scholarly journals Electronic and molecular structure relations in diiron compounds mimicking the [FeFe]-hydrogenase active site studied by X-ray spectroscopy and quantum chemistry

2017 ◽  
Vol 46 (37) ◽  
pp. 12544-12557 ◽  
Author(s):  
Ramona Kositzki ◽  
Stefan Mebs ◽  
Nils Schuth ◽  
Nils Leidel ◽  
Lennart Schwartz ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Quantum Chemistry ◽  
Active Site ◽  
Structural Features ◽  
X Ray

X-ray spectroscopy and DFT on diiron complexes revealed correlations of spectroscopic, electronic, and structural features.

Recent insights into lytic polysaccharide monooxygenases (LPMOs)

2018 ◽  
Vol 46 (6) ◽  
pp. 1431-1447 ◽  
Author(s):  
Tobias Tandrup ◽  
Kristian E. H. Frandsen ◽  
Katja S. Johansen ◽  
Jean-Guy Berrin ◽  
Leila Lo Leggio
Keyword(s):  
Active Site ◽  
Room Temperature ◽  
Experimental Studies ◽  
Binding Mode ◽  
Structural Features ◽  
Oxygen Species ◽  
Animal Kingdom ◽  
X Ray ◽  
Lytic Polysaccharide Monooxygenases ◽  
Polysaccharide Monooxygenases

Lytic polysaccharide monooxygenases (LPMOs) are copper enzymes discovered within the last 10 years. By degrading recalcitrant substrates oxidatively, these enzymes are major contributors to the recycling of carbon in nature and are being used in the biorefinery industry. Recently, two new families of LPMOs have been defined and structurally characterized, AA14 and AA15, sharing many of previously found structural features. However, unlike most LPMOs to date, AA14 degrades xylan in the context of complex substrates, while AA15 is particularly interesting because they expand the presence of LPMOs from the predominantly microbial to the animal kingdom. The first two neutron crystallography structures have been determined, which, together with high-resolution room temperature X-ray structures, have putatively identified oxygen species at or near the active site of LPMOs. Many recent computational and experimental studies have also investigated the mechanism of action and substrate-binding mode of LPMOs. Perhaps, the most significant recent advance is the increasing structural and biochemical evidence, suggesting that LPMOs follow different mechanistic pathways with different substrates, co-substrates and reductants, by behaving as monooxygenases or peroxygenases with molecular oxygen or hydrogen peroxide as a co-substrate, respectively.

scholarly journals Molecular Structure, Luminescent and DFT Computational Studies of Two Novel Europium(III) β-diketonate Complexes

2017 ◽  
Author(s):  
Haifeng Shao ◽  
Yanjun Hou ◽  
Jinyuan Bai ◽  
Haijun Niu
Keyword(s):  
Molecular Structure ◽  
Spectral Analysis ◽  
Thermal Analyses ◽  
Structural Features ◽  
Donor Ligands ◽  
Computational Studies ◽  
Transfer Energy ◽  
X Ray ◽  
Structures And Properties ◽  
Calculation Results

In this paper, the synthesis of two novel luminescent Eu3+ ion complexes [Eu(TFT)3(phen) (1) and Eu(TFT)3(bpy)•Hex (2)] based on the combination of 2-(2,2,2-trifluoroethyl)-1-tetralone (TFT), containing n-donor ligands (1,10-phenanthroline or 2,2'-Bipyridine) and Eu3+ ion is reported herein, and their structural features are discussed on the basis of X-ray crystallographic and thermal analyses. We observed that the ligands transfer energy effectively to the metal center by fluorescence, IR and UV spectrograms studies. The structures and properties of complexes 1-2 were optimized by the DFT theoretical calculation, and the calculation results were consistent with the experimental X-ray structure data and spectral analysis.

X-ray crystal and DFT study of a potent anti-HIV-1 agent: 2-(5,5-Dioxido-3-phenylpyrazolo[4,3-c][1,2]benzothiazin-4(2H)-yl)-N′-[(3-nitrophenyl)methylidene]acetohydrazide

2016 ◽  
Vol 15 (05) ◽  
pp. 1650038
Author(s):  
Muhammad Jawwad Saif ◽  
Matloob Ahmad ◽  
Nazeran Idrees
Keyword(s):  
Molecular Structure ◽  
Density Functional ◽  
Structural Features ◽  
Single Crystal Xrd ◽  
Functional Theory ◽  
X Ray ◽  
Derivative Formula ◽  
Homo And Lumo ◽  
Anti Hiv ◽  
Hiv 1

This study presents structural features of an important benzothiazine derivative -[Formula: see text]2-(5,5-Dioxido-3-phenylpyrazolo[4,3-c][1,2]benzothiazin-4(2H)-yl)-N[Formula: see text]-[(3-nitrophenyl)methylidene]acetohydrazide. Molecular structure is characterized by single crystal XRD and compared with optimized geometry at B3LYP/6-31G(d,p) and PBE0/6-31G(d,p) levels of density functional theory (DFT). Simulated properties (1H-NMR & IR) are in good correlation with experimental results. Electronic properties (coefficients of HOMO and LUMO) are also presented.

Ni-S(uper)O(xide)D(ismutase) Inspired Ni(II)-Amino Acid Complexes Covalently Grafted onto Merrifield’s Resin - Synthesis, Structure and Catalytic Activity

2012 ◽  
Vol 730-732 ◽  
pp. 1012-1017
Author(s):  
Zita Csendes ◽  
Janos T. Kiss ◽  
Bence Kutus ◽  
Pal Sipos ◽  
Istvan Pálinkó
Keyword(s):  
Superoxide Dismutase ◽  
Catalytic Activity ◽  
Amino Acid ◽  
Active Site ◽  
Structural Features ◽  
Test Reaction ◽  
Sod Activity ◽  
X Ray ◽  
Amino Acid Complexes ◽  
Scanning Electron

In this work the syntheses of covalently grafted Ni(II)-complexes formed with various N- or C-protected amino acid ligands (L-histidine, L-tyrosine, L-cysteine and L-cystine) inspired by the active site of the Ni-SOD enzyme are presented. Merrifield’s resin was used as support to mimic the proteomic skeleton of the enzyme. Conditions of the syntheses were altered and the structural features of the substances obtained were studied by infrared spectroscopy. It was found that the preparation of covalently anchored Ni(II)−amino acid complexes was successful in all cases. In many cases the structures of the anchored complexes and the coordinating groups substantially varied upon changing the conditions of the syntheses. The obtained materials were studied by energy dispersive X-ray fluorescence coupled to scanning electron microscope (SEM−EDX). All the covalently anchored materials displayed superoxide dismutase (SOD) activity and some proved to be exceptionally efficient in the biochemical test reaction.

scholarly journals The novel [Ni{(Ph2P)2N(CH2)3Si(OCH3)3-P,P´}I2] complex: Structural features and catalytic reactivity in the oligomerization of ethylene

2016 ◽  
Vol 14 (1) ◽  
pp. 351-356 ◽  
Author(s):  
Ioannis Stamatopoulos ◽  
Catherine P. Raptopoulou ◽  
Vassilis Psycharis ◽  
Panayotis Kyritsis
Keyword(s):  
Molecular Structure ◽  
Single Crystal ◽  
Structural Features ◽  
Spectroscopic Methods ◽  
The Novel ◽  
X Ray Diffraction ◽  
Homogeneous Catalysts ◽  
X Ray ◽  
Catalytic Reactivity ◽  
Complex Structural

AbstractThe novel [Ni{(Ph2P)2N(CH2)3Si(OCH3)3-P,P´}I2] complex (1) was synthesized and investigated by a variety of spectroscopic methods (IR, 1H and 31P NMR). The molecular structure of 1, determined by single crystal X-ray diffraction, was compared with those of the analogue [Ni{(Ph2P)2N(CH2)3Si(OCH3)3-P,P´}Cl2] complex (2) and the recently reported [Ni{iCPrP)2NH-P,P´}I2] complex. Complexes 1 and 2 were tested as homogeneous catalysts for the oligomerization of ethylene, leading to the formation of C4 and, to a smaller extent, C6 products, in moderate yields.

scholarly journals X-ray crystal structure of trans-bis(pyridin-3-yl)ethylene: comparing the supramolecular structural features among the symmetrical bis(n-pyridyl)ethylenes (n = 2, 3, or 4) constitutional isomers

2020 ◽  
Vol 76 (12) ◽  
pp. 1859-1862
Author(s):  
Jay Quentin ◽  
Eric W. Reinheimer ◽  
Leonard R. MacGillivray
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Single Crystal ◽  
Structural Features ◽  
The Other ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Packing Assembly

The molecular structure of trans-bis(pyridin-3-yl)ethylene (3,3′-bpe), C12H10N2, as determined by single-crystal X-ray diffraction is reported. The molecule self-assembles into two dimensional arrays by a combination of C—H...N hydrogen bonds and edge-to-face C—H...π interactions that stack in a herringbone arrangement perpendicular to the crystallographic c-axis. The supramolecular forces that direct the packing of 3,3′-bpe as well as its packing assembly within the crystal are also compared to those observed within the structures of the other symmetrical isomers trans-1,2-bis(n-pyridyl)ethylene ( n , n ′-bpe, where n = n′ = 2 or 4).

The crystal and molecular structure of tris(pentamethylenedithiocarbamate) chromium(III)-chloroform (1 : 2)

1981 ◽  
Vol 46 (1) ◽  
pp. 6-19 ◽  
Author(s):  
Viktor Kettman ◽  
Ján Garaj ◽  
Jaroslav Majer
Keyword(s):  
Molecular Structure ◽  
Structural Analysis ◽  
Crystal And Molecular Structure ◽  
Analysis Method ◽  
Complex Molecules ◽  
Coordination Polyhedra ◽  
X Ray ◽  
Cell Dimensions ◽  
Crustal Density ◽  
Unit Cell Dimensions

The crystal and molecular structure of [Cr(S2CN(CH2)5)3].2 CHCl3 was found by the X-ray structural analysis method. The value R 0.090 was found for 1 131 observed independent reflections. The substance crystallizes in a space group of symmetry P212121 with the following unit cell dimensions: a = 0.8675 (6), b = 1.815(2), c = 2.155(3) nm. The experimentally observed crustal density was 1.48 Mgm-3 and the value calculated for Z = 4 was 1.51 Mgm-3. The CrS6 coordination polyhedron has the shape of a trigonally distorted octahedron, where the D3 symmetry is a approximately retained. The degree of trigonal distortion expressed as the projection of the chelate S-Cr-S angle onto the plane perpendicular to the C3 pseudo axis is Φ = 41.7° (Φ = 60° for an octahedron). The skeleton of the structure formed by the complex molecules contains channels filled with chloroform molecules. The specific type of complex-chloroform interaction consists of the formation of hydrogen bonds of the chloroform protons with the fully occupied pπ-orbitals of the sulphur atoms in the coordination polyhedra. The low stability and crystal decomposition can be explained by loss of chloroform from the channels.

scholarly journals Molekül- und Kristallstruktur von 1.1-Dimethylsilylentitanocendichlorid, (CH3)2Si(C5H4)2TiCl2 / Molecular and Crystal Structure of l,r-Dimethylsilylene Titanocene Dichloride, (CH3)2Si(C5H4)2TiCl2

1981 ◽  
Vol 36 (10) ◽  
pp. 1208-1210 ◽  
Author(s):  
Hartmut Köpf ◽  
Joachim Pickardt
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Structure Determination ◽  
Titanocene Dichloride ◽  
Molecular And Crystal Structure ◽  
Monoclinic Space Group ◽  
Crystal Data ◽  
Space Group ◽  
X Ray ◽  
Structural Dimensions

Abstract The molecular structure of the bridged [1]-titanocenophane 1,1'-dimethylsilylene titanocene dichloride, (CH3)2Si(C5H4)2TiCl2, has been investigated by an X-ray structure determination. Crystal data: monoclinic, space group C2/c, Z = 4, a = 1332.9(3), 6 = 988.7(3), c = 1068.9(3) pm, β = 113.43(2)°. The results are compared with the structural dimensions of similar compounds: 1,1'-methylene titanocene dichloride, CH2(C5H4)TiCl2, with the unbridged titanocene dichloride, (C5H5)2TiCl2 and the ethylene-bridged compound (CH2)2(C5H4)2TiCl2

The X-Ray Molecular Structure of 1-(2′,4′-Dinitrophenyl)-1,2,3-triazole and the Problem of the Orthogonal Interaction Between a 'Pyridine-Like' Nitrogen and a Nitro Group

2005 ◽  
Vol 58 (11) ◽  
pp. 817 ◽  
Author(s):  
Glenn P. A. Yap ◽  
Fernando A. Jové ◽  
Rosa M. Claramunt ◽  
Dionisia Sanz ◽  
Ibon Alkorta ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Nitro Group ◽  
Title Compound ◽  
Theoretical Calculations ◽  
X Ray

The structure of the title compound serves for a discussion about the topic of orthogonal interactions. This interaction, although weak, is important due to its peculiar geometry. Other examples from the Cambridge Crystallographic Database, together with theoretical calculations are reported.

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