336 research outputs found

    (R)-(1-Ammonio­prop­yl)phospho­nate

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    The title compound, C3H10NO3P, crystallizes in its zwitterionic form, H3N+CH(C2H5)PO(O−)(OH), with the asymmetric unit being composed by two of such entities (Z′ = 2). The crystal packing leads to a sequence of hydro­phobic and hydro­philic layers. While the hydro­phobic layer comprises the aliphatic substituent groups, the hydro­philic one is held together by a series of strong and rather directional N+—H⋯O and O—H⋯O hydrogen bonds

    Synthesis of 3-indolylazoles and meridianin derivatives from indolyl enaminonitriles

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    The reaction of indole derivatives with cyanoacetic acid followed by treatment with DMFDMA gave the intermediate indolyl enaminonitriles (3). Further reaction with aminoguanidine yielded 5´-cyanomeridianin analogues (4). The same intermediate reacted with p-methoxyphenylhydrazine to give the pyrazolyl derivative (8). Treatment of (2E)-3-dimethylamino-2-(1H-indol-3-yl)-propenoate (3a) with hydroxylamine hydrochloride in basic medium afforded (5-amino-isoxazol-4-yl)-(1H-indol-3-yl)-methanone (5) and the acrylic acid derivative (6) after a short or a long heating, respectively. Unequivocal structural elucidation of the latter compound was achieved from single-crystal X-ray diffraction studies.Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BPD/31490/2006FEDER - REEQ/ 630/QUI/200

    Glycine methyl ester hydro­chloride

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    The title compound [systematic name: (methoxy­carbonyl­meth­yl)ammonium chloride], crystallizes as a salt, C3H8NO2 +·Cl−, with the charged species inter­acting mutually via strong and highly directional N+—H⋯Cl− hydrogen bonds which lead to the formation of a supra­molecular tape running parallel to the c axis. Tapes close pack in the solid state mediated by multipoint recognition synthons based on weak C—H⋯O inter­actions and van der Waals contacts between adjacent methyl groups

    Interconvertable modular framework and layered lanthanide(III)-etidronic acid coordination polymers

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    POCI/QUI/58377/2004 - FEDERSFRH/BPD/9309/2002 (to F.-N.S.)SFRH/BPD/14410/2003 (to L.C.-S.)NoE FAM

    Methyl 2-(4,6-dichloro-1,3,5-triazin-2-yl­amino)acetate

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    The title compound, C6H6Cl2N4O2, was prepared by the nucleophilic substitution of 2,4,6-trichloro-1,3,5-triazine by glycine methyl ester hydro­chloride, and was isolated from the reaction by using flash chromatography. The crystal structure at 150 K reveals the presence two crystallographically independent mol­ecules in the asymmetric unit which differ in the orientation of the pendant methoxy­carbonyl group. Each mol­ecular unit is engaged in strong and highly directional N—H⋯N hydrogen-bonding inter­actions with a symmetry-related mol­ecule, forming supra­molecular dimers which act as the synthons in the crystal packing

    Octatosylaminophthalocyanine: a reusable chromogenic anion chemosensor

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    Detailed herein is the use of 2,3,9,10,16,17,23,24-octatosylaminophthalocyanine as a chromogenic chemosensor for anions. The host:guest complexes formed during the sensing event can be regenerated by acid treatment without loss of the sensing ability. This allows the phthalocyanine chemosensor to be reused. This system also responds in a colorimetric manner when exposed to the neutral solvent molecules, dimethyl sulfoxide and methanol. A single-crystal X-ray structure of the Pc 1:2 MeOH complex was obtained. It illustrates the main interactions between the host:guest species in the solid state. Fits of the binding curves are consistent with this stoichiometry predominating in the solution state

    Unexplored outflows in nearby low luminosity AGNs: the case of NGC 1052

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    Outflows play a central role in galaxy evolution shaping the properties of galaxies. Understanding outflows and their effects in low luminosity AGNs, such as LINERs, is essential (e.g. they are a numerous AGN population in the local Universe). We obtained VLT/MUSE and GTC/MEGARA optical IFS-data for NGC1052, the prototypical LINER. The stars are distributed in a dynamically hot disc, with a centrally peaked velocity dispersion map and large observed velocity amplitudes. The ionised gas, probed by the primary component is detected up to \sim30arcsec (\sim3.3 kpc) mostly in the polar direction with blue and red velocities (\midV\mid<<250 km/s). The velocity dispersion map shows a notable enhancement (σ\sigma>>90 km/s) crossing the galaxy along the major axis of rotation in the central 10arcsec. The secondary component has a bipolar morphology, velocity dispersion larger than 150 km/s and velocities up to 660 km/s. A third component is detected but not spatially resolved. The maps of the NaD absorption indicate optically thick neutral gas with a velocity field consistent with a slow rotating disc (Δ\DeltaV = 77±\pm12 km/s) but the velocity dispersion map is off-centred without any counterpart in the flux map. We found evidence of an ionised gas outflow with mass of 1.6±\pm0.6 ×\times 105^{5} Msun, and mass rate of 0.4±\pm0.2 Msun/yr. The outflow is propagating in a cocoon of gas with enhanced turbulence and might be triggering the onset of kpc-scale buoyant bubbles (polar emission). Taking into account the energy and kinetic power of the outflow (1.3±\pm0.9 ×\times 1053^{53} erg and 8.8±\pm3.5 ×\times 1040^{40} erg/s, respectively) as well as its alignment with both the jet and the cocoon, and that the gas is collisionally ionised, we consider that the outflow is jet-powered, although some contribution from the AGN is possible.Comment: A&A accepted 04/04/2022, 31 pages, 12 figures and 3 appendixe

    Molybdenum(VI) complexes with ligands derived from 5-(2-pyridyl)-2H-tetrazole as catalysts for the epoxidation of olefins

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    The development of effective catalytic epoxidation processes that are an alternative to stoichiometric non-selective oxidation routes is important to meet environmental sustainability goals. In this work, molybdenum (VI) compounds bearing 5-(2-pyridyl)-2H-tetrazole derivatives as organic components, namely the ionic and neutral mononuclear complexes (H2ptz)[MoO2Cl2(ptz)] (1) and [MoO2Cl2(tBu-ptz)] (2), and the new Lindqvist-type polyoxometalate (POM) [tBu-Hptz]2[Mo6O19] (3), where Hptz = 5-(2-pyridyl)tetrazole and tBu-ptz = 2-tert- butyl-5-(2-pyridyl)- 2H-tetrazole, were studied as epoxidation catalysts using readily available and relatively ecofriendly hydroperoxide oxidants, namely hydrogen peroxide and tert-butyl hydroperoxide (TBHP). The pre-pared catalysts were very active. For example, 100% cis-cyclooctene conversion and 100% epoxide selectivity were reached at 1 h for 1 and 3, and 10 min for 2 (with TBHP). Catalytic and characterization studies indicated that the mononuclear complexes suffered chemical transformations under the reaction conditions, whereas 3 was structurally stable. This POM acted as a homogeneous catalyst and could be recycled by employing an ionic liquid solvent. The POM can be synthesized from 2 under different conditions, including those used in the catalytic process. Moreover, 3 was an effective epoxidation catalyst for a biobased substrate scope that included fatty acid methyl esters and the terpene dl-limonene.POCI-01-0145-FEDER-030075; LA/P/0006/2020; EMBRC.PT ALG-01–0145-FEDER-022121; (grant ref. 2021.06403.BDinfo:eu-repo/semantics/publishedVersio

    Thermal and structural analysis of 4,5,6-trimethoxyisatin

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    4,5,6-Trimethoxyisatin was crystallized from water to give dark red needles that were characterized by NMR and IR spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), single-crystal X-ray diffraction (XRD) and hot-stage microscopy.Fundação para a Ciência e a Tecnologia (FCT) - POCTISFA-3-686Fundo Europeu de Desenvolvimento Regional (FEDER

    Lanthanide-based complexes as efficient physiological temperature sensors

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    A new molecular thermometric sensor based on the terbium(III) complex [C2mim][Tb(fod)4] (C2mim – 1-methyl-3-ethylimidazolium, fod− - tetrakis-6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionate), doped with 0.015% of its europium(III) analogue (1, [C2mim][Tb(fod)4]0.99985:[C2mim][Eu(fod)4]0.00015), was prepared and its thermochromic behaviour evaluated from ambient temperature up to 75 °C, including in the physiological range (35–45 °C). It was found that the intensity ratio of the 5D4→7F5 (TbIII) and 5D0→7F2 (EuIII) transitions is correlated with temperature having three different linear regimes. Visual colorimetry allowed the evaluation of the temperature in different ranges from green at ambient temperature, to yellow and finally red at higher temperatures. The TbIII complex emission intensity is extremely sensitive to small temperature variations, particularly between 25 and 35 °C, were it reaches only 40% of the initial intensity. Confinement of the dopped TbIII tetrakis-complex in the organic polymeric matrix poly(methylmethacrylate) (PMMA) induced higher thermal stability in 1, together with a strong temperature dependence of the most intense emissive transition of the TbIII complexes. The photoluminescence quantum yield of polymer-lanthanide hybrid materials increased significantly compared with that of 1. Under 366 nm irradiation, the hybrid material presents a green colour at 25 °C that evolves to yellow at 30 °C and to a white tone at 35 °C.publishe
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