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1.
Proc Natl Acad Sci U S A ; 116(26): 12907-12912, 2019 06 25.
Artículo en Inglés | MEDLINE | ID: mdl-31186360

RESUMEN

While the physical dimensions of climate change are now routinely assessed through multimodel intercomparisons, projected impacts on the global ocean ecosystem generally rely on individual models with a specific set of assumptions. To address these single-model limitations, we present standardized ensemble projections from six global marine ecosystem models forced with two Earth system models and four emission scenarios with and without fishing. We derive average biomass trends and associated uncertainties across the marine food web. Without fishing, mean global animal biomass decreased by 5% (±4% SD) under low emissions and 17% (±11% SD) under high emissions by 2100, with an average 5% decline for every 1 °C of warming. Projected biomass declines were primarily driven by increasing temperature and decreasing primary production, and were more pronounced at higher trophic levels, a process known as trophic amplification. Fishing did not substantially alter the effects of climate change. Considerable regional variation featured strong biomass increases at high latitudes and decreases at middle to low latitudes, with good model agreement on the direction of change but variable magnitude. Uncertainties due to variations in marine ecosystem and Earth system models were similar. Ensemble projections performed well compared with empirical data, emphasizing the benefits of multimodel inference to project future outcomes. Our results indicate that global ocean animal biomass consistently declines with climate change, and that these impacts are amplified at higher trophic levels. Next steps for model development include dynamic scenarios of fishing, cumulative human impacts, and the effects of management measures on future ocean biomass trends.


Asunto(s)
Biomasa , Cambio Climático , Océanos y Mares , Animales , Organismos Acuáticos/fisiología , Explotaciones Pesqueras/estadística & datos numéricos , Peces/fisiología , Cadena Alimentaria , Modelos Teóricos
2.
Glob Chang Biol ; 27(21): 5514-5531, 2021 11.
Artículo en Inglés | MEDLINE | ID: mdl-34486773

RESUMEN

Marine spatial planning that addresses ocean climate-driven change ('climate-smart MSP') is a global aspiration to support economic growth, food security and ecosystem sustainability. Ocean climate change ('CC') modelling may become a key decision-support tool for MSP, but traditional modelling analysis and communication challenges prevent their broad uptake. We employed MSP-specific ocean climate modelling analyses to inform a real-life MSP process; addressing how nature conservation and fisheries could be adapted to CC. We found that the currently planned distribution of these activities may become unsustainable during the policy's implementation due to CC, leading to a shortfall in its sustainability and blue growth targets. Significant, climate-driven ecosystem-level shifts in ocean components underpinning designated sites and fishing activity were estimated, reflecting different magnitudes of shifts in benthic versus pelagic, and inshore versus offshore habitats. Supporting adaptation, we then identified: CC refugia (areas where the ecosystem remains within the boundaries of its present state); CC hotspots (where climate drives the ecosystem towards a new state, inconsistent with each sectors' present use distribution); and for the first time, identified bright spots (areas where oceanographic processes drive range expansion opportunities that may support sustainable growth in the medium term). We thus create the means to: identify where sector-relevant ecosystem change is attributable to CC; incorporate resilient delivery of conservation and sustainable ecosystem management aims into MSP; and to harness opportunities for blue growth where they exist. Capturing CC bright spots alongside refugia within protected areas may present important opportunities to meet sustainability targets while helping support the fishing sector in a changing climate. By capitalizing on the natural distribution of climate resilience within ocean ecosystems, such climate-adaptive spatial management strategies could be seen as nature-based solutions to limit the impact of CC on ocean ecosystems and dependent blue economy sectors, paving the way for climate-smart MSP.


Asunto(s)
Cambio Climático , Ecosistema , Adaptación Fisiológica , Conservación de los Recursos Naturales , Explotaciones Pesqueras , Oceanografía
3.
Glob Chang Biol ; 26(7): 3891-3905, 2020 07.
Artículo en Inglés | MEDLINE | ID: mdl-32378286

RESUMEN

Large-scale and long-term changes in fish abundance and distribution in response to climate change have been simulated using both statistical and process-based models. However, national and regional fisheries management requires also shorter term projections on smaller spatial scales, and these need to be validated against fisheries data. A 26-year time series of fish surveys with high spatial resolution in the North-East Atlantic provides a unique opportunity to assess the ability of models to correctly simulate the changes in fish distribution and abundance that occurred in response to climate variability and change. We use a dynamic bioclimate envelope model forced by physical-biogeochemical output from eight ocean models to simulate changes in fish abundance and distribution at scales down to a spatial resolution of 0.5°. When comparing with these simulations with annual fish survey data, we found the largest differences at the 0.5° scale. Differences between fishery model runs driven by different biogeochemical models decrease dramatically when results are aggregated to larger scales (e.g. the whole North Sea), to total catches rather than individual species or when the ensemble mean instead of individual simulations are used. Recent improvements in the fidelity of biogeochemical models translate into lower error rates in the fisheries simulations. However, predictions based on different biogeochemical models are often more similar to each other than they are to the survey data, except for some pelagic species. We conclude that model results can be used to guide fisheries management at larger spatial scales, but more caution is needed at smaller scales.


Asunto(s)
Explotaciones Pesqueras , Peces , Animales , Cambio Climático , Ecosistema , Mar del Norte
4.
Chemistry ; 24(50): 13170-13180, 2018 Sep 06.
Artículo en Inglés | MEDLINE | ID: mdl-30028544

RESUMEN

The metal-organic frameworks (MOFs) M(BPZNO2 ) (M=Co, Cu, Zn; H2 BPZNO2 =3-nitro-4,4'-bipyrazole) were prepared through solvothermal routes and were fully investigated in the solid state. They showed good thermal stability both under a N2 atmosphere and in air, with decomposition temperatures peaking up to 663 K for Zn(BPZNO2 ). Their crystal structure is characterized by 3D networks with square (M=Co, Zn) or rhombic (M=Cu) channels decorated by polar NO2 groups. As revealed by N2 adsorption at 77 K, they are micro-mesoporous materials with BET specific surface areas ranging from 400 to 900 m2 g-1 . Remarkably, under the mild conditions of 298 K and 1.2 bar, Zn(BPZNO2 ) adsorbs 21.8 wt % CO2 (4.95 mmol g-1 ). It shows a Henry CO2 /N2 selectivity of 15 and an ideal adsorbed solution theory (IAST) selectivity of 12 at p=1 bar. As a CO2 adsorbent, this compound is the best-performing MOF to date among those bearing a nitro group as a unique chemical tag. High-resolution powder X-ray diffraction at 298 K and different CO2 loadings revealed, for the first time in a NO2 -functionalized MOF, the insurgence of primary host-guest interactions involving the C(3)-NO2 moiety of the framework and the oxygen atoms of carbon dioxide, as confirmed by Grand Canonical Monte Carlo simulations. This interaction mode is markedly different from that observed in NH2 -functionalized MOFs, for which the carbon atom of CO2 is involved.

5.
Glob Chang Biol ; 22(12): 3927-3936, 2016 12.
Artículo en Inglés | MEDLINE | ID: mdl-27396719

RESUMEN

The Paris Conference of Parties (COP21) agreement renewed momentum for action against climate change, creating the space for solutions for conservation of the ocean addressing two of its largest threats: climate change and ocean acidification (CCOA). Recent arguments that ocean policies disregard a mature conservation research field and that protected areas cannot address climate change may be oversimplistic at this time when dynamic solutions for the management of changing oceans are needed. We propose a novel approach, based on spatial meta-analysis of climate impact models, to improve the positioning of marine protected areas to limit CCOA impacts. We do this by estimating the vulnerability of ocean ecosystems to CCOA in a spatially explicit manner and then co-mapping human activities such as the placement of renewable energy developments and the distribution of marine protected areas. We test this approach in the NE Atlantic considering also how CCOA impacts the base of the food web which supports protected species, an aspect often neglected in conservation studies. We found that, in this case, current regional conservation plans protect areas with low ecosystem-level vulnerability to CCOA, but disregard how species may redistribute to new, suitable and productive habitats. Under current plans, these areas remain open to commercial extraction and other uses. Here, and worldwide, ocean conservation strategies under CCOA must recognize the long-term importance of these habitat refuges, and studies such as this one are needed to identify them. Protecting these areas creates adaptive, climate-ready and ecosystem-level policy options for conservation, suitable for changing oceans.


Asunto(s)
Cambio Climático , Conservación de los Recursos Naturales , Ecosistema , Océanos y Mares , Cadena Alimentaria , Actividades Humanas , Humanos
6.
Glob Chang Biol ; 21(1): 130-43, 2015 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-25044416

RESUMEN

Understanding long-term, ecosystem-level impacts of climate change is challenging because experimental research frequently focuses on short-term, individual-level impacts in isolation. We address this shortcoming first through an interdisciplinary ensemble of novel experimental techniques to investigate the impacts of 14-month exposure to ocean acidification and warming (OAW) on the physiology, activity, predatory behaviour and susceptibility to predation of an important marine gastropod (Nucella lapillus). We simultaneously estimated the potential impacts of these global drivers on N. lapillus population dynamics and dispersal parameters. We then used these data to parameterize a dynamic bioclimatic envelope model, to investigate the consequences of OAW on the distribution of the species in the wider NE Atlantic region by 2100. The model accounts also for changes in the distribution of resources, suitable habitat and environment simulated by finely resolved biogeochemical models, under three IPCC global emissions scenarios. The experiments showed that temperature had the greatest impact on individual-level responses, while acidification had a similarly important role in the mediation of predatory behaviour and susceptibility to predators. Changes in Nucella predatory behaviour appeared to serve as a strategy to mitigate individual-level impacts of acidification, but the development of this response may be limited in the presence of predators. The model projected significant large-scale changes in the distribution of Nucella by the year 2100 that were exacerbated by rising greenhouse gas emissions. These changes were spatially heterogeneous, as the degree of impact of OAW on the combination of responses considered by the model varied depending on local-environmental conditions and resource availability. Such changes in macro-scale distributions cannot be predicted by investigating individual-level impacts in isolation, or by considering climate stressors separately. Scaling up the results of experimental climate change research requires approaches that account for long-term, multiscale responses to multiple stressors, in an ecosystem context.


Asunto(s)
Ecosistema , Gastrópodos/fisiología , Calor , Concentración de Iones de Hidrógeno , Dinámica Poblacional , Conducta Predatoria/fisiología , Agua de Mar/química , Distribución Animal/fisiología , Animales , Océano Atlántico , Calentamiento Global , Modelos Teóricos
7.
Molecules ; 20(7): 12341-63, 2015 Jul 07.
Artículo en Inglés | MEDLINE | ID: mdl-26198221

RESUMEN

The synthesis and structural characterization of five transition metal complexes with different dimensionality and incorporating residues of 3-amino-1H-1,2,4-triazole-5-carboxylic acid (H2atrc) is reported: [Zn(Hatrc)2(H2O)] (1), [Mn(Hatrc)2(H2O)2]·2H2O (2), [Fe2(Hatrc)4(OH)2]·6H2O (3), [Cd(Hatrc)2(H2O)]n (4), and [Mn(atrc)(H2O)]n·nH2O (5). These materials could be prepared from solution (1-3), diffusion (4), or hydrothermal reactions (5) with various anions and L:M ratios. Structural details were revealed by single crystal X-ray diffraction. The discrete units composing compounds 1-3, the polymeric 1D chain of 4 and the 2D layer of 5 are further extended into 3D supramolecular architectures through the formation of hydrogen bonds.


Asunto(s)
Ácidos Carboxílicos/química , Metales Pesados/química , Triazoles/química , Ligandos , Modelos Moleculares , Polímeros/química
8.
Bioorg Med Chem ; 22(11): 3008-15, 2014 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-24775915

RESUMEN

Synthesis of the bis-4-hydroxycoumarin-type compound, 3,3'-[3-(2-hydroxyphenyl)-3-oxopropane-1,1-diyl]bis(4-hydroxy-2H-chromen-2-one), was performed by two alternative pathways, either involving a basic organocatalyzed 1,4-conjugate addition tandem reaction of 4-hydroxycoumarin on chromone-3-carboxylic acid, or a double condensation of 4-hydroxycoumarin on ω-formyl-2'-hydroxyacetophenone. The anti-proliferative effects of the bis-4-hydroxycoumarin-type compound on human K-562 (chronic myeloid leukaemia) and JURKAT (acute T-cell leukaemia) cell lines using trypan blue staining, as well as its involvement in nuclear factor-kappa B (NF-κB) regulation analyzed by luciferase reporter gene assay, gene expression analysis and western blots were analysed. This compound inhibited TNFα-induced NF-κB activation in K-562 (IC50 17.5 µM) and JURKAT (IC50 19.0 µM) cell lines, after 8h of incubation. Interestingly, it exerted mainly cytostatic effects at low doses on both cell lines tested, whereas it decreased JURKAT cell viability starting at 50 µM from 24h of treatment. Importantly, it did not affect the viability of peripheral blood mononuclear cells (PBMCs) from healthy donors, even at concentrations above 100 µM.


Asunto(s)
Antineoplásicos/farmacología , Cromonas/farmacología , FN-kappa B/antagonistas & inhibidores , Antineoplásicos/síntesis química , Antineoplásicos/química , Ciclo Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Cromonas/síntesis química , Cromonas/química , Relación Dosis-Respuesta a Droga , Ensayos de Selección de Medicamentos Antitumorales , Humanos , Células K562 , Modelos Moleculares , Estructura Molecular , FN-kappa B/metabolismo , Relación Estructura-Actividad , Células Tumorales Cultivadas
9.
Acta Crystallogr Sect E Struct Rep Online ; 70(Pt 2): o126, 2014 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-24764854

RESUMEN

The asymmetric unit of the title compound, C18H17N3O, consists of two independent mol-ecules, each having an E conformation with respect to the C=C bond between the benzodiazepinone and di-methyl-amine groups. In the crystal, the two independent mol-ecules are linked into a dimer by a pair of N-H⋯O hydrogen bonds.

10.
Neotrop Entomol ; 53(1): 175-179, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-38032477

RESUMEN

This is the first report of Antiteuchus tripterus (Fabricius, 1787) (Heteroptera: Pentatomidae) damaging Araucaria angustifolia (Bertol.) Kuntze, 1898 (Pinales: Araucariaceae) plants in Brazil. This bug, native to the neotropical region, damaged this plant on fragments of mixed rain forest in Bueno Brandão, Minas Gerais state, Brazil. Araucaria angustifolia, native and with ecological and economic values, was widely used in the lumber market and, therefore, threatened with extinction. Nymphs and adults of A. tripterus were observed in March and April with a population reduction until June 2022. The bioecology and damage caused by A. tripterus on A. angustifolia are not known.


Asunto(s)
Araucaria , Heterópteros , Animales , Brasil , Ninfa , Dinámica Poblacional
11.
Cureus ; 15(1): e34422, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-36874655

RESUMEN

IgA vasculitis is a small vessel vasculitis mediated by the deposition of IgA immune complexes. It mostly occurs in children and is rare in adults, with increased severity and mortality in the latter. Its aetiology remains largely unknown, and its prognosis depends primarily on the extent of renal involvement. We present the case of a 71-year-old woman with purpuric lesions in both lower and upper limbs associated with fever, abdominal pain, vomiting and blood in her stools for the past month. The patient was diagnosed with IgA vasculitis and the full systemic involvement (renal, dermatological, intestinal, and cerebral) of the disease was identified with excellent response to parenteral corticotherapy.

12.
Environ Sci Technol ; 46(15): 8220-8, 2012 Aug 07.
Artículo en Inglés | MEDLINE | ID: mdl-22758786

RESUMEN

This paper describes the development of the EU Water Framework Directive central water quality elements from 1970 to 2010 in the Gulf of Finland, a eutrophied sub-basin of the Baltic Sea. The likelihood of accomplishing the management objectives simultaneously is assessed using Bayesian networks. The objectives of good ecological status in winter-time total nitrogen and phosphorus, summer-time chlorophyll-a and summer-time Secchi depth have not been met yet. In addition, the results indicate that it is unlikely for them to be achieved in the near future, despite the decreasing trend in nutrient concentrations over the past few years. It was demonstrated that neither phosphorus nor nitrogen alone controls summertime plankton growth. Reaching good ecological status in nutrients does not necessarily lead to good ecological status of chlorophyll-a, even though a dependency between the parameters does exist. In addition, secchi-depth status is strongly related to chlorophyll-a status in three of the four study-areas.


Asunto(s)
Calidad del Agua , Teorema de Bayes , Finlandia , Funciones de Verosimilitud , Nitrógeno/análisis , Fósforo/análisis , Agua de Mar
13.
Acta Crystallogr C ; 68(Pt 3): o104-7, 2012 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-22382541

RESUMEN

The title compound, C(48)H(20)F(19)N(4)O(3)P, prepared by the nucleophilic attack of triethyl phosphite on one of the 4-fluoro atoms of 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin, contains a single molecule in the asymmetric unit. The porphyrin unit is almost planar [largest non-H atom deviation = 0.174 (6) Å], and has the planes of the neighbouring benzene rings oriented at angles ranging from 64.3 (2) to 89.6 (3)° relative to the porphyrin core. The P=O group is almost coplanar with the attached benzene ring, subtending an angle of 4.0 (3)°. Several weak supramolecular interactions, namely C-H...π, C-F...π, P=O...π, C-H...(O,F) and F...F contacts, contribute to the crystal packing.

14.
Acta Crystallogr Sect E Struct Rep Online ; 68(Pt 3): m294-5, 2012 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-22412438

RESUMEN

The asymmetric unit of the title compound, poly[(µ(4)-{[bis-(hydrogen phospho-natometh-yl)aza-nium-yl]meth-yl}phospho-nato)lanthanum(III)], [La(C(3)H(9)NO(9)P(3))](n), comprises an La(3+) center and a H(3)nmp(3-) anion (where H(3)nmp(3-) is a residue of partially deprotonated nitrilo-tris-(methyl-ene-phospho-nic acid), namely {[bis-(hydrogen phospho-natometh-yl)aza-nium-yl]meth-yl}-phos-pho-nate). This study concerns a structural redetermination using single-crystal X-ray diffraction data, collected at the low temperature of 180 K, of a recently investigated material whose structural details have been proposed from powder X-ray diffraction studies [Silva et al. (2011 ▶). J. Am. Chem. Soc.133, 15120-15138]. The main difference between the two models rests on the position of the H atoms. While two H atoms were modeled as attached to the same phospho-nate group in the powder determination, in the current model, the same H atoms are instead distributed among two of these groups. The sample studied was an inversion twin.

15.
Acta Crystallogr Sect E Struct Rep Online ; 68(Pt 11): o3143, 2012 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-23284464

RESUMEN

The title compound, C(23)H(19)N, was obtained unexpectedly from the reaction of [Eu(nta)(3)(PzPy)] {Hnta = 1-(2-naphtho-yl)-3,3,3-trifluoro-acetone and PzPy = 2-[3(5)-pyrazol-yl]pyridine} with 1-naphthyl-methyl-amine. The 1- and 2-naphthyl groups are essentially planar [r.m.s. deviations of 0.007 and 0.011 Å, respectively] and subtend angles of 38.69 (11) and 16.50 (11)°, respectively, with the central CH(3)-C=N-CH(2) unit, which is also almost planar [r.m.s. deviation = 0.002 Å]. In the crystal, the mol-ecules are disposed in zigzag-type fashion, forming layers perpendicular to [100]. Weak supra-molecular C-H⋯π inter-actions contribute to the packing forces.

16.
Acta Crystallogr Sect E Struct Rep Online ; 68(Pt 11): o3233-4, 2012 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-23284534

RESUMEN

The title compound, C(15)H(22)N(2)O(3), was obtained as a by-product of oxidative cleavage of 1,3-dicyclo-hexyl-(3-oxo-2,3-dihydro-benzofuran-2-yl)imidazolidine-2,4-dione. Herein, we report the crystal structure of a second polymorph, which was obtained by crystallization from an ethanol solution at 253 K, instead of slow evaporation of the same solvent at room temperature. While the first polymorph [Talhi et al. (2011). Acta Cryst. E67, o3243] crystallized in the non-centrosymmetric space group P2(1)2(1)2(1), this second polymorph crystallizes in the centrosymmetric space group P2(1)/n. Compared to the first polymorph, in the crystal no C=O⋯C=O inter-actions were found (C⋯O inter-molecular distance longer than 3.15 Å) and instead, close packing of individual mol-ecular units is mediated by C-H⋯π and weak C-H⋯O inter-actions.

17.
J Fungi (Basel) ; 8(9)2022 Aug 23.
Artículo en Inglés | MEDLINE | ID: mdl-36135617

RESUMEN

The genus Acaulospora has undergone many updates since it was first described; however, there are some missing pieces in the phylogenetic relationships among Acaulospora species. The present review aimed to: (i) understand the evolutionary meaning of their different spore wall ornamentations; (ii) define the best molecular marker for phylogenetic inferences, (iii) address some specific issues concerning the polyphyletic nature of Acaulospora lacunosa and Acaulospora scrobiculata, and the inclusion of Kuklospora species; and (iv) update the global geographical distribution of Acaulospora species. As such, the wall ornamentation of previously described Acaulospora species was reviewed and phylogenetic analyses were carried out based on ITS and SSU-ITS-LSU (nrDNA). Moreover, the already available type material of A. sporocarpia was inspected. According to the data obtained, temperate and tropical zones are the richest in Acaulospora species. We also confirmed that A. sporocarpia does not belong to Acaulospora. Furthermore, our phylogeny supported the monophyly of Acaulospora genus, including the Kuklospora species, K. colombiana and K. kentinensis. The nrDNA phylogeny presented the best resolution and revealed the homoplasic nature of many ornamentations in Acaulospora species, pointing out their unfeasible phylogenetic signal. This review reinforces the urgency of more molecular markers, in addition to the nrDNA sequences, for the definition of a multi-locus phylogeny.

18.
J Am Chem Soc ; 133(38): 15120-38, 2011 Sep 28.
Artículo en Inglés | MEDLINE | ID: mdl-21815620

RESUMEN

The preparation of layered [La(H(3)nmp)] as microcrystalline powders from optimized microwave-assisted synthesis or dynamic hydrothermal synthesis (i.e., with constant rotation of the autoclaves) from the reaction of nitrilotris(methylenephosphonic acid) (H(6)nmp) with LaCl(3)·7H(2)O is reported. Thermogravimetry in conjunction with thermodiffractometry showed that the material undergoes a microcrystal-to-microcrystal phase transformation above 300 °C, being transformed into either a three-dimensional or a two-dimensional network (two models are proposed based on dislocation of molecular units) formulated as [La(L)] (where L(3-) = [-(PO(3)CH(2))(2)(NH)(CH(2)PO(2))O(1/2)-](n)(3n-)). The two crystal structures were solved from ab initio methods based on powder X-ray diffraction data in conjunction with structural information derived from (13)C and (31)P solid-state NMR, electron microscopy (SEM and EDS mapping), FT-IR spectroscopy, thermodiffractometry, and photoluminescence studies. It is shown that upon heating the coordinated H(3)nmp(3-) anionic organic ligand undergoes a polymerization (condensation) reaction to form in situ a novel and unprecedented one-dimensional polymeric organic ligand. The lanthanum oxide layers act, thus, simultaneously as insulating and templating two-dimensional scaffolds. A rationalization of the various steps involved in these transformations is provided for the two models. Photoluminescent materials, isotypical with both the as-prepared ([(La(0.95)Eu(0.05))(H(3)nmp)] and [(La(0.95)Tb(0.05))(H(3)nmp)]) and the calcined ([(La(0.95)Eu(0.05))(L)]) compounds and containing stoichiometric amounts of optically active lanthanide centers, have been prepared and their photoluminescent properties studied in detail. The lifetimes of Eu(3+) vary between 2.04 ± 0.01 and 2.31 ± 0.01 ms (considering both ambient and low-temperature studies). [La(H(3)nmp)] is shown to be an effective heterogeneous catalyst in the ring opening of styrene oxide with methanol or ethanol, producing 2-methoxy-2-phenylethanol or 2-ethoxy-2-phenylethanol, respectively, in quantitative yields in the temperature range 40-70 °C. The material exhibits excellent regioselectivity to the ß-alkoxy alcohol products even in the presence of water. Catalyst recycling and leaching tests performed for [La(H(3)nmp)] confirm the heterogeneous nature of the catalytic reaction. Catalytic activity may be attributed to structural defect sites. This assumption is somewhat supported by the much higher catalytic activity of [La(L)] in comparison to [La(H(3)nmp)].


Asunto(s)
Lantano/química , Compuestos Organometálicos/química , Polímeros/química , Temperatura , Cristalografía por Rayos X , Modelos Moleculares , Estructura Molecular , Compuestos Organometálicos/síntesis química , Tamaño de la Partícula , Propiedades de Superficie , Termogravimetría
19.
Acta Crystallogr C ; 67(Pt 6): o198-200, 2011 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-21633159

RESUMEN

The asymmetric unit of the title compound, C(9)H(9)Br(3), is composed of a single molecule. Two bromo substituents are located on one side of the plane of the aromatic ring and the third is on the opposite side, with the molecular unit exhibiting an approximate noncrystallographic C(s) point group. The crystal structure is rich in Br...Br, CH(2)···Br and CH···π weak intermolecular contacts which mediate the crystal packing of individual molecules. These interactions promote a red-shift of a handful of vibrational modes (associated with the pendant -CH(2)Br groups) compared with values from theoretical density functional theory (DFT) calculations.

20.
Acta Crystallogr C ; 67(Pt 2): o57-9, 2011 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-21285502

RESUMEN

The asymmetric unit of the title compound comprises the monohydrated form of the natural product arcyriaflavin A [systematic name: 12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-dione monohydrate], C(20)H(11)N(3)O(2)·H(2)O. Individual molecular units are engaged in hydrogen-bonding interactions, forming two-dimensional zigzag supramolecular layers parallel to the (102) plane. The close packing of the layers is mediated by strong co-operative π-π stacking interactions, in tandem with interlayer hydrogen bonds involving the solvent water molecule.


Asunto(s)
Solventes/química , Agua/química , Carbazoles , Cristalografía por Rayos X , Enlace de Hidrógeno , Estructura Molecular
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