X Ray Diffraction
Recently Published Documents


TOTAL DOCUMENTS

36391
(FIVE YEARS 6383)

H-INDEX

201
(FIVE YEARS 41)

Synlett ◽  
2021 ◽  
Author(s):  
Jingjing Tang ◽  
Jian Li ◽  
Xue-Yan Yang ◽  
Zhipeng Zhang

A novel class of chiral multidentate ligands have been designed and synthesized from the highly important classic ligand 1,10-phenanthroline (phen) and amino acids. The ligands were proven to be able to coordinate with copper ion by forming a novel chiral copper complex, the structure of which was determined by single crystal X-ray diffraction.


Author(s):  
Mateusz Gołdyn ◽  
Anna Komasa ◽  
Mateusz Pawlaczyk ◽  
Aneta Lewandowska ◽  
Elżbieta Bartoszak-Adamska

The study of various forms of pharmaceutical substances with specific physicochemical properties suitable for putting them on the market is one of the elements of research in the pharmaceutical industry. A large proportion of active pharmaceutical ingredients (APIs) occur in the salt form. The use of an acidic coformer with a given structure and a suitable pK a value towards purine alkaloids containing a basic imidazole N atom can lead to salt formation. In this work, 2,6-dihydroxybenzoic acid (26DHBA) was used for cocrystallization of theobromine (TBR) and caffeine (CAF). Two novel salts, namely, theobrominium 2,6-dihydroxybenzoate, C7H9N4O2 +·C7H5O4 − (I), and caffeinium 2,6-dihydroxybenzoate, C8H11N4O2 +·C7H5O4 − (II), were synthesized. Both salts were obtained independently by slow evaporation from solution, by neat grinding and also by microwave-assisted slurry cocrystallization. Powder X-ray diffraction measurements proved the formation of the new substances. Single-crystal X-ray diffraction studies confirmed proton transfer between the given alkaloid and 26DHBA, and the formation of N—H...O hydrogen bonds in both I and II. Unlike the caffeine cations in II, the theobromine cations in I are paired by noncovalent N—H...O=C interactions and a cyclic array is observed. As expected, the two hydroxy groups in the 26DHBA anion in both salts are involved in two intramolecular O—H...O hydrogen bonds. C—H...O and π–π interactions further stabilize the crystal structures of both compounds. Steady-state UV–Vis spectroscopy showed changes in the water solubility of xanthines after ionizable complex formation. The obtained salts I and II were also characterized by theoretical calculations, Fourier-transform IR spectroscopy (FT–IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and elemental analysis.


Chemosensors ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 295
Author(s):  
Didier Fasquelle ◽  
Nathalie Verbrugghe ◽  
Stéphanie Députier

Tungsten trioxide thin films were deposited on silicon substrates by non-reactive RF sputtering from a WO3 target at room temperature. The WO3 films were post-annealed at two different temperatures, 400 °C and 500 °C. The morphological and microstructural properties of these films were analyzed by using atomic force microscopy and X-ray diffraction. X-ray diffraction patterns only show WO3 oxide phases. The AFM images show different morphologies with smaller grains for the film annealed at 400 °C. WO3 sensing films and W heating elements were embedded in commercial cases for the fabrication of cost-effective gas sensors. The sensitivity and dynamic response of the sensors were analyzed under various concentrations of H2S, from 20 to 100 ppm, at SIMTRONICS SAS (3M Company, Saint Paul, MN, USA). A good sensitivity G/G0 of about 6.6 under H2S 100 ppm was obtained with the best sensor. An interesting dynamic response was observed in particular with a short response time. Additionally, the evolution of the sensitivity was studied, and a conduction model was proposed for explaining the conduction mechanism under H2S exposition.


Author(s):  
Marieta Muresan-Pop ◽  
Sergiu Macavei ◽  
Alexandru Turza ◽  
Gheorghe Borodi

Four new solvates of the anti-HIV compound etravirine [systematic name: 4-({6-amino-5-bromo-2-[(4-cyanophenyl)amino]pyrimidin-4-yl}oxy)-3,5-dimethylbenzonitrile, C20H15BrN6O] with dimethyl sulfoxide (C2H6OS, two distinct monosolvates), 1,4-dioxane (C4H8O2, the 0.75-solvate) and N,N-dimethylacetamide (C4H9NO, the monosolvate), which exhibit conversion to the same anhydrous etravirine phase upon desolvation, and a stable etravirinium oxalate salt {6-amino-5-bromo-4-(4-cyano-2,6-dimethylphenoxy)-2-[(4-cyanophenyl)amino]pyrimidin-1-ium hemioxalate, C20H16BrN6O+·0.5C2O4 2−} were obtained. The crystal structures were solved by single-crystal X-ray diffraction and analyzed by powder X-ray diffraction, and the intermolecular interactions were explored by Hirshfeld surface analysis. Lattice energies were evaluated using the atom–atom force field Coulomb–London–Pauli (AA CLP) approximation, which distributes the total energy as four separate contributions: Coulombic, polarization, dispersion and repulsion. The formation of the solvates and the oxalate salt was further characterized by thermal analysis and IR spectroscopy.


Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2765
Author(s):  
Gabriele Calabrese ◽  
Candida Pipitone ◽  
Diego Marini ◽  
Francesco Giannici ◽  
Antonino Martorana ◽  
...  

In this study, the structure and morphology, as well as time, ultraviolet radiation, and humidity stability of thin films based on newly developed 1D (PRSH)PbX3 (X = Br, I) pseudo-perovskite materials, containing 1D chains of face-sharing haloplumbate octahedra, are investigated. All films are strongly crystalline already at room temperature, and annealing does not promote further crystallization or film reorganization. The film microstructure is found to be strongly influenced by the anion type and, to a lesser extent, by the DMF/DMSO solvent volume ratio used during film deposition by spin-coating. Comparison of specular X-ray diffraction and complementary grazing incidence X-ray diffraction analysis indicates that the use of DMF/DMSO mixed solvents promotes the strengthening of a dominant 100 or 210 texturing, as compared the case of pure DMF, and that the haloplumbate chains always lie in a plane parallel to the substrate. Under specific DMF/DMSO solvent volume ratios, the prepared films are found to be highly stable in time (up to seven months under fluxing N2 and in the dark) and to highly moist conditions (up to 25 days at 78% relative humidity). Furthermore, for representative (PRSH)PbX3 films, resistance against ultraviolet exposure (λ = 380 nm) is investigated, showing complete stability after irradiation for up to 15 h at a power density of 600 mW/cm2. These results make such thin films interesting for highly stable perovskite-based (opto)electronic devices.


Author(s):  
Hong-Tao Zhang ◽  
Xiao-Long Wang

The design and synthesis of metal–organic frameworks (MOFs) have attracted much interest due to the aesthetics of their crystalline architectures and their potential applications as new functional materials. A new twofold interpenetrated three-dimensional (3D) MOF, namely, poly[[triaqua(μ4-(2R,2′R)-2,2′-{[1,4-phenylenebis(carbonyl)]bis(azanediyl)}dipropionato-κ7 O 1:O 1,O 1′:O 4:O 4,O 4′,O 4′′)(μ3-(2R,2′R)-2,2′-{[1,4-phenylenebis(carbonyl)]bis(azanediyl)}dipropionato-κ3 O 1:O 4:O 4)dicadmium(II)] dihydrate], {[Cd2(C14H14N2O6)2(H2O)3]·2H2O} n , (I), has been synthesized by the reaction of Cd(CH3COO)2·2H2O with the synthesized ligand (2R,2′R)-2,2′-{[1,4-phenylenebis(carbonyl)]bis(azanediyl)}dipropionic acid (H2 L). Single-crystal X-ray diffraction analysis reveals that the carboxylate groups from two crystallographically independent L 2− dianions link the cadmium cations into a one-dimensional helical secondary building unit (SBU). The resulting SBUs are extended into a 3D metal–organic framework via the terephthalamide moiety of the ligand as a spacer. In the crystal, two independent MOFs interpenetrate each other, thus producing a twofold interpenetrated 3D architecture, which shows an unprecedented 2-nodal (7,9)-connected net with the point (Schläfli) symbol (37·46·58)(38·411·516·6). MOF (I) was further characterized by elemental analysis, IR spectroscopy, powder X-ray diffraction and thermogravimetric analysis. The photoluminescence properties and UV–Vis absorption spectrum of (I) have also been investigated. The MOF exhibits enhanced fluorescence emission with a high photoluminescence quantum yield of 31.55% and a longer lifetime compared with free H2 L.


2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Javier Gil ◽  
José Angel Delgado-García-Menocal ◽  
Eugenio Velasco-Ortega ◽  
Begoña Bosch ◽  
Luis Delgado ◽  
...  

Abstract Background New tetragonal zirconia polycrystal dental implants stabilized with yttria (Y-TZP) have appeared in the implantology market in the form of single piece or two-piece zircona implant system. These new type of implants improve the aesthetical properties compared to conventional commercially pure (c.p.) titanium used for implants, although the long term mechanical behavior of these new implants is not yet well known. In orthopaedics, the application of zirconia as femoral balls presented an important controversial use due to the premature fracture once implanted. Y-TZP dental implants can be affected by hydrothermal degradation and its behavior should be analysed to avoid a premature fracture. The scientific question behind the study is to analyse if the degradation mechanism observed in orthopaedics applications of Y-TZP is similar to that of Y-TZP for dental applications. Materials and methods For this purpose, 30 original Y-TZP dental implants and 42 Y-TZP femoral balls fractured in vivo have been studied. Dental implants were submitted to an accelerated hydrothermal degradation to compare with the femoral balls fractured in vivo. Phase transformation as well as the mechanical behaviour of the degraded samples was studied by X ray diffraction and nanoindentation tests, respectively. Results Results have shown that the fracture mechanism of dental implants does not resemble the mechanism observed in orthopaedic samples, presenting a good long-term behaviour. Conclusion The results ensure the good performance of zirconia dental implants, because the degradation of the ceramic is very limited and does not affect the mechanical properties.


Sign in / Sign up

Export Citation Format

Share Document