scholarly journals Micro-flow synthesis and structural analysis of sterically crowded diimine ligands with five aryl rings

2013 ◽  
Vol 9 ◽  
pp. 2336-2343 ◽  
Author(s):  
Shinichiro Fuse ◽  
Nobutake Tanabe ◽  
Akio Tannna ◽  
Yohei Konishi ◽  
Takashi Takahashi
Keyword(s):  
Structural Analysis ◽  
Nickel Complexes ◽  
Crystallographic Analysis ◽  
Detailed Structure ◽  
Flow Synthesis ◽  
X Ray ◽  
Diimine Ligands ◽  
One Step ◽  
Micro Flow ◽  
Polar Monomers

Sterically crowded diimine ligands with five aryl rings were prepared in one step in good yields using a micro-flow technique. X-ray crystallographic analysis revealed the detailed structure of the bulky ligands. The nickel complexes prepared from the ligands exerted high polymerization activity in the ethylene homopolymerization and copolymerization of ethylene with polar monomers.

Synthesis and Electrochemical Studies of Nickel β-Diketonate Complexes Incorporating Asymmetric Diimine Ligands

2010 ◽  
Vol 63 (1) ◽  
pp. 75 ◽  
Author(s):  
Phimphaka Harding ◽  
David J. Harding ◽  
Nitisastr Soponrat ◽  
Kittiya Tinpun ◽  
Sirirat Samuadnuan ◽  
...  
Keyword(s):  
Electrochemical Behaviour ◽  
Nickel Complexes ◽  
Electrochemical Studies ◽  
Peak Potential ◽  
Aryl Ring ◽  
X Ray ◽  
Coordination Modes ◽  
X Ray Crystallography ◽  
Diimine Ligands

The reaction of ppaX {(4-X-phenyl)-pyridin-2-ylmethylene-amine; X = H, Me, Et, OMe, F, Cl, Br, and I} with [Ni(β-diketonate)2(H2O)2] {β-diketonate = 1,3-diphenylpropanedionate (dbm), 2,2,6,6-tetramethyl-3,5-heptadionate (tmhd), or hexafluoroacetylacetonate (hfac)} yields a series of nickel complexes. X-ray crystallography reveals octahedral coordinated nickel centres with a cis arrangement of the β-diketonate ligands. The β-diketonate ligands adopt ‘planar’ or ‘bent’ coordination modes, whereas the aryl ring of the ppaX ligand is twisted with respect to the pyridylimine unit. The electrochemical behaviour of the complexes reveals quasi-reversible or irreversible one-electron oxidation to Ni(iii) in the case of the [Ni(tmhd)2(ppaX)] and [Ni(dbm)2(ppaX)] complexes, respectively. The peak potential for oxidation is dependent on the type of β-diketonate ligand but essentially independent of the substituent, X, on the ppaX ligand. The [Ni(β-diketonate)2(ppaX)] complexes (X = F, Cl, Br, and I) also undergo ligand based reduction.

scholarly journals Benzylaminoethyureido-Tailed Benzenesulfonamides: Design, Synthesis, Kinetic and X-ray Investigations on Human Carbonic Anhydrases

2020 ◽  
Vol 21 (7) ◽  
pp. 2560 ◽  
Author(s):  
Majid Ali ◽  
Murat Bozdag ◽  
Umar Farooq ◽  
Andrea Angeli ◽  
Fabrizio Carta ◽  
...  
Keyword(s):  
Carbonic Anhydrase ◽  
Design Strategy ◽  
Binding Mode ◽  
Crystallographic Analysis ◽  
Carbonic Anhydrases ◽  
Detailed Structure ◽  
Design Synthesis ◽  
X Ray ◽  
Structure Activity ◽  
New Compounds

A drug design strategy of carbonic anhydrase inhibitors (CAIs) belonging to sulfonamides incorporating ureidoethylaminobenzyl tails is presented. A variety of substitution patterns on the ring and the tails, located on para- or meta- positions with respect to the sulfonamide warheads were incorporated in the new compounds. Inhibition of human carbonic anhydrases (hCA) isoforms I, II, IX and XII, involving various pathologies, was assessed with the new compounds. Selective inhibitory profile towards hCA II was observed, the most active compounds being low nM inhibitors (KIs of 2.8–9.2 nM, respectively). Extensive X-ray crystallographic analysis of several sulfonamides in an adduct with hCA I allowed an in-depth understanding of their binding mode and to lay a detailed structure-activity relationship.

scholarly journals X-ray structure of an unusual glycoluril derivative conformation: Structural analysis and influencing factors

2020 ◽  
pp. 174751982096101
Author(s):  
Jungang Wang ◽  
Shanghui Yang ◽  
Qiling Zou ◽  
Huanjiang Wang ◽  
Hongqing Li
Keyword(s):  
Hydrogen Bonding ◽  
Structural Analysis ◽  
Influencing Factors ◽  
Crystallographic Analysis ◽  
Solvation Effect ◽  
Conformational Behavior ◽  
Slow Evaporation ◽  
X Ray ◽  
Effect Of Solvent ◽  
Solvent Water

The synthesis and X-ray structure of a novel glycoluril derivative are described. The crystal of the glycoluril derivative is obtained by slow evaporation in a refrigerator at about 5 °C. X-ray crystallographic analysis revealed that the compound crystallized in an unusual as conformation instead of the usual clip-shaped aa conformation. Structural analysis shows that the solvation effect, hydrogen bonding, and space-occupying effect influenced the crystallization conformation of the derivative. The X-ray crystallographic analysis in this work provides additional crystallographic evidence of the as conformation of the 3U glycoluril derivative and shows the effect of solvent water on the conformational behavior.

Far-red absorbing azodipyrrin dyes — Synthesis, X-ray crystallographic, and spectral characterization of 1,9-diazodipyrrins and their metal complexes

2011 ◽  
Vol 89 (4) ◽  
pp. 481-487 ◽  
Author(s):  
Yan Li ◽  
David Dolphin
Keyword(s):  
Metal Complexes ◽  
Zinc Complex ◽  
Nickel Complexes ◽  
Crystallographic Analysis ◽  
Zinc Complexes ◽  
Spectral Characterization ◽  
X Ray ◽  
Almost All ◽  
C Nmr

A series of novel 1,9-diazodipyrrins (4) were readily synthesized by reacting aryldiazonium salts with 5-aryldipyrromethanes under both acidic and basic conditions. The zinc complex of 1,9-diphenylazodipyrrin (5aZn) was confirmed by X-ray crystallographic analysis, and 1,9-diazodipyrrins and their zinc and nickel complexes (5M) were characterized by 1H and 13C NMR, IR, UV–vis, and MS. All of the metal complexes absorb almost all colours of the rainbow; the absorption maximums are >650 nm and the half-band widths are over 100 nm. The fluorescence of the zinc complexes of 1,9-diphenylazodipyrrin (5aZn) and 1,9-di(2-iodophenylazo)dipyrrin (5cZn) were also explored.

scholarly journals Synthesis and Crystal Structures of 4,5-Dihydroimidazo[1,5-b]pyrazol-6-ones

SynOpen ◽  
2020 ◽  
Vol 04 (04) ◽  
pp. 71-83
Author(s):  
Antonio Guirado ◽  
María Vera ◽  
Bruno Martiz ◽  
Francisco Ródenas ◽  
José A. Sandoval ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Hydrogen Chloride ◽  
Pyrazole Ring ◽  
Crystallographic Analysis ◽  
Ring System ◽  
X Ray ◽  
One Step ◽  
Chloride Elimination

AbstractThe synthesis of previously unattainable 2,5-disubstituted 4,5-dihydroimidazo[1,5-b]pyrazol-6-ones has been developed. Electrochemical reductions of readily available 2,2,2-trichloroethylideneacetophenones were followed by reaction with hydrazine, leading to 3-aryl-5-dichloromethyl-2-pyrazolines. These were treated with isocyanates to obtain the corresponding aminocarbonyl derivatives, which were found to be able to form an otherwise almost inaccessible imidazo[1,5-b]pyrazole ring system via a one-step reaction involving internal condensation followed by hydrogen chloride elimination and aromatization. The molecular­ structures of 2-(4-methylphenyl)-5-tosyl-4,5-dihydro­imidazo[1,5-b]pyrazol-6-one, 5-dichloromethyl-N-(4-chlorophenyl)-4,5-dihydro-3-p-tolylpyrazole-1-carboxamide, and 5-(4-bromophenyl)-2-p-tolyl-4,5-dihydroimidazo[1,5-b]pyrazol-6-one were determined by X-ray crystallographic analysis.

Quaternary structure of Limulus polyphemus hemocyanin

1978 ◽  
Vol 36 (2) ◽  
pp. 176-177
Author(s):  
T. Wichertjes ◽  
E.J. Kwak ◽  
E.F.J. Van Bruggen
Keyword(s):  
Electron Microscopy ◽  
Functional Properties ◽  
Horseshoe Crab ◽  
Temperature Jump ◽  
Quaternary Structure ◽  
Crystallographic Analysis ◽  
Limulus Polyphemus ◽  
Oxygen Binding ◽  
X Ray ◽  
Intact Molecule

Hemocyanin of the horseshoe crab (Limulus polyphemus) has been studied in nany ways. Recently the structure, dissociation and reassembly was studied using electron microscopy of negatively stained specimens as the method of investigation. Crystallization of the protein proved to be possible and X-ray crystallographic analysis was started. Also fluorescence properties of the hemocyanin after dialysis against Tris-glycine buffer + 0.01 M EDTA pH 8.9 (so called “stripped” hemocyanin) and its fractions II and V were studied, as well as functional properties of the fractions by NMR. Finally the temperature-jump method was used for assaying the oxygen binding of the dissociating molecule and of preparations of isolated subunits. Nevertheless very little is known about the structure of the intact molecule. Schutter et al. suggested that the molecule possibly consists of two halves, combined in a staggered way, the halves themselves consisting of four subunits arranged in a square.

RNA polymerase: Preparation and structural analysis of helical polymers

1984 ◽  
Vol 42 ◽  
pp. 152-153
Author(s):  
E. Loren Buhle ◽  
Pamela Rew ◽  
Ueli Aebi
Keyword(s):  
Structural Analysis ◽  
Rna Polymerase ◽  
Molecular Level ◽  
X Ray Diffraction ◽  
Helical Polymers ◽  
X Ray ◽  
E Coli ◽  
The Past ◽  
Ordered Arrays ◽  
Low Ionic Strength

While DNA-dependent RNA polymerase represents one of the key enzymes involved in transcription and ultimately in gene expression in procaryotic and eucaryotic cells, little progress has been made towards elucidation of its 3-D structure at the molecular level over the past few years. This is mainly because to date no 3-D crystals suitable for X-ray diffraction analysis have been obtained with this rather large (MW ~500 kd) multi-subunit (α2ββ'ζ). As an alternative, we have been trying to form ordered arrays of RNA polymerase from E. coli suitable for structural analysis in the electron microscope combined with image processing. Here we report about helical polymers induced from holoenzyme (α2ββ'ζ) at low ionic strength with 5-7 mM MnCl2 (see Fig. 1a). The presence of the ζ-subunit (MW 86 kd) is required to form these polymers, since the core enzyme (α2ββ') does fail to assemble into such structures under these conditions.

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