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1.
Teobald Kupka Małgorzata A. Broda Piotr P. Wieczorek 《Magnetic resonance in chemistry : MRC》2020,58(6):584-593
The biologically active alkaloid muscimol is present in fly agaric mushroom (Amanita muscaria), and its structure and action is related to human neurotransmitter γ-aminobutyric acid (GABA). The current study reports on determination of muscimol form present in water solution using multinuclear 1H and 13C nuclear magnetic resonance (NMR) experiments supported by density functional theory molecular modeling. The structures of three forms of free muscimol molecule both in the gas phase and in the presence of water solvent, modeled by polarized continuous model, and nuclear magnetic isotropic shieldings, the corresponding chemical shifts, and indirect spin–spin coupling constants were calculated. Several J-couplings observed in proton and carbon NMR spectra, not available before, are reported. The obtained experimental spectra, supported by theoretical calculations, favor the zwitterion form of muscimol in water. This structure differs from NH isomer, previously determined in dimethyl sulfoxide (DMSO) solution. In addition, positions of signals C3 and C5 are reversed in both solvents. 相似文献
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TiCx-PECVD-layers were characterized by TEM. EDX analysis and electron diffraction. TiCx-layers deposited using benzene showed a columnar structure, at which the column size decreases with rising excess carbon content. TiCx-layers deposited using n-heptane presented a lamellar structure, at which the lamellar thickness diminishes with an increasing excess carbon content. In dependence on the layer thickness a periodic progress of the element contents was observed, at which a maximum for Ti and Cl correlates with a minimum for C. It was found that the incorporated chlorine is bonded to titanium. The lattice parameter depends on the chlorine content. Using TiCl4/H2/Ar-gas mixtures without any hydrocarbon, layers containing TiH2 are formed. 相似文献
4.
TheN-(2-phenylethyl)amide of-(1, 1-ethylenedioxy)-ethyl--hydroxybutyric acid (II) and theN-(p-methoxybenzyl)amide of-(1, 1-ethylenedioxy)-ethyl--hydroxybutyric acid (III) have been synthesized and the crystal structure ofIII has been solved. CompoundIII, C16H23O5N, crystallizes in the monoclinic space groupP21/c witha=12.572(2),b=11.149(2),c=12.317(2) Å and=106.53(1)°. The structure was solved by direct methods, and refined by full-matrix least squares to giveR=0.040 (R
w
=0.047) for 2004 intensities. The dioxolane ring has a deformed half-chair conformation. 相似文献
5.
Vasyl' I. Zaremba Dariusz Kaczorowski Galyna P. Nychyporuk Ute Ch. Rodewald Birgit Heying Rainer Pttgen 《无机化学与普通化学杂志》2006,632(6):975-980
New indides Ce3Ge0.66In4.34 and Ce11Ge4.74In5.26 were synthesized from the elements by arc‐melting and subsequent annealing at 870 K. Single crystals were grown through special annealing procedures in sealed tantalum tubes in a high‐frequency furnace. Both compounds were investigated on the basis of X‐ray powder and single crystal data: I4/mcm, La3GeIn4 type, a = 848.8(1), c = 1192.0(2) pm, Z = 4, wR2 = 0.0453, 499 F2 values, 17 variables for Ce3Ge0.66In4.34 and I4/mmm, Sm11Ge4In6 type (ordered version of the Ho11Ge10 type), a = 1199.3(2), c = 1662.0(3) pm, wR2 = 0.0507, 1217 F2 values, 41 variables for Ce11Ge4.74In5.26. The Ce3Ge0.66In4.34 structure shows a mixed Ge/In occupancy on the 4c Wyckoff position. This site is octahedrally coordinated by cerium atoms. These octahedra share all edges, leading to a three‐dimensional network. The latter is penetrated by a two‐dimensional indium substructure which consists of flattened tetrahedra at In–In distances of 291 and 300 pm. The Ce11Ge4.74In5.26 structure contains three crystallographically independent germanium sites. The latter are coordinated by eight or nine cerium neighbors. These CN8 and CN9 polyhedra are condensed to a complex network which is penetrated by a three‐dimensional indium network with In–In distances of 301–314 pm. The 16m site shows a mixed In/Ge occupancy. Chemical bonding in both compounds is dominated by the p elements. Both ternaries studied exhibit localized magnetism due to the presence of Ce3+ ions. The compound Ce3GeIn4 remains paramagnetic down to 1.72 K, whereas Ce11Ge4In6 orders ferromagnetically at TC = 7.5 K. 相似文献
6.
The possible application of the supported liquid membrane (SLM) technique for the extraction of glyphosate is presented. For the extraction of this compound the SLM system has been applied with utilisation of Aliquat 336 as a cationic carrier incorporated into the membrane phase. The extraction efficiency of glyphosate [N-(phosphonomethyl)glycine] is dependent on the donor phase pH, carrier concentration in the organic phase and NaCl concentration in the acceptor phase. The optimal extraction conditions are: donor phase pH>11, acceptor phase of 2 M NaCl solution and the organic phase composed of 20% (w/w) Aliquot 336 solution in di-hexyl ether. Counter-coupled transport of chloride anions from the acceptor phase to the donor phase is a driving force of the mass transfer in this system. 相似文献
7.
Leva S Lichte A Burmeister J Muhn P Jahnke B Fesser D Erfurth J Burgstaller P Klussmann S 《Chemistry & biology》2002,9(3):351-359
Mirror-image oligonucleotide ligands (Spiegelmers) that bind to the pharmacologically relevant target gonadotropin-releasing hormone I (GnRH) with high affinity and high specificity have been identified using the Spiegelmer technology. GnRH is a decapeptide that plays an important role in mammalian reproduction and sexual maturation and is associated with several benign and malignant diseases. First, aptamers that bind to D-GnRH with dissociation constants of 50-100 nM were isolated out of RNA and DNA libraries. The respective enantiomers of the DNA and RNA aptamers were synthesized, and their binding to L-GnRH was shown. These Spiegelmers bind to L-GnRH with similar affinity to that of the corresponding aptamers that bind to D-GnRH. We further demonstrated dose-dependent inhibition of GnRH-induced Ca(2+) release in Chinese hamster ovary cells that were stably transfected with the human GnRH receptor. 相似文献
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9.
Elke Barsties Stefan Schaible Marc-Heinrich Prosenc Ursula Rief Werner Rll Oliver Weyand Birgit Dorer Hans-Herbert Brintzinger 《Journal of organometallic chemistry》1996,520(1-2):63-68
Bis(2-N,N-dimethylamino-indenyl) zirconium dichloride, (2-(CH3)2N-C9H6)2ZrCl2, and dimethylsilyl-bridged bis(2-N,N-dimethylamino-indenyl) zirconium dichloride, (CH3)2Si(2-(CH3)2N-C9H5)2ZrCl2, were prepared by reaction of the corresponding ligand lithium salts with ZrCl4 in toluene. Diffractometric structure determinations reveal C2-symmetric complex geometries for both complexes. An increased electron density at the Zr center of the dimethylamino-substituted complexes is indicated by reduction potentials which are 0.3–0.4 V more negative than those of their unsubstituted analogs. When activated with methyl aluminoxane in toluene solution, (CH3)2Si(2-(CH3)2N-C9H5)2ZrCl2 catalyzes the polymerization of propene to polymers with a microstructure comparable with that of polymers produced with other Me2Si-bridged bis(indenyl)ZrCl2 complexes, but with a substantially increased fraction of i-propyl end groups derived from alkyl exchange between Zr-polymer and Al---Me species. 相似文献
10.
Sabine Hanelt Birgit Braun Stefan Marx Hansjörg A. W. Schneider-Poetsch 《Photochemistry and photobiology》1992,56(5):751-758
We have sequenced cDNA and genomic clones coding for phytochrome of the fern Selaginella. On the amino acid level, this phytochrome shares sequence homologies with phytochromes of higher plants which range between 62 (phytochrome B of Arabidopsis) and 55 (56)% [phytochrome C of Arabidopsis (Avena)]. Introns in the Selaginella gene are short and occupy positions known from phytochrome sequences of higher plants. A rooted phylogenetic tree based on mutation distances puts Selaginella phytochrome closest to the hypothetical ancestor. A similar tree arises if the tree is constructed with partial sequences (about 200 amino acids) around the chromophore attachment site. An extension of this tree by sequences of other cryptogamic plants (Mougeotia, Ceratodon, Psilotum) shows all these sequences including those of the phytochromes B and C of Arabidopsis on a branch, well separated from the branch formed by phytochromes known to accumulate in etiolated plants. The rooted phytochrome phylogenetic tree, however, is difficult to reconcile with the fossil record. 相似文献