- New artificial biomimetic enzyme analogues based on Iron(II/III) schiff base complexes: An effect of (Benz)imidazole organic moieties on phenoxazinone synthase and DNA recognition
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Elucidation of the structure and function of biomolecules provides us knowledge that can be transferred into the generation of new materials and eventually applications in e.g., catalysis or bioassays. The main problems, however, concern the complexity of the natural systems and their limited availability, which necessitates utilization of simple biomimetic analogues that are, to a certain degree, similar in terms of structure and thus behaviour. We have, therefore, devised a small library of six tridentate N-heterocyclic coordinating agents (L1–L6), which, upon complexation, form two groups of artificial, monometallic non-heme iron species. Utilization of iron(III) chloride leads to the formation of the 1:1 (Fe:Ln) ‘open’ complexes, whereas iron(II) trifluoromethanosulfonate allows for the synthesis of 1:2 (M:Ln) ‘closed’ systems. The structural differences between the individual complexes are a result of the information encoded within the metallic centre and the chosen counterion, whereas the organic scaffold influences the observed properties. Indeed, the number and nature of the external hydrogen bond donors coming from the presence of (benz)imidazole moieties in the ligand framework are responsible for the observed biological behaviour in terms of mimicking phenoxazinone synthase activity and interaction with DNA.
- Bocian, Aleksandra,Brykczyńska, Daria,Fik-Jaskó?ka, Marta A.,Gorczyński, Adam,Kubicki, Maciej,Patroniak, Violetta,Roviello, Giovanni N.,Szymańska, Martyna,Wa??sa-Chorab, Monika
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- Dioxygen Activation by an in situ Reduced CuII Hydrazone Complex
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A CuII hydrazone complex has been synthesized that can be reduced in situ in boiling methanol to give the corresponding CuI complex. The latter complex readily activates dioxygen under ambient conditions, as was unambiguously shown by isotopic labeling studies. As a consequence of the dioxygen activation, the thienyl moiety appended to the hydrazone ligand is easily oxidized in β position (C-H→C-O), finally leading to a change in the coordination environment of the central metal ion. All relevant complexes have been structurally characterized by single-crystal X-ray diffraction analyses. The hydrazone ligand applied in this study does not mimic a biologically relevant coordination motif in copper-containing oxygenases. Nonetheless, the reactivity of the CuI complex resembles that found in many oxygenases, indicating that hydrazone ligands may be well-suited for the generation of novel bioinspired oxidation catalysts. A CuII complex of a hydrazone ligand with N,N,S-donor functionality is reported that, after in situ reduction, is able to activate dioxygen, leading to a hydroxylation of the ligand and finally resulting in the formation of a CuII complex of a hydrazone ligand acting as an N,N,O-donor.
- Radunsky, Christian,K?sters, Jutta,Letzel, Matthias C.,Yogendra, Sivathmeehan,Schwickert, Christian,Manck, Sinja,Sarkar, Biprajit,P?ttgen, Rainer,Weigand, Jan J.,Neugebauer, Johannes,Müller, Jens
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- Supramolecular Control of the Template-Induced Selective Photodimerization of 4-Methyl-7-O-hexylcoumarin
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A symmetric ditopic molecular receptor (3), containing two identical hydrogen-bonding recognition subunits, was designed and synthesized. These subunits are capable of binding substrates with complementary donor and acceptor sites to form a supramolecular complex through hydrogen bonding, Receptor 3 was designed to accept two guest molecules, which are held in close proximity within the supramolecular species. The substrate molecule, 4-methyl-7-O-hexylcoumarin (1c), forms a 2:1 complex with a binding constant of 150M-1 for the second substrate, passing first through a 1:1 complex with an affinity constant of 510M-1. The orientation of two molecules of 1c when bound to the template leads to the selective formation of the trans-syn [2+2] photoproduct 2cB upon irradiation. Other photoproducts typically produced in the absence of the template are suppressed.
- Skene, William G.,Couzigne, Emilie,Lehn, Jean-Marie
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- Mono and dinuclear iridium(iii) complexes featuring bis-tridentate coordination and Schiff-base bridging ligands: The beneficial effect of a second metal ion on luminescence
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The synthesis and photophysical properties of a set of iridium(iii) complexes featuring tridentate N^N^O-coordinating ligands are described, of generic structure [Ir(N^C^N-dpyx)(N^N^O-Ln)]+ (n = 1 to 4) (dpyx = 1,3-dipyridyl-4,6-dimethylbenzene). The proligands HLn are Schiff bases synthesised by condensation of salicylaldehydes with N-methyl-hydrazinopyridines: they are able to coordinate to the Ir(iii) via lateral pyridine-N and phenolate-O- atoms and a central hydrazone-N atom; the four examples differ in the substitution pattern within the phenolate ring. The bis-tridentate coordination is confirmed by X-ray diffraction. The complexes are phosphorescent in solution at ambient temperature, with higher quantum yields and longer lifetimes than those of structurally related bis-cyclometallated complexes with an N^N^C-coordinating ligand. Related proligands H2L5 and H2L6 have been prepared from 4,6-bis(1-methyl-hydrazino)pyrimidine. They feature a central pyrimidine and two N^N^O units. They are shown to bind as ditopic, bis-tridentate ligands with two iridium(iii) ions, leading to unprecedented dinuclear complexes of the form [{Ir(N^C^N)}2(O^N^N-N^N^O-Ln)]2+ (n = 5, 6; N^C^N = dpyx or 1,3-dipyridyl-4,6-difluoro-benzene), with an intramolecular Ir?Ir distance of around 6 ? determined crystallographically. Mononuclear analogues [Ir(N^C^N-dpyx)(N^N^O-HLn)]+ have also been isolated. The dinuclear complexes display a well-defined and unusually intense lowest-energy absorption band in the visible region, around 480 nm. They emit much more efficiently than their mononuclear counterparts, even though the emission wavelengths are comparable. Their superior performance appears to be due to an enhancement in the radiative rate constant, affirming conclusions drawn from recent related studies of dinuclear Ir(iii) and Pt(ii) complexes with ditopic, pyrimidine-based cyclometallating ligands.
- Puttock, Emma V.,Sil, Amit,Williams, J. A. Gareth,Yufit, Dmitry S.
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p. 10463 - 10476
(2020/09/18)
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- A family of readily synthesised phosphorescent platinum(ii) complexes based on tridentate: N^N^O -coordinating Schiff-base ligands
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The synthesis and photophysical properties of 22 platinum(ii) complexes featuring N^N^O-coordinating ligands are described. The complexes have the form Pt(N^N^O-Ln)Cl (n = 1 to 20). The tridentate ligands comprise lateral pyridine and phenolate rings, offering the metal N and O coordination respectively, linked via an imine or hydrazone unit that provides a further, central N atom for coordination. The proligands HLn, some of which have previously been reported for the coordination of 1st row transition metal ions in other contexts, are Schiff bases that are readily synthesised by condensation of salicylaldehydes either with 8-aminoquinoline (to generate imine-based ligands HL1-4) or with 2-hydrazinopyridines (to generate hydrazone-based proligands HL5-20). The Pt(ii) complexes are prepared under mild conditions upon treatment of the proligands with simple Pt(ii) salts. Metathesis of the chloride ligand by an acetylide is possible, as exemplified by the preparation of two further complexes of the form Pt(N^N^O-Ln)(-CC-Ar), where Ar = 3,5-bis(trifluoromethyl)phenyl. Nine of the complexes have been characterised in the solid state by X-ray diffraction. The imine-based complexes have intense low-energy absorption bands around 520 nm attributed to charge-transfer transitions. They display deep red phosphorescence in solution at ambient temperature, with λmax in the range 635-735 nm, quantum yields up to 4.6% and lifetimes in the microsecond range. The hydrazone complexes that feature a py-NH-NC-Ar linker display pH-dependent absorption spectra owing to the acidity of the hydrazone NH: these complexes have poor photostability in solution. In contrast, their N-methylated analogues (i.e., py-NMe-NC-Ar) show no evidence of photodecomposition. They are phosphorescent in solution at room temperature in the 600-640 nm region, the emission maximum being influenced by substituents in the phenolate ring. The results show how simply prepared tridentate Schiff base ligands-which offer the metal a combination of 5- and 6-membered chelate rings-can provide access to phosphorescent Pt(ii) complexes that have superior emissive properties to those of terpyridines, for example.
- Puttock, Emma V.,Fradgley, Jack D.,Yufit, Dmitry S.,Gareth Williams
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supporting information
p. 15012 - 15028
(2019/10/22)
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- Electronic absorption and emission properties of bishydrazone [2?×?2] metallosupramolecular grid-type architectures
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Several ditopic ligands containing two tridentate bishydrazone coordination subunits and their Zn(II) and Cd(II) [2 × 2] grid-type complexes were prepared and their photoluminescent properties studied. A special attention was devoted to the influence of the orientation of the hydrazone group N–N[dbnd]in the core of the ligands and their complexes. Its reversal from [pyridine[dbnd]N–N–pyrimidine] (L1) to [pyridine–N–N[dbnd]pyrimidine] (L2) has a strong impact on the observed absorption and emission behaviour of particular ligands (L1 and L2) as well as of their [2 × 2] grid assemblies. The further lateral functionalization of the ligands led to different emission quantum yields of the resulting grids, while their emission and absorption spectra varied very little. The simplest derivative L1 turned out to have the best performance with, for its Zn(II) complex, relatively high quantum yield 60%.
- Holub, Jan,Santoro, Antonio,Lehn, Jean-Marie
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supporting information
p. 223 - 231
(2019/06/07)
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- Nickel-catalyzed direct C-H bond sulfenylation of acylhydrazines
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A Ni-catalyzed direct C-H bond sulfenylation of acylhydrazines was developed. The reaction used N-(pyridinyl)hydrazine as the bidentate-directing group, which can be smoothly removed through reductive N-N cleavage. This system can bear various important functional groups, providing an efficient route for the preparation of diverse diaryl sulfides.
- Li, Jun-Ming,Yu, Yang,Weng, Jiang,Lu, Gui
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supporting information
p. 6047 - 6056
(2018/09/06)
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- The cobalt(II) complex of a new tridentate Schiff-base ligand as a catalyst for hydrosilylation of olefins
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Condensation of 1-methyl-2-imidazolecarboxaldehyde with 2-(1-methylhydrazinyl)pyridine results in the synthesis of new, tridentate Schiff-base ligand L, which readily reacts with CoCl2 to form a monometallic [CoLCl2] complex that, upon reduction, functions as active hydrosilylation catalyst. The ligand and the [CoLCl2] catalyst have been characterized spectroscopically (MS, NMR, FTIR) and by single crystal X-ray diffraction techniques. The results of preliminary catalytic experimentation show that the cobalt complex can induce hydrosilylation and dehydrogenative silylation of olefins, depending upon the hydrosilane substrate used.
- Gorczyński, Adam,Zaranek, MacIej,Witomska, Samanta,Bocian, Aleksandra,Stefankiewicz, Artur R.,Kubicki, MacIej,Patroniak, Violetta,Pawlu?, Piotr
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supporting information
p. 71 - 74
(2016/02/26)
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- Coupled nanomechanical motions: Metal-ion-effected, ph-modulated, simultaneous extension/contraction motions of double-domain helical/linear molecular strands
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A new class of shape-enforced synthetic polyheterocyclic molecular strands, containing both a helical and a linear domain, has been designed and synthesized. On reaction with Pb(II), under the effect of cation binding to the coordination subunits, the helical section unfolds into a linear shape in the complex and the linear domain folds into a helical ligand wrapped around the bound cations. Such double-domain ligand strands are thus able to undergo a combined unfolding-folding interconversion on binding and release of metal cations. These changes can be modulated through coupling to a competing ligand that reversibly binds and releases metal cations, when respectively unprotonated and protonated, on effecting alternate pH changes. The resulting process thus performs nanomechanical extension/contraction molecular motions of a linear motor type, which is fueled by acid-base neutralization.
- Stadler, Adrian-Mihail,Lehn, Jean-Marie P.
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supporting information
p. 3400 - 3409
(2014/03/21)
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- HYDRAZIDE CONTAINING NUCLEAR TRANSPORT MODULATORS AND USES THEREOF
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The invention generally relates to nuclear transport modulators, e.g., CRM1 inhibitors, and more particularly to a compound represented by structural formula (I): or a pharmaceutically acceptable salt thereof, wherein the values and alternative values for the variables are as defined and described herein. The invention also includes the synthesis and use of a compound of structural formula I, or a pharmaceutically acceptable salt or composition thereof, e.g., in the treatment, modulation and/or prevention of physiological conditions associated with CRM1 activity.
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Page/Page column 60
(2013/03/26)
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- Rapid determination of enantiomeric excess of α-chiral cyclohexanones using circular dichroism spectroscopy
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Chemical equations presented. Ketone handedness was discriminated using circular dichroism (CD) spectroscopy by monitoring the metal-to-ligand charge transfer (MLCT) bands of complexes between [CuI((S)-1)(CH 3CN)2]PF6 and derivatized α-chiral cyclohexanones (4). This method was able to quantify the enantiomeric excess of unknown samples using a calibration curve, giving an absolute error of ±7%. The analysis was fast, allowing potential application of this assay in high-throughput screening (HTS).
- Leung, Diana,Anslyn, Eric V.
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supporting information; experimental part
p. 2298 - 2301
(2011/06/26)
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- INHIBITORS OF FLAVIVIRIDAE VIRUSES
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Provided are compounds of Formula I: and pharmaceutically acceptable salts and esters thereof. The compounds, compositions, and methods provided are useful for the treatment of Flaviviridae virus infections, particularly hepatitis C infections.
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Page/Page column 52-53
(2011/08/04)
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- Discovery of ectoparasiticidal hydrazonotrifluoromethanesulfonanilides
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A series of hydrazonotrifluorosulfonanilide derivatives were synthesized and evaluated for in vitro activity against the ectoparasites Ctenocephalides felis and Rhipicephalus sanguineus. Some compounds with excellent activity against tick were identified.
- Ali, Abdelselam,Fisara, Petr,Freemont, Jamie A.,Kyi, Stella,Meyer, Adam G.,Riches, Andrew G.,Sargent, Roger M.,Sawutz, David G.,Turner, Kathleen A.,Winzenberg, Kevin N.,Yang, Qi
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scheme or table
p. 649 - 652
(2010/06/12)
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- N-PHENYL-1,1,1-TRIFLUOROMETHANESULFONAMIDE HYDRAZONE DERIVATIVE COMPOUNDS AND THEIR USAGE IN CONTROLLING PARASITES
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Novel N-phenyl-1,1,1-trifluoromethanesulfonamide compounds useful for controlling endo and/or ectoparasites in the environment are provided, together with methods of making the same, and methods of using the inventive compounds to treat parasite infestations in vivo and ex vivo.
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Page/Page column 38
(2008/06/13)
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- Red colouring photochromic 6′-substituted spiroindolinonaphth[2,1-b][1,4]oxazines
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Electron donating/withdrawing substituents and electronegative centres have been successfully employed in substantially widening the range of photo-generated colours available in the spiroindolinonaphthoxazine class of photochromic materials.
- Rickwood,Marsden,Ormsby,Staunton,Wood,Hepworth,Gabbutt
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- Synthesis of 2,6-Diformyl-3-hydroxypyridine Bis: A Pentadentate N,N,N,N,N Ligand for the Preparation of Chelating Resins
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The synthesis of 2,6-diformyl-3-hydroxypyridine bis as a versatile intermediate with a reactive hydroxyl group, which can be bonded to lipophilic chains and/or to polymeric supports, is reported.
- Baldo, Maria Antonietta,Chessa, Gavino,Marangoni, Giampaolo,Pitteri, Bruno
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p. 720 - 723
(2007/10/02)
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- (Nitrofuryl)pyrazoles, their synthesis and use, and compositions containing them
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3-(5-Nitro-2-furyl)pyrazoles unsubstituted in the 5-position and 5-(5-nitro-2-furyl)pyrazoles unsubstituted in the 3-position are antimicrobials and disinfectants. The compounds are structurally represented by one of the formulae: STR1 wherein A is --CHO, --CN, --COOH, a protected or derived aldehyde group or a protected or derived carboxylic acid group; B is 5-nitro-2-furyl; R1 is --H, substituted or unsubstituted hydrocarbyl (saturated or unsaturated; acyclic, alicyclic or aromatic; or araliphatic); substituted or unsubstituted (cycloaliphatic or aromatic) heterocyclic or acyl (carboxylic or carbonic acid); R2 is --H; and n is a positive whole number of at most 2.
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