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Pyridyl

Distribution by Scientific Domains
Chemistry87%
Polymers and Materials Science9%
2 Other Domains4%
Distribution within Chemistry
Crystallography26%
Organic Chemistry13%
General & Introductory Chemistry10%

Terms modified by Pyridyl

  • pyridyl groups
  • pyridyl nitrogen atom
    		•
  • pyridyl ring
  • pyridyl substituent
    		•

    Selected Abstracts

    A Comparative Study of the Optical and Electroluminescent Properties of EuIII Complexes with TTA and 2-(2,-Pyridyl)azoles: The Crystal Structure of [Eu(TTA)3(PBO)]

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2006
    Li-Hua Gao
    Abstract Two EuIII mixed-ligand complexes, namely [Eu(TTA)3(PBO)]and [Eu(TTA)3(PBT)] [TTA = 1,1,1-trifluoro-3-(2-thenoyl)acetonato, PBO = 2-(2,-pyridyl)-1,3-benzoxazole, and PBT = 2-(2,-pyridyl)-1,3-benzothiazole], have been synthesized. [Eu(TTA)3(PBO)] has been structurally characterized by single-crystal X-ray diffraction analysis. The complex crystallizes in the monoclinic space group C2/c. The lattice parameters are a = 41.346(4), b = 10.0538(8), c = 20.3793(16) Å, , = 110.922(2)°, Z = 8. The EuIII ion is eight-coordinate, with three bidentate TTA, anions and one bidentate N,O-chelated PBO molecule. A comparative study by UV and emission spectroscopy was carried out and electroluminescent properties of the related complexes [Eu(TTA)3(PBO)] and [Eu(TTA)3(PBT)] are reported as well. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

    Exploiting Non-Innocent Ligands to Prepare Masked Palladium(0) Complexes,

    ANGEWANDTE CHEMIE, Issue 39 2010
    Dan A. Smith
    Ist er es oder ist er es nicht? Die Reaktion von [PdMe2(tmeda)] mit Pyridyl- N -di(tert -butyl)phosphanylimin liefert spontan einen ungewöhnlichen zweikernigen Palladium(I)-Komplex mit diradikalischem Liganden, der sich in Reaktionen mit neutralen Liganden und Chlorbenzol wie eine ,maskierte" Form von Pd0 verhält. [source]

    2-(3-Pyridyl)-1,3,8-tri­aza­naphthalene, a product of the catalytic transformation of 3-cyano­pyridine

    ACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2003
    Jan Janczak
    The title compound, C12H8N4, was obtained by thermal treatment of 3-cyano­pyridine in the presence of magnesium phthalocyanine as catalyst. The X-ray structure analysis, in direct contrast to molecular orbital calculations corresponding to the gas phase, shows the mol­ecule to be non-planar in the solid state, with an interplanar angle between the pyridine and 1,3,8-tri­aza­naphthalene rings of 13.33,(9)°. Mol­ecules related to one another by cell translation, and positioned at intervals consistent with ,,, intermolecular interactions, form stacks in the b direction. [source]

    ChemInform Abstract: Exceptionally Efficient Unsymmetrical Ruthenium(II) NNN Complex Catalysts Bearing a Pyridyl-Based Pyrazolyl,Imidazolyl Ligand for Transfer Hydrogenation of Ketones.

    CHEMINFORM, Issue 46 2008
    Fanlong Zeng
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    ChemInform Abstract: Spiroborate Esters in the Borane-Mediated Asymmetric Synthesis of Pyridyl and Related Heterocyclic Alcohols.

    CHEMINFORM, Issue 17 2008
    Viatcheslav Stepanenko
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    Synthesis and 1H NMR Structural Analysis of 11-Aryl/Heteroarylnaphtho[2,1-b]furans: X-Ray Crystal Structure of 11-(4,-Pyridyl)naphtho[2,1-b]furan.

    CHEMINFORM, Issue 47 2005
    Sabir H. Mashraqui
    Abstract For Abstract see ChemInform Abstract in Full Text. [source]

    4-(2-Pyridyl)piperazine-1-benzimidazoles as Potent TRPV1 Antagonists.

    CHEMINFORM, Issue 25 2005
    Bin Shao
    Abstract For Abstract see ChemInform Abstract in Full Text. [source]

    Hantzsch 1,4-dihydropyridines containing a nitrooxyalkyl ester moiety to study calcium channel antagonist structure,activity relationships and nitric oxide release

    DRUG DEVELOPMENT RESEARCH, Issue 4 2000
    Jeffrey-Tri Nguyen
    Abstract A group of 3-nitrooxyalkyl 5-alkyl 1,4-dihydro-2,6-dimethyl-4-(pyridyl)-3,5-pyridinedicarboxylates were prepared using a modified Hantzsch reaction that involved the condensation of a nitrooxyalkyl acetoacetate with an alkyl 3-aminocrotonate and a pyridinecarboxaldehyde. 1H NMR nuclear Overhauser enhancement (nOe) studies for 3-(3-nitrooxypropyl) 5-isopropyl 1,4-dihydro-2,6-dimethyl-4-(2-pyridyl)-3,5-pyridinedicarboxylate (17) indicates a predominant rotamer exists in solution where the pyridyl nitrogen atom is orientated above the 1,4-DHP ring system, and the pyridyl nitrogen atom is antiperiplanar to the 1,4-DHP ring H-4 proton. Variable temperature 1H NMR studies (,30 to +60°C) showed the 1,4-DHP NH proton in 17 is H-bonded in CHCl3 solution. This interaction is believed to be due to intermolecular H-bonding between the pyridyl nitrogen free electron pair and the 1,4-DHP NH proton. In vitro calcium channel antagonist (CCA) activities were determined using a muscarinic-receptor-mediated Ca+2 -dependent contraction of guinea pig ileal longitudinal smooth muscle assay. This class of compounds exhibited lower CCA activity (IC50 = 5.3 × 10,6 to 3.5 × 10,8 M range) than the reference drug nifedipine (IC50 = 1.4 × 10,8 M). For compounds having C-3 ,CH2CH2ONO2 and C-4 pyridyl substituents, the C-5 alkyl was a determinant of CCA (i -Pr > the approximately equipotent i -Bu, t -Bu, and Et analogs). The point of attachment of the isomeric C-4 pyridyl substituent was a determinant of CCA when C-3 ,CH2CH2ONO2 and C-5 i -Pr substituents were present providing the potency profile 2-pyridyl , 3-pyridyl > 4-pyridyl. CCA with respect to the C-3 nitrooxyalkyl substituent was inversely dependent on the length of the alkyl spacer. The percent nitric oxide (·NO) released in vitro by this group of compounds (range of 0.03,0.43%/ONO2 group), quantified as nitrite by reaction with the Griess reagent, was lower than that for the reference drug glycerol trinitrate (3.81%/ONO2 group). Nitric oxide release studies showed that the %·NO released was dependent on the number of ONO2 groups/molecule. A QSAR study for this group of compounds showed a correlation between the specific polarizability descriptor (SpPol) and %·NO release. Drug Dev. Res. 51:233,243, 2000. © 2001 Wiley-Liss, Inc. [source]

    1,3,5-Triazapentadiene Nickel(II) Complexes Derived from a Ketoxime-Mediated Single-Pot Transformation of Nitriles

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 16 2010
    Maximilian N. Kopylovich
    Abstract A series of cationic (2+) [Ni{HN=C(R)NHC(R)=NH}2](X)2 {R = 4-(Cl)C6H4 (1), 3-(NC)C6H4 (3), 4-(NC)C6H4 (4) and Me (7); X = Cl, (1, 3, 4) or MeCOO,·H2O (7)} and neutral [Ni{HN=C(R)NC(R)=NH}2](solvate) {R = 3-(Cl)-4-py (2), 3-py (5) and 4-py (6); solvate = MeOH and/or H2O; py = pyridyl} N,N -chelating bis(1,3,5-triazapentadiene/ato)nickel(II) [Ni(tap)2]2+/0 complexes has been easily generated by a ketoxime-mediated single-pot reaction of a nickel(II) salt [NiCl2·2H2O or Ni(MeCOO)2·4H2O] with 4-chlorobenzonitrile, isophthalonitrile, terephthalonitrile, acetonitrile, 2-chloro-4-cyanopyridine, 3-cyanopyridine or 4-cyanopyridine, respectively. The obtained compounds have been characterized by IR, 1H and 13C{1H} NMR spectroscopy, FAB-MS(+) or ESI-MS(+), elemental analyses and single-crystal X-ray diffraction [for 7 and solvated mono- {1a·(Me2CO)0.33·(MeOH)0.67} and bis-deprotonated (2b·2Me2CO, 4b·CHCl3, 5b·Me2CO and 6b·MeOH) products, formed upon recrystallization of 1, 2, 4, 5 and 6, respectively]. The crystal structures of all compounds bear similar monomeric Ni(tap)2 units with a nearly square-planar geometry. In addition, the structure of 7 features the formation of infinite 1D zig-zag water,acetate chains {[(H2O)2(MeCOO)2]2,}n, which multiply interact with the [Ni(tap)2]2+ cations to generate a 2D hydrogen-bonded supramolecular assembly. [source]

    Bis(terdentate) Pyrazole/Pyridine Ligands: Synthesis, Crystal Structures and Magnetic Properties of Bridged Binuclear and Tetranuclear Copper(II) Complexes

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 23 2009
    Akhilesh Kumar Singh
    Abstract A new binucleating bis(terdentate) ligand, 3,5-[3-bis(2-pyridyl)pyrazole-1-ylmethyl]pyrazole (HL2), was synthesized. Reaction of the deprotonated ligand L2 with hydrated CuII salts gives (,-pyrazolato)(,-hydroxido)-bridged binuclear and tetranuclear complexes [L2Cu2(,-OH)(ClO4)(MeCN)](ClO4) (2), [L2Cu2(dmf)2(,3 -OH)]2(ClO4)4·4dmf (3·4dmf) and [L2L,Cu2](ClO4)2 [4; HL, = 3-(2-pyridyl)pyrazole]. In these complexes, both ,-OH and ,3 -OH bridges were observed. This contrasts the situation for a dicopper(II) complex of the related bis(terdentate) ligand 3,5-bis[6(2,2,-dipyridyl)]pyrazole (HL1), {L1Cu2(OMe)(MeOH)[,1 - O -(NO3)]}{[Cu2(NO3)2(,-OMe)2]}0.5·MeOH (1·MeOH), where the shorter and more rigid ligand side arms enforce a larger Cu···Cu separation and the formation of a MeO,HOMe moiety within the bimetallic pocket. Molecular structures of all complexes were elucidated by X-ray crystallography. Variable-temperature magnetic susceptibility measurements (295,2 K) for powdered samples of complexes 2,4 reveal strong antiferromagnetic coupling between two copper centres. The magnitude of the coupling is discussed in view of the structural features. During the preparation of complex 4, partial ligand hydrolysis was also observed, but this strongly depends on the reaction conditions.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

    Spectroscopic and Computational Study on New Blue Emitting ReL(CO)3Cl Complexes Containing Pyridylimidazo[1,5- a]pyridine Ligands

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 23 2008
    Claudio Garino
    Abstract The structural and photophysical properties of three new ReL(CO)3Cl complexes (ReL1,ReL3) and their 1-(2-pyridyl)imidazo[1,5- a]pyridine ligands, namely 3-methyl-1-(2-pyridyl)imidazo[1,5- a]pyridine (L1), 1-(2-pyridyl)-3-[4-(trifluoromethyl)phenyl]imidazo[1,5- a]pyridine (L2), and 3-(4-nitrophenyl)-1-(2-pyridyl)imidazo[1,5- a]pyridine (L3), were studied by spectroscopy, X-ray diffraction, and computational methods. ReL1,ReL3 have high-energy singlet emissions arising from a , , ,* ligand-centered state. In oxygen-free acetonitrile solutions, the complexes display dual fluorescence due to intense ligand-centered triplet emission.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

    A New Donor-Stabilized Ditungsten Amido Alkoxido Species: Synthesis, Crystal Structure, Fluxionality, and Grafting onto Silica

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 35 2007
    Olivier Coutelier
    Abstract A new dimeric tungsten(III) complex containing amidoand chelating pyridine,alkoxido ligands was synthesized through protonolysis of [W2(NMe2)6] by 2-(2-pyridyl)propan-2-ol and fully characterized by X-ray diffraction and infrared and NMR spectroscopy. Intramolecular exchange processes were studied by variable-temperature NMR spectroscopy. The compound was grafted onto dehydroxylated silica by protonolysis of an amido,tungsten bond, and the structure of the supported species was investigated by infrared and solid-state (bidimensional) NMR spectroscopy. The reactivity of the molecular and grafted species toward alkynes was probed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

    [(Pyridylcarbonyl)pyridyl]triazolopyridines, Useful Ligands for the Construction of Polynuclear Coordination Compounds , Synthesis, Crystal Structure and Magnetic Properties of a Novel Tetranuclear Copper(II) Cubane,

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 29 2007
    Belén Abarca
    Abstract A new tetranuclear cubane Cu4O4 complex has been synthesised from assembly of CuII ions and the polydentate ligand (pyridin-2-yl){6-([1,2,3]triazolo[1,5- a]pyridin-3-yl)pyridin-2-yl}methanone. Crystallographic analysis indicates that the Cu4O4 unit has an S4 symmetry. The magnetic properties have been analysed using the H = ,2,i,jJijSiSj spin Hamiltonian. Two distinct coupling constants, 2J1,3 = ,37.4 cm,1 and 2J1,2 = ,2.6 cm,1, obtained from the fitting of the experimental data have been rationalised on the basis of a density functional study of magnetostructural correlations in cubane complexes containing the Cu4O4 core. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

    Efficient DNA Cleavage Induced by Copper(II) Complexes of Hydrolysis Derivatives of 2,4,6-Tri(2-pyridyl)-1,3,5-triazine in the Presence of Reducing Agents

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 6 2007
    Joaquín Borrás
    Abstract The reaction of 2,4,6-tri(pyridyl)-1,3,5-triazine (ptz) and copper(II) salts in dmf/water (1:1) results in the hydrolysis of ptz and formation of the anions bis(2-pyridylcarbonyl)amide (ptO2,) and bis(2-pyridylamine)amide (ptN2,), which are found in the complexes [Cu(ptN2)(OAc)]·3H2O (1), [Cu(ptO2)(OAc)(H2O)]·H2O (2), [Cu(ptN2)(for)]·3H2O (3) (for = formate), [Cu(ptO2)(for)(H2O)] (4), [Cu(ptO2)(benz)]·H2O (5) (benz = benzoate), and [Cu(ptO2)F(H2O)]2·3H2O (6). This report includes the chemical and spectroscopic characterization of all these complexes along with the crystal structures of 4,6. The coordination spheres of CuII in 4 and 5 are best described as distorted tetragonal square pyramidal for the former and distorted square planar for the latter. The crystal structure of 6 shows the presence of two discrete monomeric [Cu(ptO2)F(H2O)] entities in the crystallographic asymmetric unit in which both copper(II) ions have a distorted square-pyramidal coordination geometry. The binding of the complexes to DNA has been investigated with the aid of viscosity and thermal denaturation studies, both of which indicate that the interaction is probably due to the outer-sphere mechanism. The ability of the compounds to cleave DNA has also been tested. Efficient oxidative cleavage was observed in the presence of a mild reducing agent (ascorbate) and dioxygen. Mechanistic studies with reactive oxygen species (ROS) scavengers confirm that hydrogen peroxide, the hydroxyl radical, singlet oxygen-like species, and the superoxide anion are necessary diffusible intermediates in the scission process. A mechanism involving either the Fenton or theHaber,Weiss reaction plus the formation of copper oxene species is proposed for the DNA cleavage mediated by these compounds.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

    New Polar Pyrazolylborate Ligands and Their Basic Zinc Complex Chemistry

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 19 2006
    Cristina Pérez Olmo
    Abstract By refinement of Trofimenko's procedures, four new tris(pyrazolyl)borate (Tp) ligands bearing pyridyl and carboxamide substituents at the 3-positions of the pyrazole rings, were obtained. Two of them were identified by structure determinations of their potassium salts. Their coordinative properties were explored by preparing Tp*Zn-X complexes, with X = Cl, Br, I, NO3, OAc, phenolate, thiophenolate and diorganophosphate, including the cationic complexes [Tp*Zn·L]+ with L = methanol and pyrazole. From the spectra and structure determinations of these complexes it has become evident that the polar Tp* ligands favor coordination numbers higher than four for zinc, either by inducing bidentate coordination of the coligands X and L, using the carboxamide oxygen atoms for coordination, or by linking two Tp*Zn-X units through the pyridyl nitrogen atoms. As a result, the structural chemistry of these complexes is quite varied, and includes coordination dimers and polymers.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

    A Comparative Study of the Optical and Electroluminescent Properties of EuIII Complexes with TTA and 2-(2,-Pyridyl)azoles: The Crystal Structure of [Eu(TTA)3(PBO)]

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2006
    Li-Hua Gao
    Abstract Two EuIII mixed-ligand complexes, namely [Eu(TTA)3(PBO)]and [Eu(TTA)3(PBT)] [TTA = 1,1,1-trifluoro-3-(2-thenoyl)acetonato, PBO = 2-(2,-pyridyl)-1,3-benzoxazole, and PBT = 2-(2,-pyridyl)-1,3-benzothiazole], have been synthesized. [Eu(TTA)3(PBO)] has been structurally characterized by single-crystal X-ray diffraction analysis. The complex crystallizes in the monoclinic space group C2/c. The lattice parameters are a = 41.346(4), b = 10.0538(8), c = 20.3793(16) Å, , = 110.922(2)°, Z = 8. The EuIII ion is eight-coordinate, with three bidentate TTA, anions and one bidentate N,O-chelated PBO molecule. A comparative study by UV and emission spectroscopy was carried out and electroluminescent properties of the related complexes [Eu(TTA)3(PBO)] and [Eu(TTA)3(PBT)] are reported as well. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

    Template Synthesis, Crystal Structure and Luminescent Properties of Neutral N4O3 Tripodal LnIIIL Complexes (LnIII = La3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+ or Lu3+; H3L = Tris{[3,-(2,,-pyridyl)-5,- tert -butyl-2,-hydroxybenzylidene-2-imino]ethyl}amine)

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 4 2004
    Wai-Kwok Wong
    Abstract In the presence of Ln3+ (Ln = La, Eu, Gd, Tb, Dy, Ho, Er, Tm or Lu), tris(2-aminoethyl)amine condensed with three equivalents of 3-(2,-pyridyl)-5- tert -butyl-2-hydroxybenzaldehyde in methanol to give the neutral Schiff-base complex LnIIIL (Ln = La 1, Eu 2, Gd 3, Tb 4, Dy 5, Ho 6, Er 7, Tm 8 and Lu 9; H3L = tris{[3,-(2,,-pyridyl)-5,- tert -butyl-2,-hydroxybenzylidene-2-imino]ethyl}amine). The structures of compounds 4,7 were determined by X-ray crystallography. The crystal structure analyses revealed that the Schiff base behaves as a tri-deprotonated heptadentate ligand encapsulating the lanthanide metal ion within the N4O3 cavity, with all the pyridyl groups being pendant. Solution spectroscopic data suggest that the LnIIIL complexes remain intact in methanol and exist as nine-coordinate non-electrolytes with the lanthanide metal ions coordinated to the N4O3 cavity of the tripodal Schiff base and two solvent molecules. The solution photoluminescent properties of these lanthanide Schiff-base complexes were also examined. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

    Synthesis of "V-Shaped" syn -Bidentate Ligands Based on Mesitylene-Derived [1.1.1.1]Metacyclophane Blocked in a 1,3-Alternate Conformation

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 2 2003
    Cédric Klein
    Abstract A series of five new syn -bidentate ligands 14,18 based on the [1.1.1.1]metacyclophane backbone blocked in a 1,3-alternate conformation was achieved. The common building block for the preparation of ligands bearing two interaction sites located in a syn fashion (CN, SMe, p -pyridyl, p -methoxyphenyl and p -methylthiophenyl) is the dibromo derivative 12. All reported ligands were fully characterised by classical analytical methods and their 1,3-alternate conformation demonstrated. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

    Multifunctional Crosslinkable Iridium Complexes as Hole Transporting/Electron Blocking and Emitting Materials for Solution-Processed Multilayer Organic Light-Emitting Diodes

    ADVANCED FUNCTIONAL MATERIALS, Issue 7 2009
    Biwu Ma
    Abstract Here, a new series of crosslinkable heteroleptic iridium (III) complexes for use in solution processed phosphorescent organic light emitting diodes (OLEDs) is reported. These iridium compounds have the general formula of (PPZ-VB)2Ir(C,N), where PPZ-VB is phenylpyrazole (PPZ) vinyl benzyl (VB) ether; and the C,N ligands represent a family of four different cyclometallating ligands including 1-phenylpyrazolyl (PPZ) (1), 2-(4,6-difluorophenyl)pyridyl (DFPPY) (2), 2-(p-tolyl)pyridyl (TPY) (3), and 2-phenylquinolyl (PQ) (4). With the incorporation of two crosslinkable VB ether groups, these compounds can be fully crosslinked after heating at 180,°C for 30,min. The crosslinked films exhibit excellent solvent resistance and film smoothness which enables fabrication of high-performance multilayer OLEDs by sequential solution processing of multiple layers. Furthermore, the photophysical properties of these compounds can be easily controlled by simply changing the cyclometallating C,N ligand in order to tune the triplet energy within the range of 3.0,2.2,eV. This diversity makes these materials not only suitable for use in hole transporting and electron blocking but also as emissive layers of several colors. Therefore, these compounds are applied as effective materials for all-solution processed OLEDs with (PPZ-VB)2IrPPZ (1) acting as hole transporting and electron blocking layer and host material, as well as three other compounds, (PPZ-VB)2IrDFPPY (2), (PPZ-VB)2IrTPY(3), and (PPZ-VB)2IrPQ(4), used as crosslinkable phosphorescent emitters. [source]

    Rational Design of Chelating Phosphine Functionalized Os(II) Emitters and Fabrication of Orange Polymer Light-Emitting Diodes Using Solution Process,

    ADVANCED FUNCTIONAL MATERIALS, Issue 2 2008
    M. Cheng
    Abstract A new series of charge neutral Os(II) pyridyl azolate complexes with either bis(diphenylphosphino)methane (dppm) or cis -1,2-bis(diphenylphosphino)ethene (dppee) chelates were synthesized, and their structural, electrochemical, photophysical properties and thermodynamic relationship were established. For the dppm derivatives 3a and 4a, the pyridyl azolate chromophores adopt an eclipse orientation with both azolate segments aligned trans to each other, and with the pyridyl groups resided the sites that are opposite to the phosphorus atoms. In sharp contrast, the reactions with dppee ligand gave rise to the formation of two structural isomers for all three kind of azole chromophores, with both azolate or neutral heterocycles (i.e., pyridyl or isoquinolinyl fragments) located at the mutual trans -disposition around the Os metal (denoted as series of a and b complexes). These chelating phosphines Os(II) complexes show remarkably high thermal stability, among which and several exhibit nearly unitary phosphorescence yield in deaerated solution at RT. A polymer light-emitting device (PLED) prepared using 0.4 mol % of 5a as dopant in a blend of poly(vinylcarbazole) (PVK) and 30 wt % of 2- tert -butylphenyl-5-biphenyl-1,3,4-oxadiazole (PBD) exhibits yellow emission with brightness of 7208 cd m,2, an external quantum efficiency of 10.4 % and luminous efficiency of 36.1 cd A,1 at current density of 20 mA cm,2. Upon changing to 1.6 mol % of 6a, the result showed even better brightness of 9212 cd m,2, external quantum efficiency of 12.5 % and luminous efficiency of 46.1 cd A,1 at 20 mA cm,2, while the max. external quantum efficiency of both devices reaches as high as 11.7 % and 13.3 %, respectively. The high PL quantum efficiency, non-ionic nature, and short radiative lifetime are believed to be the determining factors for this unprecedented achievement. [source]

    Multiscale Approach of Photochromism: Synthesis and Photochromic Properties of a Diarylethene in Solution, in Nanoparticles, and in Bulk Crystals,

    ADVANCED MATERIALS, Issue 3 2009
    Arnaud Spangenberg
    A new photochromic diarylethene, 1,2-bis(5,-ethoxy-2,-(2,-pyridyl) thiazolyl) perfluorocyclopentene (1), is synthesized. Nanoparticles are obtained by laser ablation at both 355 and 532 nm, corresponding to the absorption wavelengths of the open and the closed forms. 1 can be reversibly photoswitched in various states: organic solution, bulk crystal, nanoparticle colloidal solution, and single nanoparticle, as demonstrated by dark-field scattering spectroscopy. [source]

    Gas-phase radical,radical recombination reactions of nitroxides with substituted phenyl radicals

    INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 4 2004
    J. L. Heidbrink
    Fourier-transform ion cyclotron resonance mass spectrometry has been used to examine gas-phase reactions of four different nitroxide free radicals with eight positively charged pyridyl and phenyl radicals (some containing a Cl, F, or CF3 substituent). All the radicals reacted rapidly (near collision rate) with nitroxides by radical,radical recombination. However, some of the radicals were also able to abstract a hydrogen atom from the nitroxide. The results establish that the efficiency (kreaction/kcollision) of hydrogen atom abstraction varies with the electrophilicity of the radical, and hence is attributable to polar effects (a lowering of the transition-state energy by an increase in its polar character). The efficiency of the recombination reaction is not sensitive to substituents, presumably due to a very low reaction barrier. Even so, after radical,radical recombination has occurred, the nitroxide adduct was found to fragment in different ways depending on the structure of the radical. For example, a cationic fragment was eliminated from the adducts of the more electrophilic radicals via oxygen anion abstraction by the radical (i.e., the nitroxide adduct cleaves heterolytically), whereas adducts of the less electrophilic radicals predominantly fragmented via homolytic cleavage (oxygen atom abstraction). Therefore, differences in the product branching ratios were found to be attributable to polar factors. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 216,229 2004 [source]

    Effect of water on zinc (II), cadmium (II) complexes with pyridylimidazole: Theoretical study of stability and electronic spectrum

    INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 2 2006
    Yi Liao
    Abstract The geometry structures of complexes such as [Zn(PIm)2(H2O)] and [Cd(PIm)2(H2O)2] [PIm = (2-(2,-pyridyl) imidazole)] are optimized by density functional theory (DFT) B3LYP methods. On the basis of their stable structures, the stability of the coordinated water existing in the complexes is analyzed quantitatively in terms of the interaction between the central metal and the coordinated water. The interaction energy of the Zn pyridylimidazole complex increased obviously by considering the intermolecular hydrogen bond (OH,N). The theoretical calculation well explained penta- and hexa-coordinated conformation, respectively, in Zn and Cd pyridylimidazole complexes. The spectral properties of the Zn Cd complexes have been studied by time-dependent density functional theory (TD-DFT). The calculation results show that the coordinated waters in Cd complexes have little effect on their spectral properties. While the axially coordinated waters in Zn pyridylimidazole cause a red shift in the absorption wavelength and change the pattern of charge transfer as a result of the effect of polarization from intermolecular hydrogen bond. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source]

    Structural motifs in ,-pyridyl- and ,-furylcinnamic acid assemblies, A molecular modeling study

    INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 2 2001
    I. Pálinkó
    Abstract The aggregation properties of stereoisomeric 2-(3,-furyl)-3-phenylpropenoic acids (FU3E, FU3Z, ,-furylcinnamic acids) and 2-(4,-pyridyl)-3-phenylpropenoic acids (PY4E, PY4Z, ,-pyridylcinnamic acids) were studied by the PM3 semiempirical quantum chemical method. Calculations revealed that (aromatic)CH,N(O) hydrogen bonds made possible the attachment of dimer units; thus, virtually infinite chains can be built out of FU3Z, PY4E, and PY4Z. The energy-minimized structure had zig-zag configuration. PY4Z dimers allowed the formation of ribbonlike network; however, the number of structural units could not be increased infinitely. One of the furyl derivatives (FU3E) could not be stabilized either in the ribbon or the chain form; however, (aromatic)CH,, or (aromatic),,(aromatic), interactions contribute to the packing pattern of the two dimers. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem 84: 269,275, 2001 [source]

    Preparation and pH-sensitivity of polyacrylonitrile (PAN) based porous hollow gel fibers

    JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008
    Xinyuan Shen
    Abstract Polyacrylonitrile based porous hollow gel fibers were prepared from PAN hollow fibers by oxidation and subsequent alkaline treatment. Fourier-transform infrared (FTIR), X-ray diffraction, and scanning electron microscope (SEM) analyses showed that the PAN porous hollow gel fiber was a kind of amphoteric fiber due to the combination of cationic groups of pyridyl and anionic groups of carboxyl; after gelation the hollow channel and finger-like pores on the fiber walls were conserved. The effects of cyclization reaction degree, alkaline solution concentration, and alkaline treatment time on the mechanical properties or pH-sensitive behavior of the porous hollow gel fibers were investigated. The elongation/contraction behavior was studied in detail. It was found that the gel fiber exhibited a large swelling in an alkaline solution and contracting in an acid solution; the swelling change in length was above 90%; the responsive time of elongation/contraction was less than 20 s; the maximum contraction force was 20 N/cm2; and pH-sensitivity was reversible. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

    Synthesis of tritium labelled CHS 828 and its prodrug EB 1627

    JOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 11 2005
    Søren Christian Schou
    Abstract The potent antitumoral cyanoguanidine CHS 828 and its prodrug EB 1627 have successfully been labelled with tritium. The pyridyl-3,5-dibromo derivative of CHS 828 was debrominated with tritium-gas using Pd/C catalyst to give [pyridyl -3,5- 3H2]-CHS 828 with a radiochemical purity of 99.3% and a specific activity of 1960 GBq/mmol. Similarly, the pyridyl-3-bromo derivative of the prodrug EB 1627 was debrominated with tritium-gas to give [pyridyl -3- 3H]-EB 1627 with a radiochemical purity of 98.1% and a specific activity of 894 GBq/mmol. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    Role of nitric oxide in downregulation of cytochrome P450 1a1 and NADPH: Quinone oxidoreductase 1 by tumor necrosis factor-, and lipopolysaccharide

    JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 10 2007
    Negar Gharavi
    Abstract We previously demonstrated that tumor necrosis factor alpha (TNF-,) and lipopolysaccharide (LPS) downregulate aryl hydrocarbon receptor (AhR)-regulated genes, such as cytochrome P450 1a1 (Cyp1a1) and NADPH: quinone oxidoreductase 1 (Nqo1) gene expression, yet the mechanisms involved remain unknown. The correlation between the inflammation-mediated suppression of AhR-regulated genes and the TNF-, or LPS-induced nitric oxide (NO) production especially in murine hepatoma Hepa 1c1c7 cells has been questioned; therefore we investigated whether NO is involved in the modulation of Cyp1a1 and Nqo1 by TNF-, or LPS in Hepa 1c1c7 cells. A significant dose-dependent increase in the inducible nitric oxide synthase (NOS2) expression and NO production were observed by various concentrations of TNF-, (1, 5, and 10 ng/mL) and LPS (1 and 5 µg/mL) which was completely inhibited by a NOS2 inhibitor, L-N6-(1-iminoethyl) lysine (L-NIL) (1 mM). Furthermore, TNF-, and LPS significantly induced NOS2 expression. Both TNF-, and LPS repressed the ,-naphthoflavone (,NF)-mediated induction of Cyp1a1 and Nqo1 at mRNA and activity levels. The downregulation of Cyp1a1, but not Nqo1, was significantly prevented by L-NIL. However, proxynitrite decomposer, iron tetrakis (N -methyl-4,-pyridyl) porphyrinato (FeTMPyP) (5 µM) did not affect TNF-,- and LPS-mediated downregulation of Cyp1a1 and Nqo1 at mRNA and activity levels. These results show that NO, but not peroxynitrite, may be involved in TNF-,- and LPS-mediated downregulation of Cyp1a1 without affecting the downregulation of Nqo1. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 96: 2795,2807, 2007 [source]

    Synthesis and properties of an ionic polyacetylene with aromatic heterocycles

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 23 2007
    Yeong-Soon Gal
    Abstract A new ionic polyacetylene with two aromatic heterocycles (pyridyl and thienyl) was prepared by the activation polymerization of 2-ethynylpyridine by using 3-(6-bromohexyloxy)methylthiophene without any additional initiator or catalyst. The activated acetylenic triple bond of N -substituted-2-ethynylpyridinium bromide, formed at first quaternarization process, was susceptible to linear polymerization. The instrumental analysis data on the polymer structure revealed that the polymer have the conjugated polyene backbone structure with the designed two aromatic heterocycles. The photoluminescence peak is located at 510 nm corresponding to a photon energy of 2.43eV. The electrochemical properties of this ionic polyacetylene were also measured and discussed. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5679,5685, 2007 [source]

    C,H···X (X = N, O, S) intramolecular interaction in 1-vinyl-2-(2,-heteroaryl)pyrroles as monitored by 1H and 13C NMR spectroscopy

    MAGNETIC RESONANCE IN CHEMISTRY, Issue 2 2002
    Andrei V. Afonin
    Abstract 1H and 13C NMR spectroscopy of a series of 1-vinyl-2-(2,-heteroaryl)-pyrroles were employed for the analysis of their electronic and spatial structure. The C,H···N intramolecular interaction between the ,-hydrogen of the vinyl group and the pyridine nitrogen, a kind of hydrogen bonding, was detected in 1-vinyl-2-(2,-pyridyl)pyrrole, which disappeared in its iodide methyl derivative. It was shown that this interaction is stronger than the C,H···O and C,H···S interactions in 1-vinyl-2-(2,-furyl)- and -2-(2,-thienyl)-pyrroles. Copyright © 2001 John Wiley & Sons, Ltd. [source]

    Cationic Hypericin Derivatives as Novel Agents with Photobactericidal Activity: Synthesis and Photodynamic Inactivation of Propionibacterium acnes

    PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 5 2009
    Beate Hager
    The present communication describes for the first time the synthesis and preliminary testing of two cationic hypericin derivatives. Uncharged hypericin derivatives with ,,,'-attached C2 -linkers leading to a pyridyl or a 4-dimethylaminophenyl residue were prepared and subsequently quaternized by means of iodomethane. Photobactericidal activity was assessed using Propionibacterium acnes. The quaternary N,N,N -trimethyl-anilinium derivative displayed a pronounced photodynamic inactivation of the bacteria at low incubation concentrations (<100 nm) and a short incubation time (1 h) after illumination with yellow light (590 nm, 20 J cm,2), whereas the photobactericidal efficacy of the N -methyl-pyridinium derivative was negligible under identical experimental conditions. [source]