Konfigurations-Bestimmung von Isomeren des Methyl 4-O-Acetyl-2.3-O-(1-phenylethyliden)-α-L-rhamnopyranosides/ The Configuration of Isomeres of Methyl 4-O-Acetyl-2,3-O-(1-phenylethylidene)-α-L-rhamnopyranoside

1981 ◽  
Vol 36 (8) ◽  
pp. 997-999 ◽  
Author(s):  
Hermann Lotter ◽  
András Lipták
Keyword(s):  
Crystalline State ◽  
X Ray ◽  
Nmr Data ◽  
First Time

AbstractThe diastereomeric 2,3-O-[2-phenyl-2-methyl-1,3 dioxalanes] of methyl-α-L-rhamno-pyranosides were synthesised for the first time. The stereochemical characterisation was carried out by X-ray analysis. Evaluation of the X-ray data and comparison with NMR data indicated that the same configuration exists in the crystalline state as in solution.

Bleispezies PbX und PbX2 als Brückenliganden in übergangsmetallorganisch geschützten Koordinationsverbindungen/ Leadspecies PbX and PbX2 as Bridging Ligands in Organometallic Protected Coordination Compounds

2002 ◽  
Vol 57 (1) ◽  
pp. 25-42 ◽  
Author(s):  
Peter Rutsch ◽  
Gottfried Huttner
Keyword(s):  
Coordination Compounds ◽  
Dynamic Behaviour ◽  
Disodium Salt ◽  
3D Nmr ◽  
Spectroscopic Techniques ◽  
The Novel ◽  
Bridging Ligands ◽  
X Ray ◽  
Nmr Data ◽  
First Time

The disodium salt Na2[{(CO)5Cr}2Pb(NO3)2], Na2·1, which contains a lead center in a (4+2) coordination mode, reacts with tetraphenylphosphonium halides [Ph4P]X to give the tetrahedral compounds [Ph4P]2[{(CO)5Cr}2PbX2] (X = Cl: 2a; X = Br: 2b; X = I: 2c). Substitution of the nitrate groups of Na2·1 by alcoxides leads to binuclear compounds of the type [{(CO)5Crg2Pb(μ2-OR)2Pb{Cr(CO)5}2]2- (R = Et: 3a; R = n -Pr: 3b; R = i-Pr: 3c; R = Allyl: 3d). NMR experiments show that these dimeric compounds are in equilibrium with the monomeric species [{(CO)5Cr}2PbR]- .Trialkylphosphanes react with Na2·1 to give the neutral phosphane complexes [{(CO)5Cr}2Pb(PR3)2] (R=Me: 4a; R=Et: 4b; R = n-Bu: 4c), which show dynamic behaviour in solution. All of the novel compounds have been characterized by X-ray analysis, as well as by the usual analytic and spectroscopic techniques. 207Pb-NMR data of Cr(CO)5- bound lead species are reported for the first time.

Electrochemical and spectral properties of tris[tetra(15-crown-5)phthalocyaninato]dilutetium(III)

2005 ◽  
Vol 09 (01) ◽  
pp. 1-6 ◽  
Author(s):  
Igor V. Zhukov ◽  
Lyudmila A. Lapkina ◽  
Yuliya G. Gorbunova ◽  
Vladimir E. Larchenko ◽  
Aslan Yu. Tsivadze
Keyword(s):  
Cyclic Voltammetry ◽  
Spectral Properties ◽  
Redox Properties ◽  
X Ray ◽  
H Nmr ◽  
Nmr Data ◽  
Physicochemical Studies ◽  
First Time

Tris[tetra(15-crown-5)phthalocyaninato]dilutetium(III) ( R 4 Pc )3 Lu 2, whose structure had been confirmed earlier by X-ray analysis, was further examined by physicochemical studies. The redox properties of this complex were investigated by cyclic voltammetry. The spectroelectrochemical study of this compound has been performed for the first time. Based on the results obtained and analysis of literature data, an electrochemical criterion related to double- and triple-decker structure of lanthanide phthalocyanines has been proposed. IR and 1 H NMR data are also reported.

scholarly journals Bufadienolides from the Venom of Bufo Bufo gargarizans and Their Enzyme Inhibition Activities and Brine Shrimp Lethality

2018 ◽  
Vol 13 (7) ◽  
pp. 1934578X1801300 ◽  
Author(s):  
Jian Xiao ◽  
Xiang Zhao ◽  
Wan-Tong Zhong ◽  
Fu-Rong Jiao ◽  
Xiao-Ling Wang ◽  
...  
Keyword(s):  
Inhibitory Activity ◽  
Brine Shrimp ◽  
Bufo Bufo ◽  
Positive Control ◽  
Single Crystal Diffraction ◽  
X Ray ◽  
Nmr Data ◽  
Bufo Gargarizans ◽  
First Time ◽  
Potent Inhibitory Activity

A new bufadienolide named dyscinobufotalin (1), along with twenty known bufadienolides (2–21) were isolated from the venom of Bufo bufo gargarizans. Their structures were elucidated by spectroscopic analysis. The absolute configuration of the new natural product 2 was determined by X-ray single crystal diffraction and the complete NMR data for 3 was delivered for the first time. Both compounds 4 and 8 showed comparable α-glucosidase inhibitory activity (IC50 values of 0.25 and 0.26 μM, respectively) to the positive control acarbose (IC50 value of 0.42 μM), and 5 displayed potent inhibitory activity on acetylcholinesterase with an IC50 value of 0.12 μM. Moreover, 5, 8 and 13 presented moderate toxicity against brine shrimp.

Étude structurale d'un C-glycoside insaturé; le tri-O-acétyl-3,4,6-désoxy-2-α-D-thréo-hexéno-2-pyrannosyle benzène

1985 ◽  
Vol 63 (2) ◽  
pp. 491-494 ◽  
Author(s):  
Hélène Gillier-Pandraud ◽  
Rachid Brahmi ◽  
Véronique Bellosta-Dechavanne ◽  
Stanislas Czernecki
Keyword(s):  
Aromatic Ring ◽  
Crystalline State ◽  
Crystallographic Data ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
H Nmr ◽  
Sugar Moiety ◽  
Nmr Data ◽  
Anomeric Carbon

The structure of 3,4,6-tri-O-acetyl-2-deoxy-α-D-threo-hexeno-pyranosyl benzene 1 has been determined by X-ray diffraction methods. Crystals of 1 are orthorhombic, space group P212121 with a = 22.946(10), b = 10.319(6), c = 7.684(4) Å, V = 1819.42 Å3, Z = 4, ρc = 1.27 g cm−3. The sugar moiety exhibits a half-chair 0H5 conformation in which the aromatic ring is quasi-axial. The anomeric carbon has the α. configuration. The comparison of the 1H nmr data with the crystallographic data established that, in solution, the conformation of 1 is very similar to that in the crystalline state.

Tele-Substitution Reactions in the Synthesis of a Promising Class of Antimalarials

2020 ◽  
Author(s):  
Marat Korsik ◽  
Edwin Tse ◽  
David Smith ◽  
William Lewis ◽  
Peter J. Rutledge ◽  
...  
Keyword(s):  
Heterocyclic Ring ◽  
Ring System ◽  
Substitution Reactions ◽  
Laboratory Notebook ◽  
Polar Solvents ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Core ◽  
Nmr Data

<p></p><p>We have discovered and studied a <i>tele</i>substitution reaction in a biologically important heterocyclic ring system. Conditions that favour the <i>tele</i>-substitution pathway were identified: the use of increased equivalents of the nucleophile or decreased equivalents of base, or the use of softer nucleophiles, less polar solvents and larger halogens on the electrophile. Using results from X-ray crystallography and isotope labelling experiments a mechanism for this unusual transformation is proposed. We focused on this triazolopyrazine as it is the core structure of the <i>in vivo </i>active anti-plasmodium compounds of Series 4 of the Open Source Malaria consortium.</p> <p> </p> <p>Archive of the electronic laboratory notebook with the description of all conducted experiments and raw NMR data could be accessed via following link <a href="https://ses.library.usyd.edu.au/handle/2123/21890">https://ses.library.usyd.edu.au/handle/2123/21890</a> . For navigation between entries of laboratory notebook please use file "Strings for compounds in the article.pdf" that works as a reference between article codes and notebook codes, also this file contain SMILES for these compounds. </p><br><p></p>

Diphosphinoazine Rhodium(I) and Iridium(I) Complexes

2006 ◽  
Vol 71 (2) ◽  
pp. 197-206 ◽  
Author(s):  
Martin Pošta ◽  
Jan Čermák ◽  
Pavel Vojtíšek ◽  
Ivana Císařová
Keyword(s):  
Rhodium Complexes ◽  
Iridium Complexes ◽  
X Ray ◽  
First Time

The first rhodium complexes of diphosphinoazines [{RhCl(1,2-η:5,6-η-CH=CHCH2CH2CH=CHCH2CH2)}2 {μ-R2PCH2C(But)=NN=C(But)CH2PR2] (R = Ph, Cy, Pri) were prepared by cleavage of the bridge in chloro(cycloocta-1,5-diene)rhodium(I) dimer, the analogous iridium(I) complexes were also prepared for the first time. The X-ray structures of isostructural rhodium and iridium complexes with bis(dicyclohexylphosphino)pinacoloneazine were determined. Diphosphinoazine ligands in the complexes remained in (Z,Z) configuration bridging two RhCl(C8H12) units.

scholarly journals Quartz Crystallite Size and Moganite Content as Indicators of the Mineralogical Maturity of the Carboniferous Chert: The Case of Cherts from Eastern Asturias (Spain)

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 611
Author(s):  
Celia Marcos ◽  
María de Uribe-Zorita ◽  
Pedro Álvarez-Lloret ◽  
Alaa Adawy ◽  
Patricia Fernández ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Crystallite Size ◽  
Archaeological Sites ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Infrared And Raman Spectroscopy ◽  
First Time ◽  
Geological Formations

Chert samples from different coastal and inland outcrops in the Eastern Asturias (Spain) were mineralogically investigated for the first time for archaeological purposes. X-ray diffraction, X-ray fluorescence, transmission electron microscopy, infrared and Raman spectroscopy and total organic carbon techniques were used. The low content of moganite, since its detection by X-ray diffraction is practically imperceptible, and the crystallite size (over 1000 Å) of the quartz in these cherts would be indicative of its maturity and could potentially be used for dating chert-tools recovered from archaeological sites. Also, this information can constitute essential data to differentiate the cherts and compare them with those used in archaeological tools. However, neither composition nor crystallite size would allow distinguishing between coastal and inland chert outcrops belonging to the same geological formations.

scholarly journals First Report on the Geologic Occurrence of Natural Na–A Zeolite and Associated Minerals in Cretaceous Mudstones of the Paja Formation of Vélez (Santander), Colombia

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 218
Author(s):  
Carlos Alberto Ríos-Reyes ◽  
German Alfonso Reyes-Mendoza ◽  
José Antonio Henao-Martínez ◽  
Craig Williams ◽  
Alan Dyer
Keyword(s):  
Natural Zeolite ◽  
Scanning Electron Micrographs ◽  
Total Sulfur ◽  
Zeolite A ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mineral Phases ◽  
The World ◽  
Porosity And Permeability ◽  
First Time

This study reports for the first time the geologic occurrence of natural zeolite A and associated minerals in mudstones from the Cretaceous Paja Formation in the urban area of the municipality of Vélez (Santander), Colombia. These rocks are mainly composed of quartz, muscovite, pyrophyllite, kaolinite and chlorite group minerals, framboidal and cubic pyrite, as well as marcasite, with minor feldspar, sulphates, and phosphates. Total organic carbon (TOC), total sulfur (TS), and millimeter fragments of algae are high, whereas few centimeters and not biodiverse small ammonite fossils, and other allochemical components are subordinated. Na–A zeolite and associated mineral phases as sodalite occur just beside the interparticle micropores (honeycomb from framboidal, cube molds, and amorphous cavities). It is facilitated by petrophysical properties alterations, due to processes of high diagenesis, temperatures up to 80–100 °C, with weathering contributions, which increase the porosity and permeability, as well as the transmissivity (fluid flow), allowing the geochemistry remobilization and/or recrystallization of pre-existing silica, muscovite, kaolinite minerals group, salts, carbonates, oxides and peroxides. X-ray diffraction analyses reveal the mineral composition of the mudstones and scanning electron micrographs show the typical cubic morphology of Na–A zeolite of approximately 0.45 mμ in particle size. Our data show that the sequence of the transformation of phases is: Poorly crystalline aluminosilicate → sodalite → Na–A zeolite. A literature review shows that this is an unusual example of the occurrence of natural zeolites in sedimentary marine rocks recognized around the world.

scholarly journals The Effect of Surfactant-Modified Montmorillonite on the Cross-Linking Efficiency of Polysiloxanes

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2623
Author(s):  
Monika Wójcik-Bania ◽  
Jakub Matusik
Keyword(s):  
Total Pore Volume ◽  
Cross Linking ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
The Cross ◽  
Chain Lengths ◽  
First Time ◽  
Substituent Influence ◽  
Benzyl Substituent

Polymer–clay mineral composites are an important class of materials with various applications in the industry. Despite interesting properties of polysiloxanes, such matrices were rarely used in combination with clay minerals. Thus, for the first time, a systematic study was designed to investigate the cross-linking efficiency of polysiloxane networks in the presence of 2 wt % of organo-montmorillonite. Montmorillonite (Mt) was intercalated with six quaternary ammonium salts of the cation structure [(CH3)2R’NR]+, where R = C12, C14, C16, and R’ = methyl or benzyl substituent. The intercalation efficiency was examined by X-ray diffraction, CHN elemental analysis, and Fourier transform infrared (FTIR) spectroscopy. Textural studies have shown that the application of freezing in liquid nitrogen and freeze-drying after the intercalation increases the specific surface area and the total pore volume of organo-Mt. The polymer matrix was a poly(methylhydrosiloxane) cross-linked with two linear vinylsiloxanes of different siloxane chain lengths between end functional groups. X-ray diffraction and transmission electron microscopy studies have shown that the increase in d-spacing of organo-Mt and the benzyl substituent influence the degree of nanofillers’ exfoliation in the nanocomposites. The increase in the degree of organo-Mt exfoliation reduces the efficiency of hydrosilylation reaction monitored by FTIR. This was due to physical hindrance induced by exfoliated Mt particles.

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