failure is reached and no further mechanical stress can be tolerated). The two values were determined to be approximately 500 and 4,000 years, respectively, for the Hanji samples, provided there is no UV radiation. The rate of cellulose chain scission under accelerated aging (80 °C, RH 65 %), was about 600 times faster than under natural conditions. In addition, cellulose degradation of Hanji paper under accelerated aging condition was about 2–3 times slower than that of historical rag paper as those used in medieval Europe. 相似文献
133.
Dr. Sébastien Prévost Dr. Nathalie Dupré Markus Leutzsch Dr. Qinggang Wang Dr. Vijay Wakchaure Prof. Dr. Benjamin List 《Angewandte Chemie (International ed. in English)》2014,53(33):8770-8773
An asymmetric Torgov cyclization, catalyzed by a novel, highly Brønsted acidic dinitro‐substituted disulfonimide, is described. The reaction delivers the Torgov diene and various analogues with excellent yields and enantioselectivity. This method was applied in a very short synthesis of (+)‐estrone. 相似文献
134.
Andrea Kunfermann Matthias Witschel Boris Illarionov Ren Martin Matthias Rottmann H. Wolfgang Hffken Michael Seet Wolfgang Eisenreich Hans‐Joachim Knlker Markus Fischer Adelbert Bacher Michael Groll Franois Diederich 《Angewandte Chemie (International ed. in English)》2014,53(8):2235-2239
The enzymes of the non‐mevalonate pathway for isoprenoid biosynthesis have been identified as attractive targets with novel modes of action for the development of herbicides for crop protection and agents against infectious diseases. This pathway is present in many pathogenic organisms and plants, but absent in mammals. By using high‐throughput screening, we identified highly halogenated marine natural products, the pseudilins, to be inhibitors of the third enzyme, IspD, in the pathway. Their activity against the IspD enzymes from Arabidopsis thaliana and Plasmodium vivax was determined in photometric and NMR‐based assays. Cocrystal structures revealed that pseudilins bind to an allosteric pocket by using both divalent metal ion coordination and halogen bonding. The allosteric mode of action for preventing cosubstrate (CTP) binding at the active site was elucidated. Pseudilins show herbicidal activity in plant assays and antiplasmodial activity in cell‐based assays. 相似文献
135.
Dr. Peter Thumbs M. Sc. Timm T. Ensfelder M. Sc. Markus Hillmeier Dr. Mirko Wagner M. Sc. Matthias Heiss M. Sc. Constanze Scheel M. Sc. Alexander Schön Dr. Markus Müller Prof. Dr. Stylianos Michalakis Dr. Stefanie Kellner Prof. Dr. Thomas Carell 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(30):12451-12455
136.
Markus Hecht Dr. Pawaret Leowanawat Tabea Gerlach Dr. Vladimir Stepanenko Dr. Matthias Stolte Prof. Dr. Matthias Lehmann Prof. Dr. Frank Würthner 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(39):17232-17238
A new perylene bisimide (PBI), with a fluorescence quantum yield up to unity, self-assembles into two polymorphic supramolecular polymers. This PBI bears four solubilizing acyloxy substituents at the bay positions and is unsubstituted at the imide position, thereby allowing hydrogen-bond-directed self-assembly in nonpolar solvents. The formation of the polymorphs is controlled by the cooling rate of hot monomer solutions. They show distinctive absorption profiles and morphologies and can be isolated in different polymorphic liquid-crystalline states. The interchromophoric arrangement causing the spectral features was elucidated, revealing the formation of columnar and lamellar phases, which are formed by either homo- or heterochiral self-assembly, respectively, of the atropoenantiomeric PBIs. Kinetic studies reveal a narcissistic self-sorting process upon fast cooling, and that the transformation into the heterochiral (racemic) sheetlike self-assemblies proceeds by dissociation via the monomeric state. 相似文献
137.
Dr. Weinan Xing Dr. Shengming Yin Dr. Wenguang Tu Dr. Guanyu Liu Dr. Shuyang Wu Dr. Haojing Wang Prof. Markus Kraft Dr. Guangyu Wu Prof. Rong Xu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(3):1187-1191
A simple solvent ligation effect was successfully used to disrupt the growth of a model compound, Fe[(OH)(O3P(CH2)2CO2H)]⋅H2O (MIL-37), into an extended 2D structure by replacing water with dimethylformamide (DMF) as the solvent during the synthesis. Owing to the lack of −OH group, which provides the corner-sharing (binding) oxygen atoms for the octahedra, an amorphous and porous structure is formed. When Fe3+ is partially replaced by Ni2+, the amorphous structure remains and the resultant binary metal catalyst displays excellent photocatalytic oxygen evolution activity with almost 100 % yield achieved under visible light irradiation using [Ru(bpy)3]2+ as the photosensitizer. This study opens up new possibilities of using the simple solvent effect to synthesize high surface area metal phosphonates for catalytic and other applications. 相似文献
138.
The new scandium(III) carbodiimides Sc2(CN2)3 and Sc2O2(CN2) were prepared by solid-state metathesis reactions between Li2(CN2) and ScCl3 and, regarding Sc2O2(CN2), Sc2O3 was added. The X-ray powder diffraction pattern refinements lead to a trigonal-rhombohedral (R3 c) crystal system for Sc2(CN2)3 and to an orthorhombic (Immm) crystal system for Sc2O2(CN2). The structure of Sc2(CN2)3 is isotypic to the well-known rare earth carbodiimides RE2(CN2)3 with the smaller cations RE = Tm, Yb, and Lu, whereas Sc2O2(CN2) is not isotypic to the known RE2O2(CN2) (RE = Y, La, Ce–Gd, except Pm) compounds. Both crystal structures are represented by layered arrangements of scandium, respectively scandium and oxide, alternating with carbodiimide layers. 相似文献
139.
Dr. Verena K. Gramm Daniel Smets Dr. Ireneus Grzesiak Theresa Block Prof. Dr. Rainer Pöttgen Dr. Markus Suta Prof. Dr. Claudia Wickleder Prof. Dr. Thomas Lorenz Prof. Dr. Uwe Ruschewitz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(12):2726-2734
Anhydrous EuII–acetylenedicarboxylate (EuADC; ADC2− = −O2C-C≡C-CO2−) was synthesized by reaction of EuBr2 with K2ADC or H2ADC in degassed water under oxygen-free conditions. EuADC crystallizes in the SrADC type structure (I41/amd, Z=4) forming a 3D coordination polymer with a diamond-like arrangement of Eu2+ nodes (msw topology including the connecting ADC2− linkers). Deep orange coloured EuADC is stable in air and starts decomposing upon heating in an argon atmosphere only at 440 °C. Measurements of the magnetic susceptibilities (μeff=7.76 μB) and 151Eu Mössbauer spectra (δ=−13.25 mm s−1 at 78 K) confirm the existence of Eu2+ cations. Diffuse reflectance spectra indicate a direct optical band gap of Eg=2.64 eV (470 nm), which is in accordance with the orange colour of the material. Surprisingly, EuADC does not show any photoluminescence under irradiation with UV light of different wavelengths. Similar to SrADC, EuADC exhibits a negative thermal volume expansion below room temperature with a volume expansion coefficient αV=−9.4(12)×10−6 K−1. 相似文献