- Lanthanide triple helical complexes with a chiral bis(benzimidazole)pyridine derivative
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The ligand neopentyl 2,6-bis[(1-methylbenzimidazol-2-yl)]-pyridine-4-carboxylate (L12) has been synthesised to test the effect of the chiral neopentyl ester group in the 4-position of the pyridine ring on (i) the helical wrapping, (ii) the diastereomeric induction and (iii) the thermodynamic and photophysical properties of the [Ln(L12)3]3+ complexes. The crystal structure of ligand L12 shows the expected trans-trans conformation of the tridentate binding unit. The ligand forms stable 1:3 complexes in anhydrous acetonitrile (logβ3 in the range 17.3-19.0, logK3 in the range 2.9-4.6). The triple helical structure in solution is responsible for the four times larger specific rotary dispersion measured in the complexes. Circularly polarised luminescence of the Eu triple helical complex displays a weak effect, suggesting a small diastereomeric excess in solution. Ligand L12 appears to favour a 37ππ*-to-Ln energy transfer process for Eu, but temperature-dependent nonradiative processes lead to a very small quantum yield. High-resolution luminescence spectra indicate that the Eu complex has a distorted D3 local symmetry at the metal ion site. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002).
- Muller, Gilles,Riehl, James P.,Schenk, Kurt J.,Hopfgartner, Gerard,Piguet, Claude,Buenzli, Jean-Claude G.
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- Synthesis, crystal structure, and antioxidant property of a new Co(III) coordination polymer based on ligand (E)-2-{2-[1-(1-methyl-1H-benzo[d]imidazol-2-yl)ethylidene]hydrazinyl}benzo[d]thiazole
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A new Co(III) complex, [CoL2](ClO4)(CH3CN) (1) (HL = (E)-2-{2-[1-(1-methyl-1H-benzo[d]imidazol-2-yl)ethylidene]hydrazinyl}benzo[d]thizole), has been prepared by solvent evaporation method, and characterized by single-crystal X-ray diffraction, bond valence sum, and elemental analysis. The result of single-crystal X-ray diffraction analysis indicates that each Co(III) ion is six-coordinated by six nitrogen atoms from two L- to form distorted octahedral geometry. The hydrogen bonds and π.π stacking interactions ensure the cohesion of crystal lattice in a 3D supramolecular framework in the solid state. The antioxidant activities of HL and 1 were also studied.
- Deng, Wen-Ting,Liu, Jia-Cheng,Cao, Ping,Xu, Ya-Qin
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p. 667 - 672
(2015/04/16)
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- Synthesis and in vitro antifungal evaluation of benzoimidazolyl-piperazinyl-phenylmethanone derivatives
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Benzimidazole and piperazines are the important pharmacophores in the structures of many antifungal compounds. Further, the phenylmethanone are also a unique class of compounds whose antifungal profile is not much exploited. So to exploit their antifungal potential we have selected these three combinations and framed the novel parent structure for our research work. In this study a novel series of benzimidazoles derivatives was synthesized by microwave irradiation and characterized by 1H NMR, 13C NMR, Infra Red (IR), and Mass Spectroscopy (MS), and by elemental analysis. The screening of compound for in vitro (turbidimetric method) antifungal activity against C.albicans revealed activity in many of the compounds as comparable to that of ketoconazole.
- Kankate, Rani S.,Gide, Parag S.,Belsare, Deepak P.
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p. 1855 - 1863
(2015/04/22)
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- Synthesis and antiprotozoal activity of novel 1-methylbenzimidazole derivatives
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In this paper are reported the synthesis and antiprotozoal activity in vitro of 24 1-methylbenzimidazole derivatives (13-36) substituted at position 2 with aminocarbonyl, N-methylaminocarbonyl, N,N-dimethylaminocarbonyl, ethoxycarbonyl, 1-hydroxyethyl and acetyl groups, some of them with chlorine atoms at the benzenoid ring. Compounds 13-36 were more active than metronidazole, the choice drug against Giardia intestinalis and most of them against Trichomonas vaginalis. The most active group of compounds for both parasites was that with a 2-ethoxycarbonyl group (16, 22, 28, 34), independently of the substitution pattern at the benzenoid ring.
- Valdez-Padilla, David,Rodriguez-Morales, Sergio,Hernandez-Campos, Alicia,Hernandez-Luis, Francisco,Yepez-Mulia, Lilian,Tapia-Contreras, Amparo,Castillo, Rafael
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experimental part
p. 1724 - 1730
(2009/08/08)
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- Alternate method for the synthesis of N-alkyl/aralkyl-2-(α-hydroxy alkyl/aralkyl)benzimidazoles via regiospecific acetylation
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Acetylation of 1H-2-(α-hydroxyalkyl/aryl)benzimidazoles 2 with Ac2O results in the regiospecific formation of O-acetoxy derivative 3, which on alkylation with alkylating agents in nonaqueous media under phase-transfer catalytic conditions affords N-alkyl
- Dubey,Reddy, P.V.V. Prasada,Srinivas
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p. 1675 - 1681
(2008/02/01)
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- Investigations of unsaturated azoles. 13. Synthesis and some reactions of 1-alkylbenzimidazoles
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Methods of direct alkylation of benzimidazoles by haloalkanes in homogeneous medium and under phase transfer catalysis conditions together with cyanoethylation by acrylonitrile are reported. The dealkylation of quaternary benzimidazole salts was also studied. 1997 Plenum Publishing Corporation.
- Popov
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p. 672 - 681
(2007/10/03)
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- Acidity Constants of Benzimidazolium Ketone and Pyridinium Aldehyde Hydrates
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Acidity constants (pKa) of the hydroxyl groups of the quaternary heterocyclonium carbinols 2-hydroxymethyl-1-methylpyridinium and 2-(1-hydroxyethyl)-1,3-dimethylbenzimidazolium ions are 11.5 +/- 0.5.Acidity constants of the corresponding gem diols, the hydrates of 2-formyl-1-methylpyridinium and 2-acetyl-1,3-dimethylbenzimidazolium ions hence are estimated to be 9 +/- 0.5.Accordingly, acidity constants of the hydroxyl groups of pyridine aldehyde salt hydrates are 12-13, not 4-5 as previously reported; and conversely, acidity constants of the pyridinium groups are 4-5, not 12-13.
- Owen, Terence C.
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p. 987 - 990
(2007/10/02)
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