336 research outputs found
(R)-(1-Ammoniopropyl)phosphonate
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
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
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
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
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
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
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
30arcsec (3.3 kpc) mostly in the polar direction with blue and red
velocities (V250 km/s). The velocity dispersion map shows a
notable enhancement (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 (V = 7712 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 1.60.6
10 Msun, and mass rate of 0.40.2 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 (1.30.9 10 erg and
8.83.5 10 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
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
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
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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