Showing papers on "Hydrazone published in 2006"
TL;DR: A new fluorescent probe was synthesized and displayed selective Cu( II)-amplified absorbance and fluorescence emission above 500 nm in neutral buffered media and the detection of Cu(II) by 1 at a lower micromolar level was successful even in buffered water.
648 citations
TL;DR: The strong enhancement in the rate of hydrazone equilibration broadens the scope of this stable imine in the field of dynamic covalent chemistry.
Abstract: Aniline accelerates hydrazone formation and transimination through nucleophilic catalysis. To demonstrate the method, unprotected peptides are reacted and then scrambled using a hydrazone reaction under conditions relevant for biological applications. The strong enhancement in the rate of hydrazone equilibration broadens the scope of this stable imine in the field of dynamic covalent chemistry.
387 citations
TL;DR: Experimental results show that La (1), Sm (2), and Eu (4) complexes are better effective inhibitor for OH* than that of mannitol and indicates that the complexes have the activity to suppress O2-* and OH* and exhibit more effective antioxidants than ligand alone.
117 citations
TL;DR: Glyoxal bishydrazones 1 and pyridyl-hydrazone 2b were prepared and examined as a ligand for the Mizoroki−Heck cross-coupling reaction of aryl halides and olefin this article.
Abstract: Glyoxal bishydrazones 1 and pyridyl-hydrazone 2b were prepared and examined as a ligand for the Mizoroki−Heck cross-coupling reaction of aryl halides and olefin. We found that PdCl2(MeCN)2/hydrazone ligand 1e was a phosphine-free efficient catalyst system for a variety of substrates to produce the Mizoroki−Heck coupling products in good yields.
111 citations
Journal Article•
TL;DR: It was found that PdCl2(MeCN)2/hydrazone ligand 1e was a phosphine-free efficient catalyst system for a variety of substrates to produce the Mizoroki-Heck coupling products in good yields.
Abstract: Glyoxal bishydrazones 1 and pyridyl-hydrazone 2b were prepared and examined as a ligand for the Mizoroki−Heck cross-coupling reaction of aryl halides and olefin. We found that PdCl2(MeCN)2/hydrazone ligand 1e was a phosphine-free efficient catalyst system for a variety of substrates to produce the Mizoroki−Heck coupling products in good yields.
95 citations
TL;DR: Dynamic mixtures obtained by reversible covalent acylhydrazone formation of fragrance aldehydes and/or ketones and a hydrazide in water were found to be efficient delivery systems for the controlled release of highly volatile organic molecules.
85 citations
TL;DR: In this article, a new 1,2-dihydroquinazolin-4(3H)-one ligand, 2-[2-hydroxy-3-methoxyphenyl]-3]-2-hexyl-3]-methoxybenzylamino]-1, 2-Dihydronazolin 4(3h)-one (Hmpbaq), formed by the condensation of 2-aminobenzoylhydrazide with 2-hydroxymethylbenzaldehyde and its copper(II), nickel(
Abstract: A new 1,2-dihydroquinazolin-4(3H)-one ligand, 2-[2-hydroxy-3-methoxyphenyl]-3-[2-hydroxy-3-methoxybenzylamino]-1,2-dihydroquinazolin-4(3H)-one (Hmpbaq), formed by the condensation of 2-aminobenzoylhydrazide with 2-hydroxy-3-methoxybenzaldehyde and its copper(II), nickel(II), cobalt(II), manganese(II), zinc(II) and cadmium(II) complexes, have been synthesized. Their structures have been elucidated on the basis of elemental analyses, conductance measurements, magnetic moments, spectral (i.r., 1H-n.m.r., u.v.–vis., e.p.r. and FAB-mass) and thermal studies. The formation of 1,2-dihydroquinazolin-4(3H)-one rather than hydrazone in the reaction of 2-aminobenzoylhydrazide with 2-hydroxy-3-methoxybenzaldehyde is confirmed by the 1H-n.m.r. spectra and single crystal X-ray diffraction studies. The tridentate behavior of the ligand was proposed on the basis of spectral studies. X-band e.p.r. spectra of the copper(II) and manganese(II) complexes in the polycrystalline state at room temperature and liquid nitrogen temperature were recorded and their salient features are reported. Thermal stabilities of the manganese(II) and zinc(II) complexes have been studied.
76 citations
TL;DR: Palladium/copper-catalyzed Sonogashira cross-coupling reaction of aryl halides with a variety of terminal alkynes under amine-free conditions in dimethylformamide (DMF) at 80 degrees C gave internal arylated alkynes using PdCl2(MeCN)2 with phosphine- free hydrazone 2a as a ligand and CuI as the cocatalyst in good yields.
Abstract: Palladium/copper-catalyzed Sonogashira cross-coupling reaction of aryl halides with a variety of terminal alkynes under amine-free conditions in dimethylformamide (DMF) at 80 °C gave internal arylated alkynes using PdCl2(MeCN)2 with phosphine-free hydrazone 2a as a ligand and CuI as the cocatalyst in good yields. We also found PdCl2/hydrazone ligand 1d in PhMe at 80 °C was a phosphine-free efficient catalyst system for a Hiyama cross-coupling reaction of aryl bromides with aryl(trialkoxy)silanes in good yields.
76 citations
TL;DR: It is suggested that the complexes act as lipophilic transport shuttles that allow entrance to the cell and enable the delivery of both the ligand and metal which act in concert to inhibit proliferation.
Abstract: In an effort to better understand the antiproliferative effects of the tridentate hydrazone chelators di-2-pyridyl ketone isonicotinoyl hydrazone (HPKIH) and di-2-pyridyl ketone benzoyl hydrazone (HPKBH), we report the coordination chemistry of these ligands with the divalent metal ions, Mn, Co, Ni, Cu, and Zn. These complexes are compared with their FeII analogues which were reported previously. The crystal structures of Co(PKIH)2, Ni(PKIH)2, Cu(PKIH)2, Mn(PKBH)2, Ni(PKBH)2, Cu(PKBH)2, and Zn(PKBH)2 are reported where similar bis-tridenate coordination modes of the ligands are defined. In pure DMF, all complexes except the ZnII compounds exhibit metal-centered MIII/II (Mn, Fe, Co, Ni) or MII/I (Cu) redox processes. All complexes show ligand-centered reductions at low potential. Electrochemistry in a mixed water/DMF solvent only elicited metal-centered responses from the Co and Fe complexes. Remarkably, all complexes show antiproliferative activity against the SK-N-MC neuroepithelioma cell line similar to...
68 citations
TL;DR: 1,3,5-Trisacetoacetamidobenzene with three 1,3-diketo groups was synthesized by the reaction of 1,2,4-triaminobenzenes with diketene, and showed discotic nematic or columnar hexagonal mesophases.
60 citations
TL;DR: In this article, the authors compared the σ-donor ability of the imidazol-2-ylidene ligand with the presence of the N-dialkylamino group.
TL;DR: Quantum mechanical calculations indicate that of the conformational factors that could determine binding affinity, the planarity of the phenyl ring in relation to the central core and the conformation of the hydrazone chain may be the most influential.
TL;DR: In this paper, the authors describe the self-assembly processes as well as the structural and physico-chemical properties of [2×2]Zn2+4 grid complexes involving the bis-tridentate ligands 7−12, based on bis(hydrazone)pyrimidine complexation subunits and octahedrally coordinated Zn 2+ ions.
Abstract: We describe the self-assembly processes as well as the structural and physico-chemical properties of [2×2]Zn2+4 grid complexes involving the bis-tridentate ligands 7–12, based on bis(hydrazone)pyrimidine complexation subunits and octahedrally coordinated Zn2+ ions. The NMR spectroscopic data and the X-ray crystal structure results indicate that in solution and in the solid state the complexes 13–18 adopt a very compact arrangement providing stable [2×2] hydrazone-grid arrays. The π–π stacking between the phenyl ring and the hydrazone units of the perpendicular ligands in the complexes induces a perfect orthogonal arrangement suitable for applications in self-organized metallosupramolecular systems. Zinc complexes provide an opportunity to study the acid–base chemistry without the added effects due to paramagnetism or redox chemistry. The intermediate protonated grids undergo relatively rapid proton exchange on the NMR timescale, the presence of a sharp pyrimidine proton resonance suggesting that there is significant delocalization of the negative charge along the backbone of the ligand. Rotation of the phenyl ring is observed. It involves probably a mechanism in which one of the ligands partially dissociates allowing the initially intercalated phenyl group to rotate, before recoordination of the terminal pyridine. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
TL;DR: Observations show that the ligand favor energy transfers to the emitting energy level of Eu3+.
TL;DR: Chemoselective hydrazone formation between unprotected HYNIC-functionalized peptides and [(18)F]FB-CHO is a fast and straightforward radiolabeling method leading to high yields under mild acidic conditions and represents a powerful and versatile radioabeling strategy applicable to a variety of radionuclides and peptide precursors already available for (99m)Tc labeling.
TL;DR: The proposed intramolecular cyclization reaction involving doxorubicin's C-14 hydroxyl and the carboxylate-substituted hydrazone rationalizes the seemingly anomalous hydrolysis kinetics seen for hydraz one carboxyate linked doxorbicin, and provides a possible explanation for the poor antitumor activity exhibited by polymer-doxorubsicin conjugates utilizing this specific type of linkage.
TL;DR: These Mn-mediated conditions avoid toxic tin reagents and enable stereoselective intermolecular radical additions to C=N bonds with the broadest range of alkyl halides yet reported, including previously ineffective primary alkyL halides.
Abstract: Stereoselective radical additions have excellent potential as mild, nonbasic carbon−carbon bond constructions for direct asymmetric amine synthesis. Efficient intermolecular radical addition to CN bonds with acyclic stereocontrol has previously been limited mainly to secondary and tertiary radicals, a serious limitation from the perspective of synthetic applications. Here, we provide full details of the use of photolysis with manganese carbonyl to mediate stereoselective intermolecular radical addition to N-acylhydrazones. Photolysis (300 nm) of alkyl halides and hydrazones in the presence of Mn2(CO)10 and InCl3 as a Lewis acid led to reductive radical addition; diastereomer ratios ranged from 93:7 to 98:2 at ca. 35 °C. The reaction tolerates additional functionality in either reactant, enabling subsequent transformations as shown in an efficient asymmetric synthesis of coniine. A series of hydrazones bearing different substituents on the oxazolidinone auxiliary were compared; consistently high diastereoc...
TL;DR: It is concluded that the metal size is a key factor to control the nuclearity of the complexes derived from the hydrazone ligand 2,6-bis(1-salicyloylhydrazonoethyl)pyridine [H(4)daps].
Abstract: The influence of the metal size in the nuclearity of the complexes derived from the hydrazone ligand 2,6-bis(1-salicyloylhydrazonoethyl)pyridine [H4daps] has been investigated. We have synthesised a series of new complexes [M(Hxdaps)]·yH2O, (x = 2,3; y = 0–3) with M = Ag (1), Cd (2), Al (3), Sn (4) and Pb (6), using an electrochemical procedure. The crystal and molecular structures have been determined for the mononuclear complexes [Sn(H2daps)(H2O)2]·4H2O (5) and [Pb(H2daps)(CN)][Et4N] (7). Complex 5 is the first neutral Sn(II) complex derived from a pentadentate hydrazone Schiff base ligand. Complex 7 shows the lead coordinated to the hydrazone donor set and a cyanide ligand, being the first reported complex with the lead atom coordinated to a monodentate cyanide group. Additionally, we have synthesised the lead complex using chemical conditions, in the presence of sodium cyanide which allowed us to isolate the neutral complex [Pb(H2daps)] (8). Evaporation of these mother liquors led the novel compound [Pb(Hdaphs)(CH3COO)] (9). Complex 9 shows the initial ligand hydrolysed in one of the imine bonds giving rise to a new tetradentate ligand [H2daphs] coordinated to the lead atom and a bidentate acetate group. Moreover, the solution behaviour of the complexes has been investigated by 1H, 113Cd, 117Sn and 207Pb NMR techniques. In particular multinuclear NMR has provided new useful data to correlate factors such as oxidation state, coordination number and nature of the kernel donor atoms due to the new coordination found in complexes 5 and 7. The comparative study of the structures of the complexes derived from this pentadentate [N3O2] hydrazone ligand let us to conclude that the metal size is a key factor to control the nuclearity of the complexes derived from the ligand [H4daps].
TL;DR: In this paper, two novel bidentate Schiff base ligands, 2-(2-hydroxy-3,5-dichloro/diboromo) benzaldehyde-[4-(3-methyl-3-mesitylcyclobyl)-1,3-thiazol-2-yl]hydrazone, L1H, L2H and their transition metal complexes are reported.
Abstract: Two novel bidentate Schiff base ligands, 2-(2-hydroxy-3,5-dichloro/diboromo) benzaldehyde-[4-(3-methyl-3-mesitylcyclobutyl)-1,3-thiazol-2-yl]hydrazone, L1H, L2H and their transition metal complexes are reported. The new ligands and their complexes have been characterized by elemental analyses, ΛM, infrared, u.v.–vis, 1H- and 13C-n.m.r. spectroscopy, and magnetic susceptibility measurements. The thermal properties of all complexes have been investigated by TG technique. The complexes contain two monoanionic, bidentate NO ligands. It was found that all the complexes are mononuclear. Antimicrobial activities of the ligands and their complexes have been tested against five different microorganisms, and some of the complexes were found to be active against some of the microorganisms studied.
TL;DR: A compartmentalized {4 x[2 x 2]} Mn(II)16 antiferromagnetically coupled square grid results from the self-assembly reaction of a tetratopic pyridazine bis(hydrazone) ligand and Mn( II).
TL;DR: The La(III) complex with 1-phenyl-3-methyl-5-hydroxy-4-pyrazolyl phenyl ketone (PMBP)-isonicotinoyl hydrazone (La-complex) was synthesized in this article.
TL;DR: In this paper, azo-hydrazone tautomerism of Solophenyl red 3BL (C.I. Direct 80) polyazo dye was investigated using UV-visible, 1H NMR and steady-state fluorescence techniques.
TL;DR: In this article, cationic organoiron(II) pyranylideneacetaldehyde hydrazone complexes were prepared in high yields through condensation reactions of the organometallic hydrazine precursor [CpFe(η6-p-MeC6H4NHNH2)]+PF6- with differently substituted α- and γ-pyranylideacetaldehydes.
Abstract: New cationic organoiron(II) pyranylideneacetaldehyde hydrazone complexes were prepared in high yields through condensation reactions of the organometallic hydrazine precursor [CpFe(η6-p-MeC6H4NHNH2)]+PF6– with differently substituted α- and γ-pyranylideneacetaldehydes. The mononuclear hydrazones were stereoselectively obtained as their (E) isomers about the N=C double bond. All the new compounds were thoroughly characterized by a combination of elemental analysis and spectroscopic techniques (1H and 13C NMR, IR, and UV/Vis), and by a single-crystal X-ray diffraction analysis of the 2-tBu-chromene derivative 5. The spectroscopic data suggest that these complexes have a partial pyrylium character due to the electron-accepting ability of the cationic organometallic fragment and to the electron-releasing properties of the methylenepyran-based donor. The crystal structure of 5 shows that the η6-coordinated tolyl ring and the pyran ring are coplanar (dihedral angle 3.2°), a favorable situation that allows conjugation between the intracyclic oxygen atom and the cationic iron center through the entire hydrazone backbone. Compounds 4–6 are strongly polarized D–π–A systems that exhibit solvatochromic properties, low-lying intramolecular charge-transfer bands in their electronic absorption spectra, and enhanced second-order NLO properties (μβ), as measured by the EFISH technique at 1.907 μm. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
TL;DR: Tosyl- and Boc-hydrazones were found to be effective nucleophiles in the Mitsunobu reaction.
Abstract: Tosyl- and Boc-hydrazones were found to be effective nucleophiles in the Mitsunobu reaction. Tosyl hydrazones reacted cleanly with primary and secondary alcohols when co-administered to a cooled DBAD/PPh3 or DEAD/PPh3 complex. Boc-hydrazones required electron-withdrawing substituents to participate in the reaction.
TL;DR: While various 12-carboxamides were synthesized in moderate to high yields by using simple alkyl/arylamines or amino acid methylesters as N-nucleophiles, low yields can be achieved with alcohols as O-n nucleophiles.
TL;DR: The trifluoroacetate salt of cinachyramine (1) was isolated from the Okinawan sponge Cinachyrella sp. as mentioned in this paper, which is a novel alkaloid with an unprecedented cage system possessing a hydrazone and two aminals.
TL;DR: 3-Methylbutanal and hexanal, due to their low detection thresholds, could be important olfactive markers of these two products.
TL;DR: The reaction of NiCl(2).H(2)O with 1-benzotriazol-1-yl-[(p-X-phenyl)hydrazone]propan-2-one, X=H (HL(1)), X=Cl ( HL(2), X=Br (HL
TL;DR: Seven androgenic steroids have been converted into steroid hydrazones using Girard P hydrazine and analysed by electrospray ionisation multistage tandem mass spectrometry for recognition of common ions/fragmentation processes as well as analyte-specific transitions.
Abstract: Seven androgenic steroids have been converted into steroid hydrazones using Girard P hydrazine and analysed by electrospray ionisation multistage tandem mass spectrometry. The cationic derivatives 17alpha-testosterone hydrazone, 17beta-nortestosterone hydrazone, 17beta-bolasterone hydrazone, 17alpha-boldenone hydrazone, 17beta-fluoxymesterone hydrazone, 17alpha-trenbolone hydrazone and 4-chloroandrosten-3,17-dione hydrazone show good response in positive ion mode with enhancements for the method of up to 33 times relative to the native species. Detailed characterisation of fragmentation pathways reveals structurally specific ions formed by fragmentation of the hydrazine moiety. Comparison of structural similarities among the androgenic steroids allows recognition of common ions/fragmentation processes as well as analyte-specific transitions. The suitability of the derivatisation approach in the screening of heifer urine for the presence of administered hormones has been demonstrated using partially purified urine spiked with a mixture of androgenic steroids.
TL;DR: In this article, photo-oxidative fading of seven pyrazolinylazo dyes was examined by exposing the dyed cellulose films immersed in an aerobic aqueous Rose Bengal solution to a carbon arc.