Search results for "Pyridine"
showing 10 items of 2516 documents
Identity Double-Proton Transfer in (3Z)-3-Hydroxy-1,4-di(quinolin-2-yl)but-3-en-2-one
2003
Although there is a very fast (on the NMR timescale) double-proton transfer in (1Z,3Z)-3-hydroxy-4-quinolin-2-yl-1-quinolin-2(1H)-ylidenbut-3-en-2-one (the product of the condensation of ethyl oxalate with 2-lithiomethylquinoline), it is the only species present in chloroform solution. Comparison of the product of condensation of ethyl oxalate with 2-lithiomethyl derivatives of pyridine (recent studies) and quinoline (present studies) shows that benzoannulation considerably affects the tautomeric equilibrium. The observed changes are not only quantitative but also qualitative. Moreover, contrary to the proton transfer in the pyridine tautomers, this process is fast in the quinoline tautomer…
A Boron Dipyrromethene (BODIPY)-Based Cu(II) -Bipyridine Complex for Highly Selective NO Detection.
2015
[EN] A BODIPY-containing Cu-II-bipyridine complex for the simple selective fluorogenic detection of NO in air and in live cells is reported. The detection mechanism is based on NO-promoted Cu-II to Cu-I reduction, followed by demetallation of the complex, which results in the clearly enhanced emission of the boron dipyrromethene (BODIPY) unit.
Preparation and structural studies on dibutyltin(IV) complexes with pyridine mono- and dicarboxylic acids
2004
Abstract A number of organotin(IV) complexes with pyridine mono- and dicarboxylic acids (containing ligating –COOH group(s) and aromatic {N} atoms) were prepared in the solid state. The bonding sites of the ligands were determined by means of FT-IR spectroscopic measurements. It was found that in most cases the –COO− groups form bridges between two central {Sn} atoms, thereby leading to polymeric (oligomeric) complexes. On this basis, the experimental 119Sn Mossbauer spectroscopic data were treated with partial quadrupole splitting approximations. The calculations predicted the existence of complexes with octahedral (oh) and trigonal-bipyramidal (tbp) structures, but the formation of comple…
6-Amino-1-benzyl-4-(4-chloro-phen-yl)-3-(4-pyrid-yl)-1,4-dihydro-pyrano[2,3-c]pyrazole-5-carbonitrile.
2008
The crystal structure of the title compound, C25H18ClN5O, was determined in the course of our studies on the synthesis of 1,4-dihydropyrano[2,3-c]pyrazole as an inhibitor of the p38 mitogen-activated protein kinase (MAPK). The compound was prepared via a base-catalysed synthesis from 1-benzyl-3-(4-pyridyl)-1H-pyrazol-5(4H)-one with p-chloroaldehyde and malononitrile. The crystal data obtained were used to generate a three-dimensional pharmacophore model for in silico database screening. The phenyl ring is disordered over two positions, with site occupancy factors of 0.55 and 0.45. The dihedral angles between the 1,4-dihydropyrano[2,3-c]pyrazole unit and the chlorophenyl and pyridine rings a…
2-(Mesitylmethylsulfanyl)pyridine N-oxide monohydrate
2008
In the title compound, C15H17NOS·H2O, the benzene and pyridine rings form a dihedral angle of 71.18 (2)°. The intramolecular S...O distance [2.737 (3) Å] is shorter than expected and, in terms of hybridization principles, the N—C—S angle [114.1 (2)°] is smaller than expected. The crystal structure is stabilized by intermolecular O—H...O and weak C—H...O hydrogen bonds. In addition, weak π–π stacking interactions with a centroid–centroid distance of 3.778 (3) Å are also observed.
Synthesis, structure and magnetic properties of iron (II), cobalt (II) and nickel (II) complexes of 2,6-bis(pyrazol-3-yl)pyridine and paramagnetic co…
2003
Abstract Iron (II), cobalt (II) and nickel (II) complexes of 2,6-bis(pyrazol-3-yl)pyridine (bpp) with [Cr(C2O4)3]3− have been prepared. They were characterised by single-crystal X-ray diffraction, magnetic susceptibility measurements and thermal gravimetric analyses. All three compounds are isostructural and they are formed by isolated [MII(bpp)2]2+ and [Cr(C2O4)3]3− complexes and free ClO4 −. As expected, only the salt [Fe(bpp)2]2[Cr(C2O4)3]ClO4·5H2O shows a thermal spin transition with transition temperature (T1/2) around 375 K that is correlated to the loss of water molecules.
Structural, magnetic and calorimetric studies of a crystalline phase of the spin crossover compound [Fe(tzpy)2(NCSe)2]
2013
The compound [Fe(tzpy)2(NCSe)2] (tzpy = 3-(2-pyridyl)-[1,2,3]triazolo[1,5-a]pyridine)) has been synthesized and its crystal structure, magnetic behavior and calorimetric properties investigated. Samples constituted of single crystals of [Fe(tzpy)2(NCSe) 2] display a relatively cooperative spin-state change centered at T1/2 ¿ 251.7 K with a hysteresis loop 3.5 K wide. The average enthalpy (¿H) and entropy (¿S) changes upon the spin crossover behavior (SCO) obtained from DSC measurements are 11.1 ± 0.4 kJ mol -1 and 44.5 ± 3 J K-1 mol-1, respectively. The magnetic and calorimetric data have been satisfactorily simulated using the mean-field regular solution model (Slichter-Drickamer) and the …
Imidazoporphyrins as supramolecular tectons: synthesis and self-assembly of zinc 2-(4-pyridyl)-1H-imidazo[4,5-b]porphyrinate
2019
International audience; 5,10,15,20-Tetramesityl-2-(4-pyridyl)-1H-imidazo[4,5-b]porphyrin (PyPor) bearing a pyridine donor site connected to the tetrapyrrolic macrocycle by a rigid imidazole linker was prepared in high yield by the condensation of the corresponding 2,3-dioxochlorin and 4-formylpyridine in the presence of ammonium acetate. After the insertion of a metal ion capable of metal–ligand axial coordination, namely Zn(II), this compound afforded self-complementary porphyrin PyPorZn which was suitable for self-assembly. In the crystals, this complex exists as a zigzag coordination polymer formed through the axial coordination of the pyridine nitrogen atom to the zinc ion of the neighb…
An Iron-Based Molecular Redox Switch as a Model for Iron Release from Enterobactin via the Salicylate Binding Mode
2001
The iron release mechanism from protonated ferric enterobactin [Fe(III)(enterobactinH(3))] via the salicylate binding mode was probed. For this purpose, a tripodal dodecadentate ligand incorporating three salicylamide (OO) and three bipyridine (NN) binding sites was synthesized as well as iron complexes thereof. It was shown that a ferric ion coordinates selectively to the hard salicylamides and a ferrous ion binds to the softer bipyridines. Upon reduction or oxidation, the iron translocates reversibly and intramolecularly from one site to the other, thus displaying switchlike properties. Both states were characterized by cyclic voltammetry and visible and Mössbauer spectroscopy. The Mössba…
Heterotrimetallic coordination polymers: {Cu(II)Ln(III)Fe(III)} chains and {Ni(II)Ln(III)Fe(III)} layers: synthesis, crystal structures, and magnetic…
2015
The use of the [Fe(III) (AA)(CN)4](-) complex anion as metalloligand towards the preformed [Cu(II) (valpn)Ln(III)](3+) or [Ni(II) (valpn)Ln(III) ](3+) heterometallic complex cations (AA=2,2'-bipyridine (bipy) and 1,10-phenathroline (phen); H2 valpn=1,3-propanediyl-bis(2-iminomethylene-6-methoxyphenol)) allowed the preparation of two families of heterotrimetallic complexes: three isostructural 1D coordination polymers of general formula {[Cu(II) (valpn)Ln(III) (H2O)3 (μ-NC)2 Fe(III) (phen)(CN)2 {(μ-NC)Fe(III) (phen)(CN)3}]NO3 ⋅7 H2O}n (Ln=Gd (1), Tb (2), and Dy (3)) and the trinuclear complex [Cu(II) (valpn)La(III) (OH2 )3 (O2 NO)(μ-NC)Fe(III) (phen)(CN)3 ]⋅NO3 ⋅H2O⋅CH3 CN (4) were obtained …