scholarly journals Emodin Scavenging of Superoxide Radical Includes π–π Interaction. X-Ray Crystal Structure, Hydrodynamic Voltammetry and Theoretical Studies

Antioxidants ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 194 ◽  
Author(s):  
Miriam Rossi ◽  
Kelly Wen ◽  
Francesco Caruso ◽  
Stuart Belli
Keyword(s):  
Density Functional ◽  
Superoxide Radical ◽  
Therapeutic Option ◽  
Color Variation ◽  
Stable Complex ◽  
X Ray ◽  
X Ray Crystallography ◽  
Π Stacking ◽  
Vis Spectroscopy ◽  
Voltaic Cell

The naturally occurring anthraquinone emodin is found in many plants that have been part of traditional Chinese medicine (TCM) for thousands of years. Recent pharmacological studies suggest that emodin might be a valuable therapeutic option for the treatment of various diseases. We describe the antioxidant effects of emodin on the superoxide radical. Our techniques include X-ray crystallography, density functional theory (DFT), and a recently developed cyclovoltammetry improvement, the rotating ring-disk electrode (RRDE) method. X-ray results show offset π–π stacking of emodin units in the crystal, and this type of interaction is supported by the DFT, which indicates one superoxide interacting via π–π stacking with the quinone moiety, by transferring one electron to the ring, and inducing some quinone aromatization. The second superoxide seems to form a stable complex after interacting with the H(hydroxyl) in position 3 of emodin. We show that one molecule of emodin sequesters two molecules of superoxide: one forming a complex with H(hydroxyl) in position 3, and the other due to π–π oxidation of superoxide and emodin ring reduction. We conclude that emodin is a very strong antioxidant. Color variation in the voltaic cell was observed during the RRDE study. This was analyzed and explained using a mini-grid gold electrode for UV-Vis spectroscopy in the voltaic cell.

scholarly journals Steric Effects of Alkyl Substituents at N-Donor Bidentate Amines Direct the Nuclearity, Bonding and Bridging Modes in Thiocyanato-Copper(II) Complexes

2018 ◽  
Author(s):  
Franz A. Mautner ◽  
Roland C. Fischer ◽  
Ana Torvisco ◽  
Maher M. Henary ◽  
Andrew Milner ◽  
...  
Keyword(s):  
Density Functional ◽  
Steric Effects ◽  
Functional Theory ◽  
X Ray ◽  
X Ray Crystallography ◽  
Monomeric Complex ◽  
Vis Spectroscopy ◽  
Specific Geometry ◽  
Bonding And Bridging

A series of Cu(II)-thiocyanato complexes derived from sterically hindered N-donors diamines were synthesized and characterized: catena-[Cu(Me3en)(μ-NCS)(NCS)] (1), catena-[Cu(NEt2Meen)(μ-NCS)(NCS)] (2), catena-[Cu(N,N,2,2-Me4pn)(μ-NCS)(NCS)] (3), the dimeric: [Cu2(N,N′-isp2en)2(μ-NCS)2(NCS)2] (4) and the monomeric complex [Cu(N,N′-t-Bu2en)(NCS)2] (5), where Me3en = N,N,N′-Trimethylethylenediamine, NEt2Meen = N,N-diethyl-N′-methylethylenediamine, N,N,2,2-Me4pn = N,N,2,2-tetramethylpropylenediamine, N,N′-isp2en = N,N′-diisopropylethylenediamine and N,N′-t-Bu2en = N,N′-di(tert-butyl)ethylenediamine. The complexes were characterized by elemental microanalyse, IR and UV-Vis spectroscopy and single crystal X-ray crystallography. Density Functional Theory was used to evaluate the role of steric effects in compounds 4 and 5 and how this may affect the adaption of a specific geometry, NCS-bonding mode and the dimensionality of the resulting complex.

scholarly journals Steric Effects of Alkyl Substituents at N-Donor Bidentate Amines Direct the Nuclearity, Bonding and Bridging Modes in Isothiocyanato-Copper(II) Coordination Compounds

Crystals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 38 ◽  
Author(s):  
Franz Mautner ◽  
Roland Fischer ◽  
Ana Torvisco ◽  
Maher Henary ◽  
Andrew Milner ◽  
...  
Keyword(s):  
Coordination Compounds ◽  
Density Functional ◽  
Steric Effects ◽  
Functional Theory ◽  
X Ray ◽  
X Ray Crystallography ◽  
Vis Spectroscopy ◽  
Specific Geometry ◽  
Bonding And Bridging

A series of Cu(II)-isothiocyanato coordination compounds derived from sterically hindered N-donor diamines were synthesized and characterized: catena-[Cu(Me3en)(μ-NCS)(NCS)] (1), catena-[Cu(NEt2Meen)(μ-NCS)(NCS)] (2), catena-[Cu(N,N,2,2-Me4pn)(μ-NCS)(NCS)] (3), the dimeric: [Cu2(N,N′-isp2en)2(µ-NCS)2(NCS)2] (4) and the monomeric compound [Cu(N,N′-t-Bu2en)(NCS)2] (5), where Me3en = N,N,N′-trimethylethylenediamine, NEt2Meen = N,N-diethyl-N′-methylethylenediamine, N,N,2,2-Me4pn = N,N,2,2-tetramethylpropylenediamine, N,N′-isp2en = N,N′-diisopropylethylenediamine and N,N′-t-Bu2en = N,N′-di(tert-butyl)ethylenediamine. The coordination compounds were characterized by elemental microanalyses, IR, and UV–Vis spectroscopy as well as single crystal X-ray crystallography. Density Functional Theory (DFT) was used to evaluate the role of steric effects in compounds 4 and 5 and how this may affect the adaption of a specific geometry, NCS-bonding mode, and the dimensionality of the resulting coordination compound.

Highly Electron-Deficient Pyridinium-Nitrones for Rapid and Tunable Inverse-Electron-Demand Strain-Promoted Alkyne-Nitrone Cycloaddition to Bicyclo[6.1.0]nonyne

2019 ◽  
Author(s):  
Praveen Gunawardene ◽  
Wilson Luo ◽  
Alexander M. Polgar ◽  
John F. Corrigan ◽  
Mark Workentin
Keyword(s):  
Density Functional Theory ◽  
Reaction Kinetics ◽  
Density Functional ◽  
Functional Theory ◽  
X Ray ◽  
Inverse Electron Demand ◽  
X Ray Crystallography ◽  
Electron Demand

<div> <div> <p>Highly accelerated inverse-electron-demand strain-promoted alkyne-nitrone cycloaddition (IED SPANC) between a sta- ble cyclooctyne (bicyclo[6.1.0]nonyne (BCN)) and nitrones delocalized into a Cα-pyridinium functionality is reported, with the most electron-deficient “pyridinium-nitrone” displaying among the most rapid cycloadditions to BCN that is currently reported. Density functional theory (DFT) and X-ray crystallography are explored to rationalize the effects of N- and Cα-substituent modifications at the nitrone on IED SPANC reaction kinetics and the overall rapid reactivity of pyridinium-delocalized nitrones.</p> </div> </div>

Synthesis and characterization of a linked, π-π stacked organotin compound of 2-mercapto-6-nitrobenzothiazolyl diphenyltin chloride with 2-ethoxyl-6-nitrobenzothiazole

2003 ◽  
Vol 81 (7) ◽  
pp. 825-831 ◽  
Author(s):  
Chunlin Ma ◽  
Qin Jiang ◽  
Rufen Zhang
Keyword(s):  
Title Compound ◽  
Organotin Compound ◽  
X Ray Diffraction ◽  
X Ray ◽  
Stacking Interaction ◽  
X Ray Crystallography ◽  
H Nmr ◽  
Π Stacking ◽  
Π Stacking Interaction ◽  
Molecular Components

The new organotin compound, Ph2Sn(Cl)[S(C7H3N2O2S)]·[(C7H3N2O2S)OEt], assembled by an intermolecular aromatic benzothiazole–benzothiazole π-π stacking interaction, has been synthesized by the reaction of diphenyltin dichloride with 2-mercapto-6-nitrobenzothiazole. The title compound was characterized by elemental, IR, 1H NMR, and X-ray crystallography analyses. Single-crystal X-ray diffraction data reveals that the title compound has two different molecular components. The component Ph2Sn(Cl)[S(C7H3N2O2S)] has a pentacoordinate tin, which further forms an infinite one-dimensional chain by intermolecular non-bonded Cl···S interactions, resulting in an intercalation lattice that holds (C7H3N2O2S)OEt molecules. The formation of the molecule (C7H3N2O2S)OEt as well as its intercalated mechanism has also been discussed.Key words: organotin, assemble, π-π stacking interaction, 2-mercapto-6-nitrobenzothiazole, non-bonded interaction, crystal structure.

How big is big? Separation by conventional methods, X-ray and electronic structures of positional isomers of bis-tert-butylisocyano adduct of 2(3),9(10),16(17),23(24)-tetrachloro-3(2),10(9),17(16),24(23)-tetra(2,6-di-iso-propylphenoxy)-phthalocyaninato iron(II) complex

2016 ◽  
Vol 20 (01n04) ◽  
pp. 337-351 ◽  
Author(s):  
Derrick R. Anderson ◽  
Pavlo V. Solntsev ◽  
Hannah M. Rhoda ◽  
Victor N. Nemykin
Keyword(s):  
Electronic Structures ◽  
Density Functional ◽  
Positional Isomers ◽  
Excitation Energies ◽  
Functional Theory ◽  
X Ray ◽  
Vertical Excitation ◽  
X Ray Crystallography ◽  
Tddft Calculations ◽  
Insight Into

A presence of bulky 2,6-di-iso-propylphenoxy groups in bis-tert-butylisocyano adduct of 2(3),9(10),16(17),23(24)-tetrachloro-3(2),10(9),17(16),24(23)-tetra(2,6-di-iso-propylphenoxy)-phthalocyaninato iron(II) complex allows separation of two individual positional isomers and a mixture of the remaining two isomers using conventional chromatography. X-ray structures of “[Formula: see text]” and “[Formula: see text]” isomers were confimed by X-ray crystallography. Density functional theory (DFT) and time-dependent DFT (TDDFT) calculations of each individual positional isomer allowed insight into their electronic structures and vertical excitation energies, which were correlated with the experimental UV-vis and MCD spectra.

scholarly journals Synthesis of Chromium(II) Complexes with Chelating Bis(alkoxide) Ligand and Their Reactions with Organoazides and Diazoalkanes

Molecules ◽  
2020 ◽  
Vol 25 (2) ◽  
pp. 273 ◽  
Author(s):  
Sudheer S. Kurup ◽  
Richard J. Staples ◽  
Richard L. Lord ◽  
Stanislav Groysman
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Aryl Azides ◽  
Functional Theory ◽  
X Ray ◽  
X Ray Crystallography ◽  
Chromium Vi ◽  
Imido Complexes ◽  
Structure And Bonding

Synthesis of new chromium(II) complexes with chelating bis(alkoxide) ligand [OO]Ph (H2[OO]Ph = [1,1′:4′,1′’-terphenyl]-2,2′’-diylbis(diphenylmethanol)) and their subsequent reactivity in the context of catalytic production of carbodiimides from azides and isocyanides are described. Two different Cr(II) complexes are obtained, as a function of the crystallization solvent: mononuclear Cr[OO]Ph(THF)2 (in toluene/THF, THF = tetrahydrofuran) and dinuclear Cr2([OO]Ph)2 (in CH2Cl2/THF). The electronic structure and bonding in Cr[OO]Ph(THF)2 were probed by density functional theory calculations. Isolated Cr2([OO]Ph)2 undergoes facile reaction with 4-MeC6H4N3, 4-MeOC6H4N3, or 3,5-Me2C6H3N3 to yield diamagnetic Cr(VI) bis(imido) complexes; a structure of Cr[OO]Ph(N(4-MeC6H4))2 was confirmed by X-ray crystallography. The reaction of Cr2([OO]Ph)2 with bulkier azides N3R (MesN3, AdN3) forms paramagnetic products, formulated as Cr[OO]Ph(NR). The attempted formation of a Cr–alkylidene complex (using N2CPh2) instead forms chromium(VI) bis(diphenylmethylenehydrazido) complex Cr[OO]Ph(NNCPh2)2. Catalytic formation of carbodiimides was investigated for the azide/isocyanide mixtures containing various aryl azides and isocyanides. The formation of carbodiimides was found to depend on the nature of organoazide: whereas bulky mesitylazide led to the formation of carbodiimides with all isocyanides, no carbodiimide formation was observed for 3,5-dimethylphenylazide or 4-methylphenylazide. Treatment of Cr2([OO]Ph)2 or H2[OO]Ph with NO+ leads to the formation of [1,2-b]-dihydroindenofluorene, likely obtained via carbocation-mediated cyclization of the ligand.

Twisted Push - Pull Ethylenes

2008 ◽  
Vol 61 (10) ◽  
pp. 805 ◽  
Author(s):  
Rakesh Naduvile Veedu ◽  
Paul V. Bernhardt ◽  
Rainer Koch ◽  
Curt Wentrup
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Room Temperature ◽  
Dihedral Angles ◽  
Functional Theory ◽  
Activation Barriers ◽  
Rapid Rotation ◽  
X Ray ◽  
X Ray Crystallography ◽  
Calculated Activation

As determined by X-ray crystallography, Meldrum’s acid derivatives 5, 6, and 8 feature dihedral angles around the central C5=C7 double bond of 14–35°, whereas for the anion 9 this angle is 90°. Density functional theory and MP2 calculations are in agreement with the experimental X-ray data for compounds 5–8, but for anion 9 an angle of only ~65° is predicted. It is concluded that a part of the torsion is due to packing forces in the crystal. It is further concluded that these molecules undergo rapid rotation about the central CC bonds at room temperature (calculated activation barriers 5–14 kcal mol–1).

scholarly journals Synthesis, X-Ray Crystallography, Thermal Analysis, and DFT Studies of Ni(II) Complex with 1-Vinylimidazole Ligand

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Fatih Şen ◽  
Ramazan Şahin ◽  
Muharrem Dinçer ◽  
Ömer Andaç ◽  
Murat Taş
Keyword(s):  
Density Functional ◽  
Computational Study ◽  
Basis Sets ◽  
Mulliken Charge ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Dft Methods ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Density Functional Theory

The paper presents a combined experimental and computational study of hexa(1-vinylimidazole)Ni(II) perchlorate complex. The complex was prepared in the laboratory and crystallized in the monoclinic space group P21/n with a=8.442(5), b=13.686(8), c=16.041(9) Å, α=γ=90, β=96.638(5), and Z=1. The complex has been characterized structurally (by single-crystal X-Ray diffraction) and its molecular structure in the ground state has been calculated using the density functional theory (DFT) methods with 6-31G(d) and LanL2DZ basis sets. Thermal behaviour and stability of the complex were studied by TGA/DTA analyses. Besides, the nonlinear optical effects (NLO), molecular electrostatic potential (MEP), frontier molecular orbitals (FMO), and the Mulliken charge distribution were investigated theoretically.

scholarly journals Six-fold C–H borylation of hexa-peri-hexabenzocoronene

2020 ◽  
Vol 16 ◽  
pp. 391-397 ◽  
Author(s):  
Mai Nagase ◽  
Kenta Kato ◽  
Akiko Yagi ◽  
Yasutomo Segawa ◽  
Kenichiro Itami
Keyword(s):  
Density Functional ◽  
Bathochromic Shift ◽  
Density Functional Theory Calculations ◽  
Absorption Bands ◽  
Functional Theory ◽  
X Ray ◽  
X Ray Crystallography ◽  
Polycyclic Aromatic ◽  
Direct Functionalization ◽  
Poorly Soluble

Hexa-peri-hexabenzocoronene (HBC) is known to be a poorly soluble polycyclic aromatic hydrocarbon for which direct functionalization methods have been very limited. Herein, the synthesis of hexaborylated HBC from unsubstituted HBC is described. Iridium-catalyzed six-fold C–H borylation of HBC was successfully achieved by screening solvents. The crystal structure of hexaborylated HBC was confirmed via X-ray crystallography. Optoelectronic properties of the thus-obtained hexaborylated HBC were analyzed with the support of density functional theory calculations. The spectra revealed a bathochromic shift of absorption bands compared with unsubstituted HBC under the effect of the σ-donation of boryl groups.

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