scholarly journals Combined XRD-paramagnetic 13C NMR spectroscopy of 1,2,3-triazoles for revealing copper traces in a Huisgen click-chemistry cycloaddition. A model case

2019 ◽  
Vol 25 (1) ◽  
pp. 98-106
Author(s):  
Daniel Canseco-González ◽  
José Luis Rodríguez de la O ◽  
José Enrique Herbert-Pucheta
Keyword(s):  
Click Chemistry ◽  
13C Nmr Spectroscopy ◽  
Model Systems ◽  
Paramagnetic Nmr ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction ◽  
Model Case ◽  
Purification Methods ◽  
Paramagnetic Metal ◽  
Torsional Angles

AbstractCopper-catalyzed Alkyne-Azide Cycloaddition (CuAAC) click chemistry robustness has been demonstrated over recent years to produce 1,2,3-triazoles with excellent yields at mild conditions with simple purification methods. However, the consequences of having copper paramagnetic traces in final products, which complicate spectroscopic assignments and can produce inaccurate conclusions, has been scarcely discussed. Herein we present a strategy that combines X-Ray Diffraction (XRD) with 13C- paramagnetic Nuclear Magnetic Resonance spectroscopy, in order to demonstrate the presence of paramagnetic metal traces at standard Huisgen synthesis and purification conditions. We also demonstrate that the derivatization of 1,4-disubstituted-1,2,3-triazoles to produce 1,3,4,-trisubstituted-1,2,3.triazolium salts, promotes an efficient removal of Cu(II/I) moieties. Evidence of paramagnetic metal moieties is given using XRD structural analysis of abnormalities in torsional angles between substituents and the 1,2,3-triazole center, in parallel to 13C- paramagnetic NMR chemical shift and line width analysis. As model systems to demonstrate the importance of characterizing paramagnetic traces, we present the synthesis of novel 1-((3s,5s,7s)-adamantan-1-yl)-4-cyclopropyl-1H-1,2,3-triazole and its derivatized 1-((3s,5s,7s)-adamantan-1-yl)-4-cyclopropyl-3-methyl-1H-[1,2,3]-triazol-3-ium triflate salt.

scholarly journals Synthesis and Characterization of N-Substituted Polyether-Block-Amide Copolymers

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 773
Author(s):  
Jyun-Yan Ye ◽  
Kuo-Fu Peng ◽  
Yu-Ning Zhang ◽  
Szu-Yuan Huang ◽  
Mong Liang
Keyword(s):  
Titanium Isopropoxide ◽  
Decomposition Temperature ◽  
Phenyl Isocyanate ◽  
Cross Linking ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Degradation Temperature ◽  
Melt Polycondensation ◽  
Structural Regularity

A series of N-substituted polyether-block-amide (PEBA-X%) copolymers were prepared by melt polycondensation of nylon-6 prepolymer and polytetramethylene ether glycol at an elevated temperature using titanium isopropoxide as a catalyst. The structure, thermal properties, and crystallinity of PEBA-X% were investigated using nuclear magnetic resonance spectroscopy, Fourier-transform infrared spectroscopy, differential scanning calorimetry, wide angle X-ray diffraction, and thermogravimetric analysis. In general, the crystallinity, melting point, and thermal degradation temperature of PEBA-X% decreased as the incorporation of N-methyl functionalized groups increased, owing to the disruption caused to the structural regularity of the copolymer. However, in N-acetyl functionalized analogues, the crystallinity first dropped and then increased because of a new γ form arrangement that developed in the microstructure. After the cross-linking reaction of the N-methyl-substituted derivative, which has electron-donating characteristics, with poly(4,4′-methylenebis(phenyl isocyanate), the decomposition temperature of the resulting polymer significantly increased, whereas no such improvements could be observed in the case of the electro-withdrawing N-acetyl-substituted derivative, because of the incompleteness of its cross-linking reaction.

scholarly journals Synthesis, Characterization, and Non-Covalent Interactions of Palladium(II)-Amino Acid Complexes

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4331
Author(s):  
David B. Hobart ◽  
Michael A. G. Berg ◽  
Hannah M. Rogers ◽  
Joseph S. Merola
Keyword(s):  
Amino Acid ◽  
High Resolution Mass Spectrometry ◽  
Resonance Spectroscopy ◽  
Spectroscopic Techniques ◽  
X Ray Diffraction ◽  
Amino Acid Complexes ◽  
Acetone Water ◽  
Square Planar ◽  
Non Covalent Interactions ◽  
Covalent Interactions

The reaction of palladium(II) acetate with acyclic amino acids in acetone/water yields square planar bis-chelated palladium amino acid complexes that exhibit interesting non-covalent interactions. In all cases, complexes were examined by multiple spectroscopic techniques, especially HRMS (high resolution mass spectrometry), IR (infrared spectroscopy), and 1H NMR (nuclear magnetic resonance) spectroscopy. In some cases, suitable crystals for single crystal X-ray diffraction were able to be grown and the molecular structure was obtained. The molecular geometries of the products are discussed. Except for the alanine complex, all complexes incorporate water molecules into the extended lattice and exhibit N-H···O and/or O···(HOH)···O hydrogen bonding interactions. The non-covalent interactions are discussed in terms of the extended lattice structures exhibited by the structures.

Organic Crystals in the Tracheids of Torreya Yunnanensis

IAWA Journal ◽  
1996 ◽  
Vol 17 (4) ◽  
pp. 393-403 ◽  
Author(s):  
Yuki Kondo ◽  
Tomoyuki Fujii ◽  
Yoshioki Hayashi ◽  
Atsushi Kato
Keyword(s):  
Phase Contrast ◽  
Growth Ring ◽  
Uv Spectra ◽  
Resonance Spectroscopy ◽  
Organic Crystals ◽  
X Ray Diffraction ◽  
Cinnamic Aldehyde ◽  
X Ray ◽  
Polarised Light ◽  
Contrast Microscopy

Organic crystals were found in tracheid lumina of some samples of Torreya yunnanensis Chen ' L. K. Fu imported from Yunnan, China. Tracheids with crystals were found in short to long tangential bands along the growth ring boundaries. Because the crystals were rapidly dissolved with ethanol and xylene, cross and tangential sections were mounted in de-ionized water without staining and observed by biological, polarised light, and phase-contrast microscopy. The crystals were sublimated under vacuum during routine sample preparation for conventional SEM and only the peripheral parts remained. With the aid of low vacuum-SEM and modified cryo-SEM procedure, the shape of the crystals was revealed. Some were styloid and large enough to fill tracheid lumina, while others were stacked appearing as slates filling tracheid lumina. X-ray diffraction applied to sections and isolated crystals showed that they were single crystals and orientated along the cell wall. UV spectra on isolated crystals and methanol dissolution of crystals suggested that they were composed of phenolic compounds. Crystals that were recrystallized from methanol were analysed by 1H and l3C nuclear magnetic resonance spectroscopy. These two techniques revealed that the major and minor components were o-methoxy cinnamic acid and o-methoxy cinnamic aldehyde.

scholarly journals Assessment of Metabolic Fluxes in the Mouse Brain in Vivo Using 1H-[13C] NMR Spectroscopy at 14.1 Tesla

2015 ◽  
Vol 35 (5) ◽  
pp. 759-765 ◽  
Author(s):  
Lijing Xin ◽  
Bernard Lanz ◽  
gxia Lei ◽  
Rolf Gruetter
Keyword(s):  
Mouse Models ◽  
Mouse Brain ◽  
Conversion Rate ◽  
Tca Cycle ◽  
Compartment Model ◽  
13C Nmr Spectroscopy ◽  
Resonance Spectroscopy ◽  
Metabolic Fluxes ◽  
Short Echo Time

13C magnetic resonance spectroscopy (MRS) combined with the administration of 13C labeled substrates uniquely allows to measure metabolic fluxes in vivo in the brain of humans and rats. The extension to mouse models may provide exclusive prospect for the investigation of models of human diseases. In the present study, the short-echo-time (TE) full-sensitivity 1H-[13C] MRS sequence combined with high magnetic field (14.1 T) and infusion of [U-13C6] glucose was used to enhance the experimental sensitivity in vivo in the mouse brain and the 13C turnover curves of glutamate C4, glutamine C4, glutamate+glutamine C3, aspartate C2, lactate C3, alanine C3, γ-aminobutyric acid C2, C3 and C4 were obtained. A one-compartment model was used to fit 13C turnover curves and resulted in values of metabolic fluxes including the tricarboxylic acid (TCA) cycle flux VTCA (1.05 ± 0.04 μmol/g per minute), the exchange flux between 2-oxoglutarate and glutamate Vx (0.48 ± 0.02 μmol/g per minute), the glutamate-glutamine exchange rate Vgln (0.20 ± 0.02 μmol/g per minute), the pyruvate dilution factor Kdil (0.82 ± 0.01), and the ratio for the lactate conversion rate and the alanine conversion rate VLac/ VAla (10 ± 2). This study opens the prospect of studying transgenic mouse models of brain pathologies.

Preparation and Characterization of a Novel Flame Retardant

2008 ◽  
Vol 47-50 ◽  
pp. 294-297 ◽  
Author(s):  
Xiu Wei Jia ◽  
Min Zhi Rong ◽  
Ming Qiu Zhang
Keyword(s):  
Flame Retardant ◽  
Sol Gel ◽  
Average Molecular Weight ◽  
Regular Structure ◽  
Gel Permeation Chromatography ◽  
Helical Conformation ◽  
Infrared Spectrometry ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction

A novel flame retardant polymethylsilsesquioxane (PMSQ) was successfully obtained via combination of non-hydrolytic and hydrolytic sol-gel routes. Chemical structure of the resultant PMSQ was determined by nuclear magnetic resonance spectroscopy, Fourier-transform infrared spectrometry and powder X-ray diffraction, respectively. All the measurements demonstrated that the product possessed regular structure with chain-to-chain width of 0.87nm and chain thickness of 0.40nm. Weight average molecular weight of PMSQ was measured to be 3.5×105 using gel permeation chromatography. Numerical simulations of the molecular structure suggested that PMSQ should exhibit cis-isotactic configuration and double helical conformation at undisturbed condition.

13C NMR spectroscopy of heterocycles: 3,5-diaryl-4-bromoisoxazoles

2015 ◽  
Vol 21 (5) ◽  
pp. 279-283 ◽  
Author(s):  
Jiayo Yu ◽  
Beatrice Edjah ◽  
Hector Argueta-Gonzalez ◽  
Stephanie Ross ◽  
Patrick Gaulden ◽  
...  
Keyword(s):  
Chemical Shift ◽  
Substituent Effects ◽  
13C Nmr Spectroscopy ◽  
Ring System ◽  
Aryl Group ◽  
Torsion Angles ◽  
Chemical Shift Data ◽  
Molecular Modeling Studies ◽  
Torsional Angles ◽  
Moderate Yield

AbstractA series of 3,5-diarylisoxazoles (1–9) underwent reaction with N-bromosuccinimide in acetic acid to yield the corresponding 3.5-diaryl-4-bromoisoxazoles (1Br–9Br) in low to moderate yield. The X-ray structure of 3-(4-chlorophenyl)-5-phenyl-4-bromoisoxazole showed torsion angles of ~40° and ~36° between the 3- and 5-aryl groups and the central ring system, respectively. Molecular modeling studies predicted the 3,5-phenylisoxazole ring system to be essentially coplanar and the 3,5-diphenyl groups of the 4-bromoisoxazole derivative to be twisted with torsional angles of 50° and 37°, respectively. Carbon-13 nuclear magnetic resonance (13C NMR) data of the 3,5-diaryl-4-bromoisoxazoles were obtained in dimethyl sulfoxide-d6 (DMSO-d6) at 50°C. Plots of the C4 chemical shift data for isoxazoles (1–9) vs. those for 4-bromoisoxazoles (1Br–9Br) showed a good linear correlation (r2 = 0.974) with a slope of 0.96. Substitution on the 3-aryl group had essentially no effect on the chemical shift for C4 of the 4-bromoisoxazole, whereas that on the 5-aryl group showed an excellent correlation with σ+ values. Despite the predicted torsion angle differences, distal transmission of substituent effects in the 4-bromo ring system was essentially analogous to that in the planar 3,5-diarylisoxazoles.

The Anticancer Drug Cisplatin Interacts with the Human Erythrocyte Membrane

2000 ◽  
Vol 55 (5-6) ◽  
pp. 461-466 ◽  
Author(s):  
Mario Suwalsky ◽  
Pedro Hernández ◽  
Fernando Villena ◽  
Carlos P. Sotomayor
Keyword(s):  
Erythrocyte Membrane ◽  
Human Erythrocyte ◽  
Model Systems ◽  
X Ray Diffraction ◽  
Human Erythrocyte Membrane ◽  
X Ray ◽  
Phospholipid Classes ◽  
Functional Membrane ◽  
Dmpc Bilayer ◽  
Outer Monolayer

Drugs which exert their effects by interacting with DNA cause structural and functional membrane alterations which may be essential for growth inhibition by these agents. This paper describes the interaction of cisplatin with the human erythrocyte membrane and models constituted by bilayers of dimyristoylphosphatidylethanolamine (DMPE) and diacylphosphatidylserine (DAPS), representative of phospholipid classes located in the inner monolayer of the erythrocyte membrane, and of dimyristoylphosphatidylcholine (DMPC), a class present in its outer monolayer. Cisplatin ability to perturb DMPE, DAPS and DMPC bilayer structures was determined by X-ray diffraction and fluorescence spectroscopy. Electron microscopy disclosed that human erythrocytes incubated with 35 μм cisplatin, which is its therapeutical concentration in serum, developed cup-shaped forms (stomatocytes). According to the bilayer couple hypothesis, this means that the drug is inserted into the inner monolayer of the erythrocyte membrane, a conclusion supported by the studies on model systems.

XRD investigation of thermal degradation of some gamma-irradiated polyethylene terephthalate samples

2019 ◽  
Vol 33 (12) ◽  
pp. 1950111 ◽  
Author(s):  
Mihai Todica ◽  
Zoltan Kovacs-Krauss ◽  
Carmen Niculaescu ◽  
Marieta Mureşan-Pop
Keyword(s):  
Thermal Treatment ◽  
Polyethylene Terephthalate ◽  
Structural Changes ◽  
Diffraction Method ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Before And After ◽  
Gamma Irradiated ◽  
Different Doses

The modification of local structure of some commercial polyethylene terephthalate (PET) samples, gamma irradiated at different doses, was investigated by X-ray diffraction method before and after thermal treatment. Before the thermal treatment, the samples exposed to different doses of gamma radiations, does not show noticeable structural changes. However, the gamma exposure affects the thermal behavior of samples submitted to melting–cooling process. These modifications have been highlighted by X-ray diffraction, and confirmed also by thermal analysis and electron spin resonance spectroscopy.

scholarly journals Grafting Hyperbranched Polymers onto TiO2 Nanoparticles via Thiol-yne Click Chemistry and Its Effect on the Mechanical, Thermal and Surface Properties of Polyurethane Coating

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2817 ◽  
Author(s):  
Feng Zhan ◽  
Lei Xiong ◽  
Fang Liu ◽  
Chenying Li
Keyword(s):  
Click Chemistry ◽  
Tio2 Nanoparticles ◽  
Photoelectron Spectroscopy ◽  
Hyperbranched Polymers ◽  
Nanocomposite Coatings ◽  
Mechanical And Thermal Properties ◽  
Nanoparticle Dispersion ◽  
X Ray Diffraction ◽  
X Ray ◽  
Surface Modified

In this study, we proposed a novel and facile method to modify the surface of TiO2 nanoparticles and investigated the influence of the surface-modified TiO2 nanoparticles as an additive in a polyurethane (PU) coating. The hyperbranched polymers (HBP) were grafted on the surface of TiO2 nanoparticles via the thiol-yne click chemistry to reduce the aggregation of nanoparticles and increase the interaction between TiO2 and polymer matrices. The grafting of HBP on the TiO2 nanoparticles surface was investigated by means of X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), nuclear magnetic resonance (NMR) and thermogravimetry analysis (TGA). The thermal and mechanical properties of nanocomposite coatings containing various amounts of TiO2 nanoparticles were measured by dynamic mechanical thermal (DMTA) and tensile strength measurement. Moreover, the surface structure and properties of the newly prepared nanocomposite coatings were examined. The experimental results demonstrate that the incorporation of the surface-modified TiO2 nanoparticles can improve the mechanical and thermal properties of nanocomposite coatings. The results also reveal that the surface modification of TiO2 with the HBP chains improves the nanoparticle dispersion, and the coating surface shows a lotus leaf-like microstructure. Thus, the functional nanocomposite coatings exhibit superhydrophobic properties, good photocatalytic depollution performance, and high stripping resistance.

scholarly journals Structural Characterization of Graphene Oxide: Surface Functional Groups and Fractionated Oxidative Debris

Nanomaterials ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 1180 ◽  
Author(s):  
Elvin Aliyev ◽  
Volkan Filiz ◽  
Muntazim M. Khan ◽  
Young Joo Lee ◽  
Clarissa Abetz ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Graphene Oxide ◽  
Functional Groups ◽  
Structural Model ◽  
Oxide Surface ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction ◽  
Surface Functional Groups ◽  
X Ray ◽  
Transmission Electron

The purpose of this work is the structural analysis of graphene oxide (GO) and by means of a new structural model to answer the questions arising from the Lerf–Klinowski and the Lee structural models. Surface functional groups of GO layers and the oxidative debris (OD) stacked on them were investigated after OD was extracted. Analysis was performed successfully using Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis), X-ray photoemission spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy, solid-state nuclear magnetic resonance spectroscopy (SSNMR), standardized Boehm potentiometric titration analysis, elemental analysis, X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The analysis showed that graphene oxide layers, as well as oxidative debris contain different functional groups such as phenolic –OH, ketone, lactone, carboxyl, quinone and epoxy. Based on these results, a new structural model for GO layers is proposed, which covers all spectroscopic data and explains the presence of the other oxygen functionalities besides carboxyl, phenolic –OH and epoxy groups.

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