- Synthesis and transition metal coordination chemistry of a novel hexadentate bispidine ligand
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Reported is the new bispidine-derived hexadentate ligand L (L = 3-(2-methylpyridyl)-7-(bis-2-methylpyridyl)-3,7-diazabicyclo[3.3.1]nonane) with two tertiary amine and four pyridine donor groups. This ligand can form heterodinuclear and mononuclear complexes and, in the mononuclear compounds discussed here, the ligand may coordinate as a pentadentate ligand, with one of the bispyridinemethane-based pyridine groups un- or semi-coordinated, or as a hexadentate ligand, leading to a pentagonal pyramidal coordination geometry or, with an additional monodentate ligand, to a heptacoordinate pentagonal bipyramidal structure. The solution and solid state data presented here indicate that, with the relatively small CuII and high-spin FeII ions the fourth pyridine group is only semi-coordinated for steric reasons and, with the larger high-spin MnII ion genuine heptacoordination is observed but with a relatively large distortion in the pentagonal equatorial plane. This journal is
- Comba, Peter,Rudolf, Henning,Wadepohl, Hubert
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- Synthesis, spectra and X-ray crystallography of dipyridin-2-ylmethanone oxime and its CuX2(oxime)2 complexes: Thermal, Hirshfeld surface and DFT analysis
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Dipyridin-2-ylmethanone oxime (C11H9N3O), was prepared using di-2-pyridyl ketone. The oxime ligand and its neutral CuX2 (oxime)2 (X = Cl or Br) complexes have been identified with the aid of several spectroscopic techniques such as: IR, EI-MS, EA, UV–visible, TG, 1H-NMR and finally the structure of the free oxime ligand was confirmed by X-ray diffraction studies. The oxime crystallizes in the monoclinic space group P21/c, with cell parameters a = 8.8811 (8) ? b = 10.6362 (8) ? c = 11.2050 (8) ? β = 109.085 (4) o V = 1000.26 (14) ?3 and Z = 4. The molecular conformation is stabilized by a strong intramolecular O–H?N hydrogen bonding between the hydroxyl group of the oxime moiety and the nitrogen of the pyridine ring. Since the oxime structure was solved by XRD, the ligand structure parameters like bond length and angles were compared to the DFT computed one, the UV–visible to TD-SCF and Hirshfeld surface to MEP analysis.
- Warad, Ismail,Abdoh, Muneer,Al Ali, Anas,Shivalingegowda, Naveen,Kumara, Karthik,Zarrouk, Abdelkader,Lokanath, Neartur Krishnappagowda
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- Hybrid organic-inorganic materials from di-(2-pyridyl)methylamine-palladium dichloride complex as recoverable catalysts for Suzuki, Heck and Sonogashira reactions
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Hybrid silica materials containing the di-(2-pyridyl)methylamine-palladium dichloride complex, prepared by sol-gel cogelification, are efficient recyclable catalysts for Suzuki (aryl bromides and chlorides), Heck (aryl bromides) and Sonogashira reactions (aryl iodides and bromides). Formation of palladium(0) nanoparticles is observed in the Suzuki and Heck reactions but not in the Sonogashira coupling.
- Trilla, Montserrat,Pleixats, Roser,Man, Michel Wong Chi,Bied, Catherine,Moreau, Joel J. E.
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- Electrochemical polymerization of iron(III) polypyridyl complexes through C-C coupling of redox non-innocent phenolato ligands
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Phenolato moieties impart redox flexibility to metal complexes due their accessible (oxidative) redox chemistry and have been proposed as functional ligand moieties in redox non-innocent ligand based transition metal catalysis. Here, the electro- and spectroelectrochemistry of phenolato based μ-oxodiiron(III) complexes [(L1)Fe(μ-O)Fe(L1)]2+ (1) and [(L2)Fe-(μ-O)Fe(L2)]2+ (2), where L1 = 2-(((di(pyridin-2-yl)methyl)-(pyridin-2-ylmethyl)amino)methyl)phenol and L2 = 3, 5-di-tert-butyl-2-(((di(pyridin-2-yl)methyl)(pyridin-2-ylmethyl)amino)-methyl)phenol, is described. The electrochemical oxidation of 1 in dichloromethane results in aryl C-C coupling of phenoxyl radical ligand moieties to form tetra nuclear complexes, which undergo subsequent oxidation to form iron(III) phenolato based polymers (poly-1). The coupling is blocked by placing tert-butyl groups at para and ortho positions of phenol units (i.e., 2). Poly-1 shows two fully reversible redox processes in monomer free solution. Assignment of species observed during the electrochemical and chemical {(NH4)2[CeIV(NO3)6]} oxidation of 1 in acetonitrile is made by comparison with the UV-vis-NIR absorption and resonance micro-Raman spectroelectrochemistry of poly-1, and by DFT calculations, which confirms that oxidative coupling occurs in acetonitrile also. However, in contrast to that observed in dichloromethane, in acetonitrile, the oligomers formed are degraded in terms of a loss of the Fe(III)-O-Fe(III) bridge by protonation. The oxidative redox behavior of 1 and 2 is, therefore, dominated by the formation and reactivity of Fe(III) bound phenoxyl radicals, which considerably holds implications in regard to the design of phenolato based complexes for oxidation catalysis.
- Unjaroen, Duenpen,Swart, Marcel,Browne, Wesley R.
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- Interplay Between Steric and Electronic Effects: A Joint Spectroscopy and Computational Study of Nonheme Iron(IV)-Oxo Complexes
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Iron is an essential element in nonheme enzymes that plays a crucial role in many vital oxidative transformations and metabolic reactions in the human body. Many of those reactions are regio- and stereospecific and it is believed that the selectivity is guided by second-coordination sphere effects in the protein. Here, results are shown of a few engineered biomimetic ligand frameworks based on the N4Py (N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine) scaffold and the second-coordination sphere effects are studied. For the first time, selective substitutions in the ligand framework have been shown to tune the catalytic properties of the iron(IV)-oxo complexes by regulating the steric and electronic factors. In particular, a better positioning of the oxidant and substrate in the rate-determining transition state lowers the reaction barriers. Therefore, an optimum balance between steric and electronic factors mediates the ideal positioning of oxidant and substrate in the rate-determining transition state that affects the reactivity of high-valent reaction intermediates.
- Mukherjee, Gourab,Alili, Aligulu,Barman, Prasenjit,Kumar, Devesh,Sastri, Chivukula V.,de Visser, Sam P.
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- Near-infrared fluorescent compound, preparation method and application thereof in detection of ferrous ions
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The invention provides a near-infrared fluorescent compound, a preparation method and application of the near-infrared fluorescent compound in detection of ferrous ions. The near-infrared fluorescentcompound provided by the invention can enable a fluorescence probe of Fe to have a maximum excitation emission wavelength reaching a near-infrared region, and has good selectivity to the Fe .
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Paragraph 0043-0047
(2019/12/25)
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- Aromatic-ring-containing compound, preparation method thereof, pharmaceutical composition and application thereof
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The invention discloses an aromatic-ring-containing compound, a preparation method thereof, a pharmaceutical composition and application. The present invention provides the aromatic-ring-containing compound represented by a formula 1, a pharmaceutically acceptable salt thereof, a stereoisomer thereof, a tautomer thereof or a solvate thereof, and the aromatic-ring-containing compound can be effectively bounded to bromodomains of BRD4, BRD3, BRD2, and BRDT in BET family to regulate transcription of downstream gene c-myc and related target genes of the c-myc so as to regulate downstream signalingpathways to play specific roles including treatment of diseases such as inflammatory diseases, cancer, and AIDS. Some of the compounds have high activity, and have good cell activity and metabolic stability, so that the compounds can be an effective drug for treating tumors.
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Paragraph 0602-0606
(2018/08/03)
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- Selective C-H halogenation over hydroxylation by non-heme iron(iv)-oxo
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Non-heme iron based halogenase enzymes promote selective halogenation of the sp3-C-H bond through iron(iv)-oxo-halide active species. During halogenation, competitive hydroxylation can be prevented completely in enzymatic systems. However, synthetic iron(iv)-oxo-halide intermediates often result in a mixture of halogenation and hydroxylation products. In this report, we have developed a new synthetic strategy by employing non-heme iron based complexes for selective sp3-C-H halogenation by overriding hydroxylation. A room temperature stable, iron(iv)-oxo complex, [Fe(2PyN2Q)(O)]2+ was directed for hydrogen atom abstraction (HAA) from aliphatic substrates and the iron(ii)-halide [FeII(2PyN2Q)(X)]+ (X, halogen) was exploited in conjunction to deliver the halogen atom to the ensuing carbon centered radical. Despite iron(iv)-oxo being an effective promoter of hydroxylation of aliphatic substrates, the perfect interplay of HAA and halogen atom transfer in this work leads to the halogenation product selectively by diverting the hydroxylation pathway. Experimental studies outline the mechanistic details of the iron(iv)-oxo mediated halogenation reactions. A kinetic isotope study between PhCH3 and C6D5CD3 showed a value of 13.5 that supports the initial HAA step as the RDS during halogenation. Successful implementation of this new strategy led to the establishment of a functional mimic of non-heme halogenase enzymes with an excellent selectivity for halogenation over hydroxylation. Detailed theoretical studies based on density functional methods reveal how the small difference in the ligand design leads to a large difference in the electronic structure of the [Fe(2PyN2Q)(O)]2+ species. Both experimental and computational studies suggest that the halide rebound process of the cage escaped radical with iron(iii)-halide is energetically favorable compared to iron(iii)-hydroxide and it brings in selective formation of halogenation products over hydroxylation.
- Rana, Sujoy,Biswas, Jyoti Prasad,Sen, Asmita,Clémancey, Martin,Blondin, Geneviève,Latour, Jean-Marc,Rajaraman, Gopalan,Maiti, Debabrata
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p. 7843 - 7858
(2018/10/31)
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- Mechanistic elucidation of C-H oxidation by electron rich non-heme iron(IV)-oxo at room temperature
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Non-heme iron(iv)-oxo species form iron(iii) intermediates during hydrogen atom abstraction (HAA) from the C-H bond. While synthesizing a room temperature stable, electron rich, non-heme iron(iv)-oxo compound, we obtained iron(iii)-hydroxide, iron(iii)-alkoxide and hydroxylated-substrate-bound iron(ii) as the detectable intermediates. The present study revealed that a radical rebound pathway was operative for benzylic C-H oxidation of ethylbenzene and cumene. A dissociative pathway for cyclohexane oxidation was established based on UV-vis and radical trap experiments. Interestingly, experimental evidence including O-18 labeling and mechanistic study suggested an electron transfer mechanism to be operative during C-H oxidation of alcohols (e.g. benzyl alcohol and cyclobutanol). The present report, therefore, unveils non-heme iron(iv)-oxo promoted substrate-dependent C-H oxidation pathways which are of synthetic as well as biological significance.
- Rana, Sujoy,Dey, Aniruddha,Maiti, Debabrata
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supporting information
p. 14469 - 14472
(2015/09/28)
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- Effective conversion of heteroaromatic ketones into primary amines via hydrogenation of intermediate ketoximes
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A process to access heteroaromatic primary amines from the corresponding heteroaromatic ketones has been developed. A broad range of previously reported methods to convert ketones to primary amines was examined on heterocyclic ketones without success, including Leuckart-Wallach conditions, borane reductions, and transition-metal-catalyzed hydrogenations. Unique among the catalysts examined, Raney cobalt produced the desired primary heterocyclic amine. Raney cobalt hydrogenation of structurally varied heterocyclic ketoximes was demonstrated to form primary amines in good selectivity under mild conditions, and the products are easily isolated in high yield. Additionally, this is the first report of a systematic evaluation of the capabilities of Raney cobalt as an oxime hydrogenation catalyst.
- Baucom, Kyle D.,Guram, Anil S.,Borths, Christopher J.
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supporting information
p. 201 - 204
(2015/03/03)
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- METHOD FOR PRODUCING N,N-BIS(PYRIDIN-2-YL-METHYL)-1,1-BIS(PYRIDIN-2-YL)-1-AMINOALKANE COMPOUNDS AND METAL COMPLEX SALTS CONTAINING THESE COMPOUNDS
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The invention relates to a method for producing the compositions cited in the title. According to this method: dipyridyl ketone is reacted with hydroxylamine; the oxime obtained thereby is reduced without intermediate isolation to form 1,1-di-(2-pyridyl)-methylamine, and; this amine is firstly reacted with 1 to 1.5 molar equivalent of picolyl chloride and then with another 1 to 1.5 molar equivalent of picolyl chloride to form the amine of formula (I). This amine is purified via the tetrafluoroborate salt and subsequently alkylated with an alkyl iodide. This method represents an improvement with regard to prior art methods for producing these compounds.
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Page/Page column 1; 4; 7-8
(2008/06/13)
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- Di-2-pyridylmethylamine-based palladium complexes as new catalysts for Heck, Suzuki, and Sonogashira reactions in organic and aqueous solvents
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(Matrix presented) A new palladium-dipyridylmethylamine complex is an excellent catalyst for C-C bond-forming processes such as the Heck, Suzuki, and Sonogashira reactions in organic and aqueous solvents under homogeneous conditions.
- Najera, Carmen,Gil-Molto, Juan,Karlstroem, Sofia,Falvello, Larry R.
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p. 1451 - 1454
(2007/10/03)
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