Search results for "Pyridine"
showing 10 items of 2516 documents
The preparation, IR spectrum and structure of the Di-μ3-hydroxo-μ-sulphatotetrakis-μ-(isonicotinato-N-oxide)tetraaqua-tetracopper(II)
1982
Abstract A very unusual new copper(II) complex with isonicotinate N-oxide (N-inicO), Cu4(N-inicO)4SO4(OH)2(H2O)4 has been prepared and its crystal and molecular structure determined from three dimensional X-ray diffraction data. The crystals belong to the monoclinic space group C2. The cell parameters are a = 19.089(8), b = 6.884(3), c = 19.533(12) A, β = 140.9(3)°, dobs = 1.99, dcalc = 2.01 and Z = 2. The structure was refined to a final R-value of 0.062. The monomeric tetranuclear complex resembles a space ship with the sulphate group at its top and pyridine rings as wings. Two copper atoms are very close to each other in the molecule; the Cu1Cu1′ distance is 2.885 A. The coordination ar…
1,2,4,5‐Benzenetetracarboxylic Acid and 4,4′‐Bipyridine as Ligands in Designing Low‐Dimensional Coordination Polymers
2004
The combined use of 1,2,4,5-benzenetetracarboxylic acid (H4bta) and 4,4′-bipyridine (bpy) as ligands with MnII and CoII ions afforded two polymeric compounds with the formulae [Mn(Hbta)(Hbpy)(H2O)2] (1) and [H2bpy][Co(bta)(bpy)(H2O)2] (2). 1 and 2 were prepared under hydrothermal conditions (145 °C, 3 h) and characterized by elemental analysis, IR spectroscopy, TG-DTA analysis and single-crystal X-ray diffraction methods. 1 exhibits a novel double chain structure growing along the b axis where the manganese atoms are linked by tris-monodentate Hbta3− ligands. The values of the manganese···manganese intrachain separations are 7.627(2) A [Mn(1)···Mn(1c); c = −x + 1/2, y − 1/2, −z] and 9.274(4…
Selective Formation of S4- and T-Symmetric Supramolecular Tetrahedral Cages and Helicates in Polar Media Assembled via Cooperative Action of Coordina…
2020
We report on the synthesis and self-assembly study of novel supramolecular monomers encompassing quadruple hydrogen-bonding motifs and metal-coordinating 2,2'-bipyridine units. When mixed with metal ions such as Fe2+ or Zn2+, the tetrahedron cage complexes are formed in quantitative yields and full diastereoselectivity, even in highly polar acetonitrile or methanol solvents. The symmetry of the complexes obtained has been shown to depend critically on the flexibility of the ligand. Restriction of the rotation of the hydrogen-bonding unit with respect to the metal-coordinating site results in a T-symmetric cage, whereas introducing flexibility either through a methylene linker or rotating be…
Dendritic Pyridine-Functionalized Polyesters and Their Polycationic Hydrogen Bonded Picrates: Synthesis and X-ray Structural Study of Weak Hydrogen …
2003
Nicotinato and isonicotinato functionalized pentaerythritol and dipentaerythritol dendritic polyester compounds were synthesized. The compounds were crystallized, and the single-crystal structures were determined. Protonation by picric acid produced charged dendritic polyesters. Analysis of the role of weak hydrogen bonding CH···π and π···π interactions in the solid state was performed and compared to the corresponding benzoxy analogues which were also synthesized. The tetranicotinate 3b and tetrabenzoate 4 were found to have analogous structures, which in turn differ from the structure of the tetraisonicotinate 3c. The difference is attributed to the crucial role of CH···O and CH···N hydro…
Synthesis and characterization of four novel manganese(II) chains formed by 4,4′-azobis(pyridine) and benzoate or nitrobenzoates: Stabilization of un…
2013
Abstract Four new manganese(II) coordination polymers: [Mn(4,4′-azpy)(C6H5COO)2](4,4′-azpy)0.5 (1), [Mn(4,4′-azpy)(p-(NO2)C6H4COO)2] (2), [Mn(4,4′-azpy)(m-(NO2)C6H4COO)2] (3) and [Mn(4,4′-azpy)(o-(NO2)C6H4COO)2(H2O)2] (4), where 4,4′-azpy = 4,4′-azobis(pyridine), have been synthesized by self-assembly of MnX2 (X = benzoate, p-, m-, or o-nitrobenzoates) together with 4,4′-azpy. All four complexes were characterized by elemental analyses, IR spectroscopy, thermal analyses, single-crystal X-ray diffraction analyses and variable-temperature magnetic measurements. The structural analyses reveal that complexes 1, 2 and 3 feature a 1D molecular ladder formed by syn–syn (complex 1) or syn–anti (com…
1,4-Dihydro-1-methyl-4-nitriminopyridine Dihydrate
1998
Molecules of the title compound, C6H7N302.2H20, are almost planar with the NNO2 nitrimino group twisted 8 (1) ° out of the plane of the pyridine ring. The nitrimino group and CsN ring form a conju- gated 7r-electron system. These molecules together with water molecules are arranged in planes, They are con- nected with each other by O--H.-.O, O--H...N and weaker C--H..-O hydrogen bonds. Four water mol- ecules form a planar square (OH..-O--H)2 ring with O-..O distances equal to 2.741 (2) and 2.778(2)A. These rings join pairs of molecular planes into double layers, interacting otherwise by van der Waals forces.
1,5-Dimethyl-2-nitrimino-1,2-dihydropyridine
2006
Methylation of 5-methyl-2-nitraminopyridine provides the title compound, C7H9N3O2, as the only product. The molecule consists of two planar fragments, viz. an aromatic ring and a nitrimino substituent. The NNO2 group is twisted by 17 (2)° out of the plane of the pyridine ring. Despite a small torsion angle between these fragments, the geometry of the molecule indicates the participation of the π-electrons in the C—N bond. The hydrogen bonds in the crystal structure seem to be too weak to generate any deformations observed in the molecule.
Host-Guest Complexes of C-Ethyl-2-methylresorcinarene and Aromatic N,N′-Dioxides
2017
The C‐ethyl‐2‐methylresorcinarene (1) forms 1:1 in‐cavity complexes with aromatic N,N′‐dioxides, only if each of the aromatic rings has an N−O group. The structurally different C‐shaped 2,2′‐bipyridine N,N′‐dioxide (2,2′‐BiPyNO) and the linear rod‐shaped 4,4′‐bipyridine N,N′‐dioxide (4,4′‐BiPyNO) both form 1:1 in‐cavity complexes with the host resorcinarene in C4v crown and C2v conformations, respectively. In the solid state, the host–guest interactions between the 1,3‐bis(4‐pyridyl)propane N,N′‐dioxide (BiPyPNO) and the host 1 stabilize the unfavorable anti‐gauche conformation. Contrary to the N,N′‐dioxide guests, the mono‐N‐oxide guest, 4‐phenylpyridine N‐oxide (4PhPyNO), does not form an…
Protection by beverages, fruits, vegetables, herbs, and flavonoids against genotoxicity of 2-acetylaminofluorene and 2-amino-1-methyl-6-phenylimidazo…
2002
Abstract Chinese hamster lung fibroblasts, genetically engineered for the expression of rat cytochrome P450 dependent monooxygenase 1A2 and rat sulfotransferase 1C1 (V79-rCYP1A2-rSULT1C1 cells), were utilized to check for possible protective effects of beverages of plant origin, fruits, vegetables, and spices against genotoxicity induced by 2-acetylaminofluorene (AAF) or 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). Antigenotoxic activities of juices from spinach and red beets against AAF could be monitored with similar effectivity by the HPRT-mutagenicity test (IC50=0.64%; 2.57%) and alkaline single cell gel electrophoresis (comet assay; IC50=0.12%; 0.89%) which detects DNA stran…
Enzyme-responsive silica mesoporous supports capped with azopyridinium salts for controlled delivery applications
2012
11 páginas, 7 figuras, 3 tablas y 2 esquemas