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961.
Olaf Reckeweg Falk Lissner Björn Blaschkowski Peter Gross Henning A. Höppe Thomas Schleid 《无机化学与普通化学杂志》2020,646(14):1252-1259
Single-crystalline materials of Li[H2N3C3O3] · 1.75 H2O and Mg[H2N3C3O3]2 · 8 H2O were obtained by dissolving stoichiometric amounts of the respective carbonates with cyanuric acid in boiling water followed by gentle evaporation of excess water after cooling to room temperature. Even though both of these compounds crystallize in the triclinic space group P1 according to X-ray structure analyses of their colorless and transparent single crystals, they adopt two new different structure types. Li[H2N3C3O3] · 1.75 H2O exhibits the unit-cell parameters a = 884.71(6) pm, b = 905.12(7) pm, c = 964.38(7) pm, α = 67.847(2)°, β = 62.904(2)° and γ = 68.565(2)° (Z = 4), whereas the lattice parameters for Mg[H2N3C3O3]2 · 8 H2O are a = 691.95(5) pm, b = 1055.06(8) pm, c = 1183.87(9) pm, α = 85.652(2)°, β = 83.439(2)° and γ = 79.814(2)° (Z = 2). In both cases, the singly deprotonated isocyanuric acid forms monovalent anions consisting of cyclic [H2N3C3O3]– units, which are arranged in ribbons typical for most hitherto known monobasic isocyanurate hydrates. The structures are governed by the oxophilic strength of the respective cation which means that they fulfil their oxophilic coordination requirements either solely with water molecules ([Mg(OH2)6]2+ for Mg2+) or with crystal water and one or two direct coordinative contacts to carbonyl oxygen atoms (O(cy)) of [H2N3C3O3]– anions ([(Li(OH2)2–3(O(cy)1–2]+ for Li+). In both structures occur dominant hydrogen bonds N–H ··· O within the anionic [H2N3C3O3]– ribbons as well as hydrogen bonds O–H ··· O between these ribbons and the hydrated Li+ and Mg2+ cations. 相似文献
962.
Jean-Louis Hoslauer Falk Lissner Björn Blaschkowski Thomas Schleid 《无机化学与普通化学杂志》2020,646(21):1774-1781
The europium(II) oxoborate Li2Eu3Br2[BO3]2 featuring lithium and bromide ions was synthesized by the reaction of Eu2O3 with Li[BH4] as lithium- and boron- as well as EuBr3 as bromide-source at 750 °C for 24 h in silica-jacketed sealed niobium capsules. The yellow, air-stable and yellow fluorescent compound crystallizes in the trigonal space group R3 m (a = 1049.06(7) pm, c = 2993.1(3) pm, c/a = 2.853, Z = 12). The two crystallographically distinguishable Eu2+ cations show either an eightfold coordination as bicapped trigonal prism ([EuO6Br2]12–) or a ninefold coordination as monocapped square antiprism ([EuO5Br4]12–). All oxygen atoms stem from isolated triangular [BO3]3– anions and the Li+ cations reside in octahedral voids provided by both oxygen atoms and Br– anions. 相似文献
963.
964.
On the Mechanism of the Organocatalytic Asymmetric Epoxidation of α,β‐Unsaturated Aldehydes
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Dr. Rebecca L. Davis Dr. Kim L. Jensen Dr. Björn Gschwend Prof. Dr. Karl Anker Jørgensen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(1):64-67
Mechanistic studies on the organocatalytic epoxidation of α,β‐unsaturated aldehydes explore the autoinductive behavior of the reaction and establish that the hydrate/peroxyhydrate of the product is acting as a phase‐transfer catalyst. Based on these studies, an improved methodology that provides high selectivities and decreased catalyst loading, through the addition of chloral hydrate, is developed. 相似文献
965.
966.
The Local Atomic Structures of Liquid CO at 3.6 GPa and Polymerized CO at 0 to 30 GPa from High‐Pressure Pair Distribution Function Analysis
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Dr. Nadine Rademacher Dr. Lkhamsuren Bayarjargal Dr. Wolfgang Morgenroth Prof. Dr. Björn Winkler Dr. Jennifer Ciezak‐Jenkins Dr. Iskander G. Batyrev Dr. Victor Milman 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(36):11531-11539
The local atomic structures of liquid and polymerized CO and its decomposition products were analyzed at pressures up to 30 GPa in diamond anvil cells by X‐ray diffraction, pair distribution function (PDF) analysis, single‐crystal diffraction, and Raman spectroscopy. The structural models were obtained by density functional calculations. Analysis of the PDF of a liquid CO‐rich phase revealed that the local structure has a pronounced short‐range order. The PDFs of polymerized amorphous CO at several pressures revealed the compression of the molecular structure; covalent bond lengths did not change significantly with pressure. Experimental PDFs could be reproduced with simulations from DFT‐optimized structural models. Likely structural features of polymerized CO are thus 4‐ to 6‐membered rings (lactones, cyclic ethers, and rings decorated with carbonyl groups) and long bent chains with carbonyl groups and bridging atoms. Laser heating polymerized CO at pressures of 7 to 9 GPa and 20 GPa resulted in the formation of CO2. 相似文献
967.
Z-Bis(methylthio) and Z-bis(ethylthio)ethene have been prepared in~80% yields by successively adding Z-or E-1,2-dichloroethene (one mol equiv.), and absolute ethanol to a mixture of sodamide (two mol equivalents) and sodium alkanethiolate (two mol equiv.) in liquid ammonia. 相似文献
968.
A Fully Synthetic Four‐Component Antitumor Vaccine Consisting of a Mucin Glycopeptide Antigen Combined with Three Different T‐Helper‐Cell Epitopes
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Dipl.‐Chem. Björn Palitzsch Dipl.‐Chem. Sebastian Hartmann Dipl.‐Chem. Natascha Stergiou Dipl.‐Chem. Markus Glaffig Prof. Dr. Edgar Schmitt Prof. Dr. Horst Kunz 《Angewandte Chemie (International ed. in English)》2014,53(51):14245-14249
In a new concept of fully synthetic vaccines, the role of T‐helper cells is emphasized. Here, a synthetic antitumor vaccine consisting of a diglycosylated tumor‐associated MUC1 glycopeptide as the B‐cell epitope was covalently cross‐linked with three different T‐helper‐cell epitopes via squaric acid ligation of two linear (glyco)peptides. In mice this four‐component vaccine administered without external immune‐stimulating promoters elicit titers of MUC1‐specific antibodies that were about eight times higher than those induced by a vaccine containing only one T‐helper‐cell epitope. The promising results indicate that multiple activation of different T‐helper cells is useful for applications in which increased immunogenicity is required. In personalized medicine, in particular, this flexible construction of a vaccine can serve as a role model, for example, when T‐helper‐cell epitopes are needed that match human leukocyte antigens (HLA) in different patients. 相似文献
969.
A Reversible and Selective Inhibitor of Monoacylglycerol Lipase Ameliorates Multiple Sclerosis
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Dr. Gloria Hernández‐Torres Dr. Mariateresa Cipriano Erika Hedén Emmelie Björklund Dr. Ángeles Canales M. Sc. Debora Zian M. Sc. Ana Feliú Dr. Miriam Mecha Dr. Carmen Guaza Prof. Dr. Christopher J. Fowler Prof. Dr. Silvia Ortega‐Gutiérrez Prof. Dr. María L. López‐Rodríguez 《Angewandte Chemie (International ed. in English)》2014,53(50):13765-13770
Monoacylglycerol lipase (MAGL) is the enzyme responsible for the inactivation of the endocannabinoid 2‐arachidonoylglycerol (2‐AG). MAGL inhibitors show analgesic and tissue‐protecting effects in several disease models. However, the few efficient and selective MAGL inhibitors described to date block the enzyme irreversibly, and this can lead to pharmacological tolerance. Hence, additional classes of MAGL inhibitors are needed to validate this enzyme as a therapeutic target. Here we report a potent, selective, and reversible MAGL inhibitor (IC50=0.18 μM ) which is active in vivo and ameliorates the clinical progression of a multiple sclerosis (MS) mouse model without inducing undesirable CB1‐mediated side effects. These results support the interest in MAGL as a target for the treatment of MS. 相似文献
970.
Inside Back Cover: Almost Enclosed Buckyball Joints: Synthesis,Complex Formation,and Computational Simulations of Pentypticene‐Extended Tribenzotriquinacene (ChemPhysChem 17/2014)
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