Search results for "Pyridine"
showing 10 items of 2516 documents
Binding Sites for Ca2+‐Channel Effectors and Ryanodine inPeriplaneta americana—Possible Targets for New Insecticides
1996
The calcium channel and the 'calcium release channel' of muscle membrane of the cockroach Periplaneta americana have been characterized. Biological assays with calcium channel blockers and ryanodine on different insects and acari revealed pronounced insecticidal effects with ryanodine, but not with calcium channel blockers, at concentrations between 0.1 and 300 μg ml -1 . Skeletal muscle membranes derived either from the tubular network or from the sarcoplasmatic reticulum of P. americana were characterized with respect to the binding of the dihydropyridine (DHP) [ 3 H]isradipine (PN 200-110), the phenylalkylamine [ 3 H]verapamil and the alkaloid [ 3 H]ryanodine. Preliminary binding studies…
Enantioselective addition of nitromethane to α-keto esters catalyzed by copper(ii)–iminopyridine complexes
2008
The copper complex of a chiral iminopyridine easily prepared from (R)-(-)-fenchone and picolylamine catalyzes the enantioselective Henry (nitroaldol) reaction between nitromethane and alpha-keto esters. Good yields and modest to good enantioselectivities are obtained for a wide range of alpha-keto esters, bearing aromatic, alkyl or alkenyl groups attached to the ketone carbonyl group.
Enantioselective Henry addition of methyl 4-nitrobutyrate to aldehydes. Chiral building blocks for 2-pyrrolidinones and other derivatives.
2010
A catalytic highly enantioselective Henry addition of methyl 4-nitrobutyrate to aldehydes using a Cu(II)-amino pyridine complex as catalyst is described. The products resulting from this reaction constitute a new, highly versatile family of chiral building blocks as a result of the presence of three different functional groups on the molecule. These products have been transformed into nonracemic chiral gamma-lactams, 5-hydroxy-5-substituted levulinic acid derivatives, and delta-lactones.
Capping N‐Donor Ligands Modulate the Magnetic Dynamics of Dy III β‐Diketonate Single‐Ion Magnets with D 4 d Symmetry
2019
A family of four mononuclear DyIII β-diketonate complexes with formulas [Dy(tmhd)3 (Br2 -bpy) (1), [Dy(tmhd)3 (Br-bpy)] (2), [Dy(tmhd)3 (dppz)] (3), and [Dy(tmhd)3 (mcdpq)] (4) (tmhd=2,2,6,6-tetramethyl-3,5-heptanedione, Br2 -bpy=5,5'-dibromo-2,2'-bipyridine, Br-bpy=5-bromo-2,2'-bipyridine, dppz=dipyrido [3,2-a:2',3'-c]phenazine, mcdpq=2-methoxyl-3-cyanodipyrido[3,2-f:2,3'-h]quinoxaline) were prepared by modifying the capping N-donor coligands. DyIII centers in these complexes feature an N2 O6 octacoordinate environment with distorted square-antiprismatic D4d symmetry. Magnetic investigations evidenced single-ion magnet behavior in all complexes with energy barriers Ueff of 42.10 (1), 61.47…
Design of 3d–4f molecular squares through the [Fe{(HB(pz)3)}(CN)3]− metalloligand
2018
A new series of {FeIII2LnIII2} heterobimetallic squares of general formula [FeIII{HB(pz)3}(CN)(μ-CN)2Ln(pyim)x(NO3)2(H2O)y]2·zH2O [Ln = La (1), Gd (2), Tb (3) and Dy (4); {HB(pz)3}− = hydrotris(pyrazolyl)borate and pyim = 2-(1H-imidazol-2-yl)pyridine; x = 2, y = 0 (1), x = y = 1 (2–4) and z = 10 (1), 6 (2), 2.76 (3), 4 (4)] were synthesized by reacting the low-spin [FeIII{HB(pz)3}(CN)3]− complex anion with the preformed [LnIII(pyim)x(NO3)2(H2O)y]+ complex cation [formed in situ by mixing the lanthanide(III) salt and the pyim ligand]. Single-crystal X-ray diffraction shows that 1–4 crystallize in the P triclinic space group, 2–4 being isomorphous. In all cases, the structure comprises neutra…
White light emitting silsesquioxane based materials: the importance of a ligand with rigid and directional arms
2022
The synthesis of a novel polyhedral oligomeric silsesquioxane functionalized with eight rigid and directional terpyridine-based arms (Ter-POSS) was successfully achieved via a Sonogashira reaction. The POSS based ligand was extensively characterized using different techniques including 1H, 13C and 29Si NMR as well as UV-Vis and fluorescence spectroscopies. The assembly of these nano-caged units in the presence of different transition metal ions (Fe2+, Zn2+ and Cu2+) as well as of a cation from the lanthanides (Eu3+) was investigated using absorption and emission spectroscopies. The final materials display an evident emission in different regions of the visible spectrum as a function of the …
Mechanochemical synthesis of an Eu(III) complex. Preparation and Luminescence Properties of PMMA:[C42H38N5O19Eu] Hybrid Films
2015
Abstract Photoluminescent films of poly(methyl methacrylate), PMMA, doped with the complex [EuL2(H2O)2(NO3)3] were prepared, where L is the neutral ligand 2,6-bis[2-formylphenoxymethyl]pyridine (C21H17NO4). The Eu(III) complex was synthesized by classic chemosynthesis, and also through a solvent-free mechanochemical synthesis, and characterized by spectroscopy, thermal analysis (TGA and DTA), and single crystal X-ray diffraction. The mechanochemical route improves the yield for the complex, which is synthesized over times considerably shorter compared to the traditional synthesis, and through a solvent-free procedure. The photoluminescent properties of the Eu(III) complex and hybrid films P…
Repeated exposure of fluazinam fungicides affects gene expression profiles yet carries no costs on a nontarget pest
2021
Fungicides are used to control pathogenic fungi of crop species, but they have also been shown to alter behavioral, life history and fitness related traits of non-target insects. Here, we tested the fungicide effects on feeding behavior, survival and physiology of the non-target pest insect, the Colorado potato beetle (Leptinotarsa decemlineata). Feeding behavior was studied by a choice test of adult beetles, which were allowed to choose between a control and a fungicide (fluazinam) treated potato leaf. Larval survival was recorded after 24-hour and 72-hour exposure to control and fungicide-treated leaves with two different concentrations. The adults did not show fungicide avoidance behavio…
HSP27 controls GATA-1 protein level during erythroid cell differentiation.
2010
AbstractHeat shock protein 27 (HSP27) is a chaperone whose cellular expression increases in response to various stresses and protects the cell either by inhibiting apoptotic cell death or by promoting the ubiquitination and proteasomal degradation of specific proteins. Here, we show that globin transcription factor 1 (GATA-1) is a client protein of HSP27. In 2 models of erythroid differentiation; that is, in the human erythroleukemia cell line, K562 induced to differentiate into erythroid cells on hemin exposure and CD34+ human cells ex vivo driven to erythroid differentiation in liquid culture, depletion of HSP27 provokes an accumulation of GATA-1 and impairs terminal maturation. More spec…