Polymorphism in 1-methylhydantoin: investigation by periodic DFT calculations and characterization of the third polymorph

CrystEngComm ◽  
2020 ◽  
Vol 22 (38) ◽  
pp. 6347-6359
Author(s):  
Bernardo A. Nogueira ◽  
Alberto Milani ◽  
Gulce O. Ildiz ◽  
José A. Paixão ◽  
Chiara Castiglioni ◽  
...  
Keyword(s):  
Dft Calculations ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Third ◽  
Periodic Dft Calculations ◽  
Periodic Dft

In previous studies, two different polymorphs of 1-methylhydantoin were identified (forms I and II) and characterized using infrared and Raman spectroscopies, and X-ray diffraction. In this work, a new polymorph of the compound (III) is described.

scholarly journals Preparation of Zirconium Oxide Powder Using Zirconium Carboxylate Precursors

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Mohammed H. Al-Hazmi ◽  
YongMan Choi ◽  
Allen W. Apblett
Keyword(s):  
Dft Calculations ◽  
Density Functional ◽  
Dissociative Adsorption ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
Experimental Findings ◽  
Periodic Dft Calculations ◽  
Good Agreement

Zirconia was prepared at low temperatures (<450°C) using single several source precursors based on zirconium carboxylates where the R groups were systematically varied. The combination of density functional theory (DFT) calculations and extensive characterization of the precursors (i.e., X-ray diffraction, thermal gravimetric analysis, infrared spectroscopy, and scanning electron microscopy) indicated that the carboxylic acid complexes may link the zirconium metal with a cis bidentate configuration. Periodic DFT calculations were performed to examine the interaction between monoclinic ZrO2 and propanoic acid. Dissociative adsorption takes place through the cis bidentate structure with an adsorption energy of −1.43 eV. Calculated vibrational frequencies using the optimized structure are in good agreement with experimental findings.

scholarly journals Kinetic Analysis of the Thermal Decomposition of a Synthetic Mercury Jarosite

Minerals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 200 ◽  
Author(s):  
Mizraim Flores ◽  
Iván Reyes ◽  
Elia Palacios ◽  
Francisco Patiño ◽  
Julio Juárez ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Thermal Decomposition ◽  
Environmental Concern ◽  
Frequency Factor ◽  
X Ray Diffraction ◽  
Thermal Decomposition Process ◽  
X Ray ◽  
The Third ◽  
Mercury Oxide

Jarosites are widely used in the hydrometallurgical industry of zinc to eliminate iron and other impurities contained in the concentrates. However, these compounds can also incorporate elements of significant environmental concern such as Tl+, Hg2+, Pb2+, Cd2+, Cr(VI), and As(V). In this work, the characterization of a synthetic mercury jarosite and its thermal decomposition kinetics are reported. XRD and FTIR analyses confirm that a mercury jarosite—Hg0.40(H3O)0.2]Fe2.71(SO4)2.17(OH)4.79(H2O)0.44—was successfully synthesized. Four mass loss events were observed by thermogravimetric analysis at 290 °C, 365 °C, 543 °C, and 665 °C. The third event corresponds to mercury decomposition into mercury oxide, whilst the forth is related to the jarosite to hematite transformation determined by X-ray diffraction starting at around 600 °C. According to the kinetic parameters (activation energy and frequency factor) of the thermal decomposition process, the fourth stage required the highest energy (Ea = 234.7 kJ∙mol−1), which corresponds to elimination of sulfur and oxygen from the jarosite lattice. Results show that jarosite-type compounds have the capability to incorporate heavy metals into their structure, retaining them even at high temperatures. Therefore, they can be used as a remediation strategy for heavy metals, such as mercury and others elements of environmental concern.

Characterization of molybdenum monomeric oxide species supported on hydroxylated silica: a DFT study

2014 ◽  
Vol 16 (34) ◽  
pp. 18253-18260 ◽  
Author(s):  
Hazar Guesmi ◽  
Robert Gryboś ◽  
Jarosław Handzlik ◽  
Frederik Tielens
Keyword(s):  
Dft Calculations ◽  
Amorphous Silica ◽  
Silica Surface ◽  
Dft Study ◽  
Periodic Dft Calculations ◽  
Periodic Dft

Periodic DFT calculations have been performed on molybdenum(vi) oxide species supported on the hydroxylated amorphous silica surface.

SEM and XRD Characterization of Ni-Hf Alloys at Low Hf Concentration

2006 ◽  
Vol 518 ◽  
pp. 325-330 ◽  
Author(s):  
Ana Umićević ◽  
H.E. Mahnke ◽  
Bozidar Cekić ◽  
Jasna Grbović Novaković ◽  
V. Koteski ◽  
...  
Keyword(s):  
Local Structure ◽  
X Ray Diffraction ◽  
Characterization Methods ◽  
X Ray ◽  
Additional Information ◽  
The Third ◽  
Two Phases ◽  
X Ray Absorption ◽  
Fcc Structure

The alloying and phase formation in Ni-Hf samples with 0.2-, 2-, and 5-at.% Hf were studied by X-ray diffraction (XRD) technique and scanning electron microscopy (SEM). Both characterization methods, XRD and SEM, reveal the presence of the HfNi5 phase (fcc structure) where the excess Ni atoms are present in the form of Ni or Ni-rich segregations in the sample containing 5-at.% Hf. The sample with 2-at.% Hf is characterized by the presence of the two phases present in the 5-at.% sample and by Hf atoms, which occupy substitutional lattice positions in the Ni lattice. Finally, in the third sample with 0.2-at.% Hf, the Hf atoms mainly substitute the Ni atoms in the lattice. This analysis is being complemented with additional information on the local structure around Hf by extended X-ray absorption fine structure spectroscopy (EXAFS).

scholarly journals Intramolecular sp2-sp3 Disequalization of Chemically Identical Sulfonamide Nitrogen Atoms: Single Crystal X-Ray Diffraction Characterization, Hirshfeld Surface Analysis and DFT Calculations of N-Substituted Hexahydro-1,3,5-Triazines

Crystals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 369 ◽  
Author(s):  
Alexey V. Kletskov ◽  
Diego M. Gil ◽  
Antonio Frontera ◽  
Vladimir P. Zaytsev ◽  
Natalia L. Merkulova ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Single Crystal ◽  
Surface Analysis ◽  
Noncovalent Interactions ◽  
Xrd Analysis ◽  
Hirshfeld Surface ◽  
Hirshfeld Surface Analysis ◽  
X Ray Diffraction ◽  
X Ray

In this manuscript, the synthesis and single crystal X-ray diffraction characterization of four N-substituted 1,3,5-triazinanes are reported along with a detailed analysis of the noncovalent interactions observed in the solid state architecture to these compounds, focusing on C–H···π and C–H···O H-bonding interactions. These noncovalent contacts have been characterized energetically by using DFT calculations and also by Hirshfeld surface analysis. In addition, the supramolecular assemblies have been characterized using the quantum theory of “atoms-in-molecules” (QTAIM) and molecular electrostatic potential (MEP) calculations. The XRD analysis revealed a never before observed feature of the crystalline structure of some molecules: symmetrically substituted 1,3,5-triazacyclohexanes possess two chemically identical sulfonamide nitrogen atoms in different sp2 and sp3-hybridizations.

Synthesis and Characterization of Hybrid Dimeric Steroid Spiroketals

Synthesis ◽  
2021 ◽  
Author(s):  
Martha C. Mayorquín-Torres ◽  
Mauricio Maldonado-Domínguez ◽  
MARCOS FLORES-ALAMOS ◽  
Martín A. Iglesias-Arteaga
Keyword(s):  
Dft Calculations ◽  
Structural Characterization ◽  
2D Nmr ◽  
Synthesis And Characterization ◽  
Sonogashira Coupling ◽  
X Ray Diffraction ◽  
X Ray ◽  
Synthetic Procedure ◽  
Nmr Techniques

The synthesis of six dimeric spiroketals bearing an estradiol half fused to the 5-or 5-epimers of androstane, cholestane and spirostane nuclei is described. The synthetic procedure comprises the Sonogashira coupling of different steroid alkynes with 2-iodoestradiol 17-monoacetate, followed by Pd-catalyzed spiroketalization. The structural characterization of the obtained hybrid dimers was performed using a combination of 1D and 2D NMR techniques, and was assisted by DFT calculations. Single crystal X-ray diffraction of one of the obtained compounds confirmed the proposed structures.

scholarly journals Determination of a complex crystal structure in the absence of single crystals: analysis of powder X-ray diffraction data, guided by solid-state NMR and periodic DFT calculations, reveals a new 2′-deoxyguanosine structural motif

2017 ◽  
Vol 8 (5) ◽  
pp. 3971-3979 ◽  
Author(s):  
Colan E. Hughes ◽  
G. N. Manjunatha Reddy ◽  
Stefano Masiero ◽  
Steven P. Brown ◽  
P. Andrew Williams ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid State Nmr ◽  
Structural Motif ◽  
X Ray Diffraction ◽  
X Ray ◽  
Complex Crystal Structure ◽  
Complex Crystal ◽  
Periodic Dft Calculations ◽  
Periodic Dft

A multi-technique strategy reveals a new hydrogen-bonding motif for a 2′-deoxyguanosine derivative.

Sign in / Sign up

Export Citation Format

Share Document