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1.
Mol Biol Rep ; 50(6): 4887-4897, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37072653

RESUMO

BACKGROUND: In Brachiaria sexual reproduction, during ovule development, a nucellar cell differentiates into a megaspore mother cell (MMC) that, through meiosis and mitosis, gives rise to a reduced embryo sac. In aposporic apomictic Brachiaria, next to the MMC, other nucellar cells differentiate into aposporic initials that enter mitosis directly forming an unreduced embryo sac. The IPT (isopentenyltransferase) family comprises key genes in the cytokinin (CK) pathway which are expressed in Arabidopsis during ovule development. BbrizIPT9, a B. brizantha (syn. Urochloa brizantha) IPT9 gene, highly similar to genes of other Poaceae plants, also shows similarity with Arabidopsis IPT9, AtIPT9. In this work, we aimed to investigate association of BbrizIPT9 with ovule development in sexual and apomictic plants. METHODS AND RESULTS: RT-qPCR showed higher BbrizIPT9 expression in the ovaries of sexual than in the apomictic B. brizantha. Results of in-situ hybridization showed strong signal of BbrizIPT9 in the MMC of both plants, at the onset of megasporogenesis. By analyzing AtIPT9 knockdown mutants, we verified enlarged nucellar cell, next to the MMC, in a percentage significantly higher than in the wild type, suggesting that knockout of AtIPT9 gene triggered the differentiation of extra MMC-like cells. CONCLUSIONS: Our results indicate that AtIPT9 might be involved in the proper differentiation of a single MMC during ovule development. The expression of a BbrizIPT9, localized in male and female sporocytes, and lower in apomicts than in sexuals, and effect of IPT9 knockout in Arabidopsis, suggest involvement of IPT9 in early ovule development.


Assuntos
Arabidopsis , Brachiaria , Brachiaria/genética , Arabidopsis/genética , Óvulo Vegetal/genética , Óvulo Vegetal/metabolismo , Poaceae , Reprodução/genética , Regulação da Expressão Gênica de Plantas/genética
2.
ACS Biomater Sci Eng ; 9(4): 1909-1918, 2023 04 10.
Artigo em Inglês | MEDLINE | ID: mdl-36996427

RESUMO

Metal-organic frameworks (MOFs) have high potential as nanoplatforms for the storage and delivery of therapeutic gasotransmitters or gas-releasing molecules. The aim of the present study was to open an investigation into the viability of tricarbonyl-pyrazine-molybdenum(0) MOFs as carbon monoxide-releasing materials (CORMAs). A previous investigation found that the reaction of Mo(CO)6 with excess pyrazine (pyz) in a sealed ampoule gave a mixture comprising a major triclinic phase with pyz-occupied hexagonal channels, formulated as fac-Mo(CO)3(pyz)3/2·1/2pyz (Mo-hex), and a minor dense cubic phase, formulated as fac-Mo(CO)3(pyz)3/2 (Mo-cub). In the present work, an open reflux method in toluene has been optimized for the large-scale synthesis of the pure Mo-cub phase. The crystalline solids Mo-hex and Mo-cub were characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), FT-IR and FT-Raman spectroscopies, and 13C{1H} cross-polarization (CP) magic-angle spinning (MAS) NMR spectroscopy. The release of CO from the MOFs was studied by the deoxy-myoglobin (deoxy-Mb)/carbonmonoxy-myoglobin (MbCO) UV-vis assay. Mo-hex and Mo-cub release CO upon contact with a physiological buffer in the dark, delivering 0.35 and 0.22 equiv (based on Mo), respectively, after 24 h, with half-lives of 3-4 h. Both materials display high photostability such that the CO-releasing kinetics is not affected by irradiation of the materials with UV light. These materials are attractive as potential CORMAs due to the slow release of a high CO payload. In the solid-state and under open air, Mo-cub underwent almost complete decarbonylation over a period of 4 days, corresponding to a theoretical CO release of 10 mmol per gram of material.


Assuntos
Estruturas Metalorgânicas , Estruturas Metalorgânicas/química , Monóxido de Carbono/química , Molibdênio/química , Mioglobina/química , Espectroscopia de Infravermelho com Transformada de Fourier , Pirazinas
3.
Viruses ; 15(2)2023 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-36851755

RESUMO

Papaya sticky disease is caused by the association of a fusagra-like and an umbra-like virus, named papaya meleira virus (PMeV) and papaya meleira virus 2 (PMeV2), respectively. Both viral genomes are encapsidated in particles formed by the PMeV ORF1 product, which has the potential to encode a protein with 1563 amino acids (aa). However, the structural components of the viral capsid are unknown. To characterize the structural proteins of PMeV and PMeV2, virions were purified from Carica papaya latex. SDS-PAGE analysis of purified virus revealed two major proteins of ~40 kDa and ~55 kDa. Amino-terminal sequencing of the ~55 kDa protein and LC-MS/MS of purified virions indicated that this protein starts at aa 263 of the deduced ORF1 product as a result of either degradation or proteolytic processing. A yeast two-hybrid assay was used to identify Arabidopsis proteins interacting with two PMeV ORF1 product fragments (aa 321-670 and 961-1200). The 50S ribosomal protein L17 (AtRPL17) was identified as potentially associated with modulated translation-related proteins. In plant cells, AtRPL17 co-localized and interacted with the PMeV ORF1 fragments. These findings support the hypothesis that the interaction between PMeV/PMeV2 structural proteins and RPL17 is important for virus-host interactions.


Assuntos
Proteínas do Capsídeo , Carica , Aminoácidos , Capsídeo , Proteínas do Capsídeo/genética , Cromatografia Líquida , Látex , Espectrometria de Massas em Tandem , Vírus de RNA/genética
4.
Front Chem ; 10: 1004586, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36300029

RESUMO

A ketodiacid, 4,4'-dicarboxylate-dicumyl ketone (3), has been intercalated into a Zn, Al layered double hydroxide (LDH) by a coprecipitation synthesis strategy. The structure and chemical composition of the resultant hybrid material (LDH-KDA3) were characterized by powder X-ray diffraction (PXRD), FT-IR, FT-Raman and solid-state 13C{1H} NMR spectroscopies, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA), and elemental analysis (CHN). PXRD showed that the dicarboxylate guest molecules assembled into a monolayer to give a basal spacing of 18.0 Å. TGA revealed that the organic guest starts to decompose at a significantly higher temperature (ca. 330°C) than that determined for the free ketodiacid (ca. 230°C). Photochemical experiments were performed to probe the photoreactivity of the ketoacid in the crystalline state, in solution, and as a guest embedded within the photochemically-inert LDH host. Irradiation of the bulk crystalline ketoacid results in photodecarbonylation and the exclusive formation of the radical-radical combination product. Solution studies employing the standard myoglobin (Mb) assay for quantification of released CO showed that the ketoacid behaved as a photoactivatable CO-releasing molecule for transfer of CO to heme proteins, although the photoreactivity was low. No photoinduced release of CO was found for the LDH system, indicating that molecular confinement enhanced the photo-stability of the hexasubstituted ketone. To better understand the behavior of 3 under irradiation, a more comprehensive study, involving excitation of this compound in DMSO-d6 followed by 1H NMR, UV-Vis and fluorescence spectroscopy, was undertaken and further rationalized with the help of time-dependent density functional theory (TDDFT) electronic quantum calculations. The photophysical study showed the formation of a less emissive compound (or compounds). New signals in the 1H NMR spectra were attributed to photoproducts obtained via Norrish type I α-cleavage decarbonylation and Norrish type II (followed by CH3 migration) pathways. TDDFT calculations predicted that the formation of a keto-enol system (via a CH3 migration step in the type II pathway) was highly favorable and consistent with the observed spectral data.

5.
Mater Sci Eng C Mater Biol Appl ; 124: 112053, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33947547

RESUMO

A carbon monoxide-releasing material (CORMA) has been prepared by inclusion of molybdenum hexacarbonyl in a hafnium-based metal-organic framework (MOF) with the UiO-66 architecture. Mo(CO)6 was adsorbed from solution to give supported materials containing 6.0-6.6 wt% Mo. As confirmed by powder X-ray diffraction (PXRD) and SEM coupled with energy dispersive X-ray spectroscopy, neither the crystallinity nor the morphology of the porous host was affected by the loading process. While the general shape of the N2 physisorption isotherms (77 K) did not change significantly after encapsulation of Mo(CO)6, the micropore volume decreased by ca. 20%. Thermogravimetric analysis of the as-prepared materials revealed a weight loss step around 160 °C associated with the decomposition of Mo(CO)6 to subcarbonyl species. Confirmation for the presence of encapsulated Mo(CO)6 complexes was provided by FT-IR and 13C{1H} cross-polarization magic-angle spinning NMR spectroscopies. To test the capability of these materials to behave as CORMAs and transfer CO to heme proteins, the standard myoglobin (Mb) assay was used. While stable in the dark, photoactivation with low-power UV light (365 nm) liberated CO from the encapsulated hexacarbonyl molecules in Mo(6.0)/UiO-66(Hf), leading to a maximum amount of 0.26 mmol CO released per gram of material. Under the simulated physiological conditions of the Mb assay (37 °C, pH 7.4 buffer), minimal leaching of molybdenum occurred, PXRD showed only slight amorphization, and FT-IR spectroscopy confirmed the high chemical stability of the MOF host.


Assuntos
Gasotransmissores , Estruturas Metalorgânicas , Monóxido de Carbono , Háfnio , Molibdênio , Espectroscopia de Infravermelho com Transformada de Fourier
7.
Haematologica ; 106(3): 806-818, 2021 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-31919087

RESUMO

Trypanosomiasis is a parasitic disease affecting both humans and animals in the form of Human African Trypanosomiasis and Nagana disease, respectively. Anemia is one of the most common symptoms of trypanosomiasis, and if left unchecked can cause severe complications and even death. Several factors have been associated with the development of this anemia, including dysregulation of iron homeostasis, but little is known about the molecular mechanisms involved. Here, using murine models, we study the involvement of hepcidin, the key regulator of iron metabolism and an important player in the development of anemia of inflammation. Our data show two stages for the progression of anemia, to which hepcidin contributes a first stage when anemia develops, with a likely cytokine-mediated stimulation of hepcidin and subsequent limitation in iron availability and erythropoiesis, and a second stage of recovery, where the increase in hepcidin then declines due to the reduced inflammatory signal and increased production of erythroid regulators by the kidney, spleen and bone marrow, thus leading to an increase in iron release and availability, and enhanced erythropoiesis. In agreement with this, in hepcidin knockout mice, anemia is much milder and its recovery is complete, in contrast to wild-type animals which have not fully recovered from anemia after 21 days. Besides all other factors known to be involved in the development of anemia during trypanosomiasis, hepcidin clearly makes an important contribution to both its development and recovery.


Assuntos
Anemia , Trypanosoma brucei brucei , Anemia/etiologia , Animais , Eritropoese , Hepcidinas/genética , Ferro , Camundongos
8.
Sci Rep ; 10(1): 3061, 2020 02 20.
Artigo em Inglês | MEDLINE | ID: mdl-32080266

RESUMO

Macrophages are central cells both in the immune response and in iron homeostasis. Iron is both essential and potentially toxic. Therefore, iron acquisition, transport, storage, and release are tightly regulated, by several important proteins. Cytosolic ferritin is an iron storage protein composed of 24 subunits of either the L- or the H-type chains. H-ferritin differs from L-ferritin in the capacity to oxidize Fe2+ to Fe3+. In this work, we investigated the role played by H-ferritin in the macrophages' ability to respond to immune stimuli and to deal with exogenously added iron. We used mice with a conditional deletion of the H-ferritin gene in the myeloid lineage to obtain bone marrow-derived macrophages. These macrophages had normal viability and gene expression under basal culture conditions. However, when treated with interferon-gamma and lipopolysaccharide they had a lower activation of Nitric Oxide Synthase 2. Furthermore, H-ferritin-deficient macrophages had a higher sensitivity to iron-induced toxicity. This sensitivity was associated with a lower intracellular iron accumulation but a higher production of reactive oxygen species. These data indicate that H-ferritin modulates macrophage response to immune stimuli and that it plays an essential role in protection against iron-induced oxidative stress and cell death.


Assuntos
Ferritinas/metabolismo , Ferro/metabolismo , Macrófagos/metabolismo , Oxirredutases/metabolismo , Animais , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/genética , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/genética , Compostos Férricos/farmacologia , Ferritinas/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Hemina/farmacologia , Ferro/farmacologia , Ativação de Macrófagos/efeitos dos fármacos , Ativação de Macrófagos/genética , Macrófagos/citologia , Macrófagos/imunologia , Macrófagos/ultraestrutura , Camundongos , Estresse Oxidativo/efeitos dos fármacos , Estresse Oxidativo/genética , Oxirredutases/genética , Compostos de Amônio Quaternário/farmacologia
9.
Dalton Trans ; 49(13): 3989-3998, 2020 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-31951240

RESUMO

This work reports the synthesis and multifunctionality of 2D layered coordination polymers formulated as [Ln2(H3nmp)2]·xH2O (1, where Ln = Sm3+, Eu3+, Tb3+, Dy3+, Ho3+, Er3+ and Y3+) (x = 1 to 4). We describe detailed synthesis of the materials using various methods [typical hydrothermal reaction (HT), microwave-assisted synthesis (MWAS) and one-pot method (OP)], while discussing the various crystal morphologies which can be fine tuned by varying systematically the conditions. We further explore the multifunctionality of this material by studying its heterogeneous catalytic activity in the ring opening of styrene oxide, its photoluminescence behaviour and its cytotoxicity. A conversion of 88%/100% yield at 4 h/24 h reaction respectively, with excellent selectivity towards 2-methoxy-2-phenylethanol product (100%) was observed. Photoluminescence properties of the optically-active [Eu2(H3nmp)2]·xH2O (1Eu) and the mixed-lanthanide [(Gd0.95Eu0.5)2(H3nmp)2]·xH2O (1GdEu), on the other hand, show potential use for UV-to-visible light converters, with lifetimes of 2.31 ± 0.01 and 2.61 ± 0.01 ms at ambient temperature for 1Eu and 1GdEu samples. Preliminary cytotoxic studies showed no effects on metabolic activity of both in vitro human epithelial kidney (HK-2) and human hepatocellular carcinoma (HepG2) cell lines. A reduction of NR uptake was, however, observed indicating some cytotoxic effect on lysosomal activity.


Assuntos
Complexos de Coordenação/farmacologia , Elementos da Série dos Lantanídeos/farmacologia , Polímeros/farmacologia , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Complexos de Coordenação/síntese química , Complexos de Coordenação/química , Relação Dose-Resposta a Droga , Células Hep G2 , Humanos , Elementos da Série dos Lantanídeos/química , Modelos Moleculares , Estrutura Molecular , Tamanho da Partícula , Polímeros/química , Relação Estrutura-Atividade , Propriedades de Superfície
10.
Physiol Plant ; 168(4): 845-875, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31517991

RESUMO

Somatic embryogenesis in palm trees is, in general, a slow and highly complex process, with a predominance of the indirect route and, consequently, a lack of knowledge about the direct route. We present new knowledge related to the morphological, histochemical and ultrastructural aspects of the transition from somatic to embryogenic cells and direct formation of somatic embryos from mature zygotic embryos of Syagrus oleracea, a palm tree. The results support the general concept that 2,4-dichlorophenoxyacetic acid plays a critical role for the formation of somatic embryos of direct and multicellular origin. Seven days in medium with auxin were enough for the identification of embryogenic cells. These cells had a set of characteristics corresponding to totipotent stem cells. At 14 days on induction medium, nodular formations were observed in the distal region of inoculated embryos, which evolved into globular somatic embryos. At 120 days on induction medium, the quality of the somatic embryos was compromised. The dynamics of the mobilization of reserve compounds was also demonstrated, with emphasis on starch and protein as energy sources required for the embryogenic process. This study shows for the first time the anatomical and ultrastructural events involved in direct somatic embryogenesis in a palm tree and incites the scientific community to return to the discussion of classical concepts related to direct somatic embryogenesis, especially regarding the characteristics and location of determined pre-embryogenic cells.


Assuntos
Arecaceae/citologia , Células Vegetais/ultraestrutura , Técnicas de Embriogênese Somática de Plantas , Ácido 2,4-Diclorofenoxiacético , Meios de Cultura , Ácidos Indolacéticos , Árvores
11.
Dalton Trans ; 48(30): 11508-11519, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31292582

RESUMO

The reaction of the macrocyclic cavitand cucurbit[6]uril (CB[6]) and the diaqua complex [MoO2Cl2(H2O)2] in hydrochloric acid solution gave a water insoluble supramolecular compound with the general composition 2[MoO2Cl2(H2O)2]·CB[6]·xH2O·yHCl·z(CH3COCH3) (2). Single crystal X-ray diffraction (XRD) analysis revealed the presence of barrel-shape supramolecular entities, {CB[6]·10(H2O)}, aligned in layers which are shifted relative to adjacent layers to form a brick-like pattern. The CB[6]/water hydrogen-bonded entities further engage in intermolecular interactions with water, HCl and [MoO2Cl2(H2O)2] molecules to form a three-dimensional (3D) framework. Compound 2 was characterised by thermogravimetric analysis (TGA), IR and Raman vibrational spectroscopy, and 13C{1H} CP MAS NMR. The reference complex [MoO2Cl2(H2O)2]·(diglyme)2 (1) and compound 2 were studied for the oxidative catalytic conversion of olefins (cis-cyclooctene, cyclohexene and styrene) with aqueous H2O2 as oxidant. Using alcohols as solvents, 2 was employed in a one-pot two-stage strategy for converting olefins to alkoxy products, which involves oxidation (with H2O2) and acid chemistry. Mechanistic studies were carried out using different intermediates as substrates, and the type of solvent and substrate scope were investigated. The results demonstrated the ability of the CB[6]/MoVI supramolecular adduct to function as an acid-oxidation multifunctional catalyst, and its recovery and reuse via relatively simple procedures.

12.
Stand Genomic Sci ; 13: 30, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30410642

RESUMO

Bacillus amyloliquefaciens subsp. plantarum strain Fito_F321 is a naturally occurring strain in vineyard, with the ability to colonise grapevine and which unveils a naturally antagonistic potential against phytopathogens of grapevine, including those responsible for the Botryosphaeria dieback, a GTD disease. Herein we report the draft genome sequence of B. amyloliquefaciens subsp. plantarum Fito_F321, isolated from the leaf of Vitis vinifera cv. Merlot at Bairrada appellation (Cantanhede, Portugal). The genome size is 3,856,229 bp, with a GC content of 46.54% that contains 3697 protein-coding genes, 86 tRNA coding genes and 5 rRNA genes. The draft genome of strain Fito_F321 allowed to predict a set of bioactive compounds as bacillaene, difficidin, macrolactin, surfactin and fengycin that due to their antimicrobial activity are hypothesized to be of utmost importance for biocontrol of grapevine diseases.

13.
Molecules ; 24(1)2018 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-30597921

RESUMO

The molybdenum(0)-carbonyl-triazole complexes [Mo(CO)3(L)3] [L = 1,2,3-triazole (1,2,3-trz) or 1,2,4-triazole (1,2,4-trz)] have been prepared and examined as precursors to molybdenum(VI) oxide catalysts for the epoxidation of cis-cyclooctene. Reaction of the carbonyl complexes with the oxidant tert-butyl hydroperoxide (TBHP) (either separately or in situ) gives oxomolybdenum(VI) hybrid materials that are proposed to possess one-dimensional polymeric structures in which adjacent oxo-bridged dioxomolybdenum(VI) moieties are further linked by bidentate bridging triazole (trz) ligands. A pronounced ligand influence on catalytic performance was found and the best result (quantitative epoxide yield within 1 h at 70 °C) was obtained with the 1,2,3-triazole oxomolybdenum(VI) hybrid. Both molybdenum oxide-triazole compounds displayed superior catalytic performance in comparison with the known hybrid materials [MoO3(trz)0.5], which have different structures based on organic-inorganic perovskite-like layers. With aqueous H2O2 as the oxidant instead of TBHP, all compounds were completely soluble and active. A pronounced ligand influence on catalytic performance was only found for the hybrids [MoO3(trz)0.5], and only the 1,2,4-trz compound displayed reaction-induced self-precipitation behavior. An insight into the type of solution species that may be involved in the catalytic processes with these compounds was obtained by separately treating [MoO3(1,2,4-trz)0.5] with excess H2O2, which led to the crystallization of the complex (NH4)1.8(H3O)0.2[Mo2O2(µ2-O)(O2)4(1,2,4-trz)]·H2O. The single-crystal X-ray investigation of this complex reveals an oxo-bridged dinuclear structure with oxodiperoxo groups being further linked by a single triazole bridge.


Assuntos
Alcenos/química , Molibdênio/química , Óxidos/química , Triazóis/química , Catálise , Cinética , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Estrutura Molecular , Espectroscopia de Infravermelho com Transformada de Fourier
14.
Langmuir ; 34(1): 453-464, 2018 01 09.
Artigo em Inglês | MEDLINE | ID: mdl-29231742

RESUMO

Supramolecularly organized host-guest systems have been synthesized by intercalating water-soluble forms of indigo (indigo carmine, IC) and thioindigo (thioindigo-5,5'-disulfonate, TIS) in zinc-aluminum-layered double hydroxides (LDHs) and zinc-layered hydroxide salts (LHSs) by coprecipitation routes. The colors of the isolated powders were dark blue for hybrids containing only IC, purplish blue or dark lilac for cointercalated samples containing both dyes, and ruby/wine for hybrids containing only TIS. The as-synthesized and thermally treated materials were characterized by Fourier transform infrared, Fourier transform Raman, and nuclear magnetic resonance spectroscopies, powder X-ray diffraction, scanning electron microscopy, and elemental and thermogravimetric analyses. The basal spacings found for IC-LDH, TIS-LDH, IC-LHS, and TIS-LHS materials were 21.9, 21.05, 18.95, and 21.00 Å, respectively, with intermediate spacings being observed for the cointercalated samples that either decreased (LDHs) or increased (LHSs) with increasing TIS content. UV-visible and fluorescence spectroscopies (steady-state and time-resolved) were used to probe the molecular distribution of the immobilized dyes. The presence of aggregates together with the monomer units is suggested for IC-LDH, whereas for TIS-LDH, IC-LHS, and TIS-LHS, the dyes are closer to the isolated situation. Accordingly, while emission from the powder H2TIS is strongly quenched, an increment in the emission of about 1 order of magnitude was observed for the TIS-LDH/LHS hybrids. Double-exponential fluorescence decays were obtained and associated with two monomer species interacting differently with cointercalated water molecules. The incorporation of both TIS and IC in the LDH and LHS hosts leads to an almost complete quenching of the fluorescence, pointing to a very efficient energy transfer process from (fluorescent) TIS to (nonfluorescent) IC.

15.
RSC Adv ; 8(29): 16294-16302, 2018 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-35542229

RESUMO

The synthesis of molybdenum(0) tricarbonyl and tetracarbonyl complexes of the form [Mo(CO)3(ptapzpy)Br] (1) and cis-[Mo(CO)4(ptapzpy)]Br (2) is reported, where ptapzpy = 2-(1-propyltrimethylammonium-3-pyrazolyl)pyridine. Preparation of these derivatives was accomplished either through thermal replacement of CO in Mo(CO)6 (for 1) or substitution under milder conditions of piperidine ligands in the precursor cis-[Mo(CO)4(pip)2] (for 2). The crystal structures of the ligand [ptapzpy]Br and complexes 1 and 2 were determined. Thermal treatment of 2 at 125-150 °C leads to mono decarbonylation and formation of 1. On the other hand, oxidative decarbonylation of 1 and 2 by reaction with tert-butylhydroperoxide (TBHP, 10 equiv.) gives a molybdenum oxide hybrid material formulated as [Mo3O9([ptapzpy]Br)2]·nH2O (3), which was characterised by FT-IR and Raman spectroscopy, thermogravimetric analysis, and 13C{1H} CP MAS NMR spectroscopy. Compounds 1-3 were effective (pre)catalysts for the epoxidation of cis-cyclooctene at 55 °C with aqueous H2O2 or TBHP (slightly better results were obtained with the former). The characterisation of the Mo-containing solids isolated after the catalytic reaction showed that poorly soluble ß-octamolybdate salts, (L) x [Mo8O26], were formed from 1-3 with TBHP and from 1 with H2O2, while soluble oxoperoxo species were formed from 3 with H2O2. These findings helped to explain the different catalytic performances obtained.

16.
Phys Chem Chem Phys ; 19(32): 21548-21555, 2017 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-28766611

RESUMO

Temperature-dependent 57Fe Mössbauer effect (ME) spectroscopic studies were carried out on ferrocene (Fc), 1,1'-dimethylferrocene (1,1'(CH3)2Fc) and ferrocenium hexafluorophosphate (FcPF6) guest species in cucurbit[n]uril (n = 7, 8) inclusion complexes. The solid inclusion complexes were isolated by freeze-drying of dilute aqueous solutions and/or microwave-assisted precipitation from concentrated mixtures. The presence of genuine 1 : 1 (host : guest) inclusion complexes in the isolated solids was supported by liquid-state 1H and solid-state 13C{1H} MAS NMR, elemental and thermogravimetric analyses, powder X-ray diffraction, FTIR spectroscopy, and diffuse reflectance UV-Vis spectroscopy. The ME spectra of the complexes CB7·Fc and CB7·1,1'(CH3)2Fc consist of well-resolved doublets with hyperfine parameters (isomer shift and quadrupole splitting at 90 K) and temperature-dependent recoil-free fraction data that are very similar to those for the neat parent compounds, Fc and 1,1'(CH3)2Fc, suggesting that the organometallic guest molecules do not interact significantly with the host environment over the experimental temperature range. The ME spectra for CB7·FcPF6 and CB8·FcPF6 consist of a major broad line resonance attributed to a paramagnetic FeIII site. From the temperature-dependence of the recoil-free fraction it is evident that the charged guest species in these systems interact with the host environment significantly more strongly than was observed in the case of the neutral guest species, Fc and 1,1'(CH3)2Fc. Moreover, the ME data indicate that the vibrational amplitude of the ferrocenium guest molecule is significantly larger in the CB8 host molecule than in the CB7 homologue, as expected on the basis of the different cavity sizes.

17.
Tob Control ; 26(1): 46-52, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-26790924

RESUMO

BACKGROUND: Over the past decade e-cigarettes have established themselves in the global market. E-cigarettes triggered much interest in relation to their content and efficacy as smoking cessation tools, but less attention has been paid to users and environmental safety warnings and guidance. Several regulations have been introduced to promote their safe handling and disposal. From May 2016, liquids and cartridges will be regulated by European Community Directives (ECDs) 2001/83/EC and 93/42/EEC, or 2014/40/EU if marketed as tobacco-related products. Currently, manufacturers and distributors must abide by the Chemical (Hazard Information and Packaging for Supply) Regulations 2009 (CHIP) or Classification, Labelling and Packaging Regulations (CLP), the latter replacing CHIP in June 2015. OBJECTIVE: In this work, the compliance of marketed e-liquids and e-cigarettes with current European Union and UK legislations is assessed. RESULTS: E-liquids and e-cigarettes (21 and 9 brands, respectively) were evaluated. Evidence of non-compliance was found in relation to the CHIP/CLP toxic (13%) and environmental (37%) pictograms, tactile warning (23%), nominal amount of solution (30%), supplier contact telephone number and address (40%). None of the evaluated e-cigarettes displayed information on the correct disposal/recycling of batteries in line with the ECD 2006/66/EC. CONCLUSIONS: More stringent enforcement of regulations is needed to ensure not only the user's safety and awareness, but also the safeguarding of the environment.


Assuntos
Embalagem de Medicamentos/legislação & jurisprudência , Sistemas Eletrônicos de Liberação de Nicotina , Regulamentação Governamental , Rotulagem de Produtos/legislação & jurisprudência , União Europeia , Humanos , Reino Unido
18.
Chemphyschem ; 18(5): 564-575, 2017 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-27992104

RESUMO

Steady-state and time-resolved absorption and fluorescence measurements are reported for Congo Red (CR) in aqueous and dimethylsulfoxide (DMSO) solutions. The very low fluorescence quantum yield (≈10-4 ) for CR in dilute solutions together with the absence of a triplet state indicates that internal conversion is the dominant deactivation route with more than 99.99 % of the quanta loss (attributed to the energy gap law for radiationless transitions). Although no direct evidence for trans-cis photoisomerization was obtained from absorption or fluorescence data, the global analysis of fs-transient absorption data indicates the presence of a photoproduct with a lifetime of ≈170 ps that is suggested to be associated with such a process. Spectral data for more concentrated CR solutions indicate the presence of oblique or twisted J-type aggregates. These results are compared with spectra for CR in the solid state (sodium salt) and intercalated in a layered double hydroxide via a one-step co-precipitation route. Powder XRD and electronic spectral data for the nanohybrid indicate that the CR guest molecules are intercalated as a monolayer consisting of slipped cofacial J-type aggregates.

19.
Dalton Trans ; 45(42): 17042-17052, 2016 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-27711763

RESUMO

Inclusion complexes of ferrocene (Fc) with cucurbit[n]urils (n = 7, 8) have been prepared via a rapid microwave-assisted hydrothermal approach. Solids were isolated and characterised by elemental analysis, powder X-ray diffraction (PXRD), spectroscopic, and thermoanalytical methods. The UV-Vis spectra support the presence of Fc in Fc@CB7 and a mixture of Fc and ferrocenium ions in Fc@CB8. Partial oxidation of Fc to Fc+ takes place in situ mainly due to the presence of acid of crystallisation in CB8. On the basis of PXRD, the complex Fc@CB8 is classified into an isostructural series that is formed by several CB8-containing compounds that crystallise in the space group I41/a and have similar unit cell dimensions and CB8 packing motifs. The FT-IR and Raman spectra of Fc@CB7 are compared with those of the CB7 host and the Fc guest starting materials, revealing significant frequency shifts of some Fc-centered vibrational modes upon complexation. Blueshifts of the Fe-Cp stretching and ring tilt bands are attributed to encapsulation of Fc monomers in a constrained environment, leading to restricted motion effects and/or a change in the Fc conformation from staggered to eclipsed. The absence of comparable shifts for Fc@CB8 point to a weaker host-guest interaction as a consequence of the larger cavity size. The different host-guest interactions are also evident through a comparison of the 13C{1H} CP MAS NMR spectra. Thermogravimetric analysis for the inclusion compounds reveals that sublimation of Fc is inhibited by molecular encapsulation to the extent that oxidative decomposition of the organoiron species takes place concurrently with cucurbituril decomposition, leading to the formation of hematite, α-Fe2O3.

20.
Dalton Trans ; 45(38): 15242-8, 2016 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-27603728

RESUMO

The oxidative desulfurization of model and real diesel has been studied using the complex [MoO2Cl2(4,4'-di-tert-butyl-2,2'-bipyridine)] as (pre)catalyst, aq. H2O2 as oxidant, and an ionic liquid as extraction solvent. Under moderate conditions (50 °C) and short reaction times (<3 h), dibenzothiophene, 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene could be completely removed from the model diesel. The (pre)catalyst 1 was transformed in situ to the active catalyst [MoO(O2)2(di-tBu-bipy)]. By sequentially performing extractive desulfurization and ECODS steps, 76% sulfur removal was achieved for a real diesel (Sinitial = 2300 ppm). For both the model and real diesels, the catalyst/IL phase could be easily recycled and reused with no loss of desulfurization efficiency.

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