- Selective sensing of Fe3+ based on fluorescence quenching by 2,6-bis(benzoxazolyl)pyridine with β-cyclodextrin in neutral aqueous solution
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A selective and sensitive fluorescent chemosensor (BBOZP-CD) for Fe3+ was composed of water-soluble β-cyclodextrins and 2,6-bis(benzoxazolyl)pyridine which was synthesized through the reaction of 2,6-pyridinedicarboxylic acid and o-aminophenol catalyzed by polyphosphoric acid under microwave irradiation. The chemosensor BBOZP-CD for metal ions were carefully investigated by fluorescent quenching in present of metal ions. The result showed BBOZP-CD chemosensor was remarkable fluorescence quenching and a highly selectivity and sensitivity for Fe3+ in neutral aqueous solution, and the other common metal ions did not notably disturb the detection of Fe3+. Additionally, the effect of pH to the chemosensor for Fe3+ was also studied. The result indicated the respond signals of BBOZP-CD to Fe3+ was stable and hardly influenced while the pH value was greater than 3.6.
- Feng, Liheng,Chen, Zhaobin,Wang, Duosheng
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- Palladium(II) complexes of tridentate bis(benzazole) ligands: Structural, substitution kinetics, DNA interactions and cytotoxicity studies
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Reactions of 2,6-bis(benzimidazol-2-yl)pyridine (L1), 2,6-bis(benzoxazol-2-yl)pyridine (L2), and 2,6-bis(benzothiazol-2-yl)pyridine (L3) with [Pd(NCMe)2Cl2] in the presence of NaBF4 afforded the corresponding Pd(II) complexes, [Pd(L1)Cl]BF4, PdL1; [Pd(L2)Cl]BF4, PdL2; [Pd(L3)Cl]BF4, PdL3; respectively, while reaction of bis[(1H-benzimidazol-2-yl)methyl]amine (L4) with [Pd(NCMe)2Cl2] afforded complex [Pd(L4)Cl]Cl, PdL4. Characterisation of the complexes was accomplished using NMR, IR, MS, elemental analyses and single crystal X-ray crystallography. Ligand substitution kinetics of these complexes by biological nucleophiles thiourea (Tu), L-methionine (L-Met) and guanosine 5′-diphosphate disodium salt (5-GMP) were examined under pseudo-first order conditions. The reactivity of the complexes decreased in the order: PdL1 > PdL2 > PdL3 > PdL4, ascribed to electronic effects. Density functional theory (DFT) supported this trend. Studies of interaction of the Pd(II) complexes with calf thymus DNA (CT-DNA) revealed strong binding affinities via intercalative binding mode. Molecular docking studies established associative non-covalent interactions between the Pd complexes and DNA. The in vitro cytotoxic activities of PdL1–PdL4 were assessed in cancer cell lines HeLa and MRC5-SV2 and a normal cell line MRC-5, using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. PdL1 exhibited cytotoxic potency and selectivity against HeLa cell that was comparable to cisplatin's. Complex PdL1, unlike cisplatin, did not significantly induce caspase-dependent apoptosis.
- Bellam, Rajesh,Fatokun, Amos A.,Jaganyi, Deogratius,Ojwach, Stephen O.,Omondi, Reinner O.
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- Polycyclic pyridines as potassium ion channel modulators
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The present invention provides a genus of polycyclic pyridines that are useful as modulators of potassium ion channels. The modulators of the invention are of use in both therapeutic and diagnostic methods.
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Page/Page column 14
(2008/06/13)
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- Separation of lanthanides and actinides(III) using tridentate benzimidazole, benzoxazole and benzothiazole ligands
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The ability of new hydrophobic tridentate ligands based on 2,6-bis(benzimidazol-2-yl)pyridine, 2,6-bis(benzoxazol-2-yl)pyridine and 2,6-bis(benzothiazol-2-yl)pyridine to selectively extract americium(III) from europium(III) was measured. The most promisin
- Drew, Michael G. B.,Hill, Clement,Hudson, Michael J.,Iveson, Peter B.,Madic, Charles,Vaillant, Ludovic,Youngs, Tristan G. A.
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p. 462 - 470
(2007/10/03)
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- Models for Copper-Dioxygen Complexes: the Chemistry of Copper(II) with Some Planar Tridentate Nitrogen Ligands
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The solution chemistry of Cu(II) with a series of five planar tridentate nitrogen ligands, 2,6-bis(benzimidazol-2-yl)pyridine (bzimpy, 1), 2,6-bis(1-methylbenzimidazol-2-yl)pyridine (mbzimpy, 2), 2,6-bis(benzothiazol-2-yl)pyridine (bzthpy, 3), 2,6-bis(benzoxazol-2-yl)pyridine (bzoxpy, 4), and 2,2',6',2"-terpyridyl (terpy, 5) is reported.Electronic and EPR spectra are consistent with the complexes 2+ having essentially tetragonal structure in solution, with the fourth coordination site in the plane of the ligand occupied by solvent. bzthpy and bzoxpy show smaller ligand-field splittings than bzimpy, mbzimpy, and terpy, and are easily decomplexed from the copper.Substitution of the coordinated solvent molecule in the plane of the ligand is observed with Cl- and OH- (provided that the ligand has no acidic protons) for all ligands except terpy.The reaction between 2+ and imidazole has been studied by potentiometric titration in MeCN/H2O 1:1 and shows strong binding of the imidazole in the plane (log K = 4.5 at 25 deg C), and also the formation of an imidazolate-bridged dinuclear species.
- Piguet, Claude,Bocquet, Bernard,Mueller, Edgar,Williams, Alan F.
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p. 323 - 337
(2007/10/02)
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- Eine einfache Methode zur Herstellung von Benzoxazolen
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The preparation of benzoxazoles by a facile one-pot reaction is reported.The reaction of carboxylic acids with 2-chloro-N-methyl-Δ1-pyrrolinium chloride in an excess of N-methyl-2-pyrrolidone afforded carboxylic acid chlorides which were converted subsequently to their 2-hydroxyanilides by addition of 2-aminophenols.Cyclization of the 2-hydroxy-anilides at elevated temperatures furnished the benzoxazoles in high yield and purity.
- Seha, Zdenek,Weis, Claus D
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p. 413 - 419
(2007/10/02)
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