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1.
Langmuir ; 36(41): 12168-12178, 2020 10 20.
Artigo em Inglês | MEDLINE | ID: mdl-32970443

RESUMO

In the wide panorama of diacetylenic lipids, the photoresponsive conjugated 1,3-diyne function is usually encased into the hydrocarbon chain of the amphiphile at a variable distance from the headgroup. Therefore, the polydiacetylene network obtained by polymerization upon UV irradiation of the corresponding liposomes, exploited as sensing function, is embedded in the hydrophobic region of liposomes. Structurally related cationic diacetylenic amphiphiles featuring the conjugated triple bonds proximate to charged nitrogen were synthesized and evaluated in their ability to polymerize under aggregative conditions. The occurrence of polymerization only in certain aggregating conditions was rationalized by nuclear magnetic resonance (NMR) and Langmuir trough experiments.

2.
Molecules ; 25(8)2020 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-32326129

RESUMO

The chemical composition of the inflorescences from four Cannabis sativa L. monoecious cultivars (Ferimon, Uso-31, Felina 32 and Fedora 17), recently introduced in the Lazio Region, was monitored over the season from June to September giving indications on their sensorial, pharmaceutical/nutraceutical proprieties. Both untargeted (NMR) and targeted (GC/MS, UHPLC, HPLC-PDA/FD and spectrophotometry) analyses were carried out to identify and quantify compounds of different classes (sugars, organic acids, amino acids, cannabinoids, terpenoids, phenols, tannins, flavonoids and biogenic amines). All cultivars in each harvesting period showed a THC content below the Italian legal limit, although in general THC content increased over the season. Citric acid, malic acid and glucose showed the highest content in the late flowering period, whereas the content of proline drastically decreased after June in all cultivars. Neophytadiene, nerolidol and chlorogenic acid were quantified only in Felina 32 cultivar, characterized also by a very high content of flavonoids, whereas alloaromadendrene and trans-cinnamic acid were detected only in Uso-31 cultivar. Naringenin and naringin were present only in Fedora 17 and Ferimon cultivars, respectively. Moreover, Ferimon had the highest concentration of biogenic amines, especially in July and August. Cadaverine was present in all cultivars but only in September. These results suggest that the chemical composition of Cannabis sativa L. inflorescences depends on the cultivar and on the harvesting period. Producers can use this information as a guide to obtain inflorescences with peculiar chemical characteristics according to the specific use.


Assuntos
Cannabis/química , Cannabis/crescimento & desenvolvimento , Inflorescência/química , Canabinoides/química , Cromatografia Líquida de Alta Pressão , Flavonoides/química , Flores/química , Cromatografia Gasosa-Espectrometria de Massas , Itália , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Desenvolvimento Vegetal
3.
Ann Bot ; 124(4): 627-644, 2019 10 29.
Artigo em Inglês | MEDLINE | ID: mdl-30715123

RESUMO

BACKGROUND AND AIMS: Hydraulic and chemical signals operate in tandem to regulate systemic plant responses to drought. Transport of abscisic acid (ABA) through the xylem and phloem from the root to shoot has been suggested to serve as the main signal of water deficit. There is evidence that ABA and its ABA-glycosyl-ester (ABA-GE) are also formed in leaves and stems through the chloroplastic 2-C-methylerythritol-5-phosphate (MEP) pathway. This study aimed to evaluate how hormonal and hydraulic signals contribute to optimize stomatal (gs), mesophyll (gm) and leaf hydraulic (Kleaf) conductance under well-watered and water-stressed conditions in Populus nigra (black poplar) plants. In addition, we assessed possible relationships between ABA and soluble carbohydrates within the leaf and stem. METHODS: Plants were subjected to three water treatments: well-watered (WW), moderate stress (WS1) and severe stress (WS2). This experimental set-up enabled a time-course analysis of the response to water deficit at the physiological [leaf gas exchange, plant water relations, (Kleaf)], biochemical (ABA and its metabolite/catabolite quantification in xylem sap, leaves, wood, bark and roots) and molecular (gene expression of ABA biosynthesis) levels. KEY RESULTS: Our results showed strong coordination between gs, gm and Kleaf under water stress, which reduced transpiration and increased intrinsic water use efficiency (WUEint). Analysis of gene expression of 9-cis-epoxycarotenoid dioxygenase (NCED) and ABA content in different tissues showed a general up-regulation of the biosynthesis of this hormone and its finely-tuned catabolism in response to water stress. Significant linear relationships were found between soluble carbohydrates and ABA contents in both leaves and stems, suggesting a putative function for this hormone in carbohydrate mobilization under severe water stress. CONCLUSIONS: This study demonstrates the tight regulation of the photosynthetic machinery by levels of ABA in different plants organs on a daily basis in both well-watered and water stress conditions to optimize WUEint and coordinate whole plant acclimation responses to drought.


Assuntos
Ácido Abscísico , Populus , Carboidratos , Ciclo do Carbono , Desidratação , Humanos , Folhas de Planta , Raízes de Plantas , Estômatos de Plantas , Transpiração Vegetal , Água
4.
Chemphyschem ; 19(17): 2208-2217, 2018 09 05.
Artigo em Inglês | MEDLINE | ID: mdl-29774636

RESUMO

The adsorption behavior of neodymium (Nd3+ ) and yttrium (Y3+ ) cations on synthetic FAU zeolite X in its sodium form (NaX) has been investigated by means of macroscopic (adsorption isotherm determination and thermal analysis) and microscopic measurements (including solid-state NMR spectroscopy and X-ray powder diffraction). The multidisciplinary study reveals some unexpected features. Firstly, adsorption constants of cations are not correlated to their ionic radii or hydration enthalpy. The adsorption constant of Y3+ on NaX was indeed about twice that of Nd3+ , which is the opposite of what could be expected based on the size of the cations. In addition, adsorption was accompanied by partial dealumination of the zeolite framework. The extent of dealumination changed depending on the exchanged cations, with the extent being more significant on the Nd-exchanged zeolite than on the Y-exchanged one. The most interesting finding of this study, however, is the presence of supramolecular clusters composed of water, Nd3+ , residual sodium ions, and extra-framework aluminum at the interface of Nd-exchanged zeolite. The hypothesis that these host-guest complexes are responsible of the significantly different behavior exhibited by NaX towards the adsorption/desorption of Nd3+ and Y3+ has been formulated.

5.
Anal Bioanal Chem ; 409(5): 1405-1413, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27900420

RESUMO

The nuclear magnetic resonance (NMR)-based metabolomic approach was used as analytical methodology to study the urine samples of chronic inflammatory rheumatic disease (CIRD) patients. The urine samples of CIRD patients were compared to the ones of both healthy subjects and patients with multiple sclerosis (MS), another immuno-mediated disease. Urine samples collected from 39 CIRD patients, 25 healthy subjects, and 26 MS patients were analyzed using 1H NMR spectroscopy, and the NMR spectra were examined using partial least squares-discriminant analysis (PLS-DA). PLS-DA models were validated by a double cross-validation procedure and randomization tests. Clear discriminations between CIRD patients and healthy controls (average diagnostic accuracy 83.5 ± 1.9%) as well as between CIRD patients and MS patients (diagnostic accuracy 81.1 ± 1.9%) were obtained. Leucine, alanine, 3-hydroxyisobutyric acid, hippuric acid, citric acid, 3-hydroxyisovaleric acid, and creatinine contributed to the discrimination; all of them being in a lower concentration in CIRD patients as compared to controls or to MS patients. The application of NMR metabolomics to study these still poorly understood diseases can be useful to better clarify the pathologic mechanisms; moreover, as a holistic approach, it allowed the detection of, by means of anomalous metabolic traits, the presence of other pathologies or pharmaceutical treatments not directly connected to CIRDs, giving comprehensive information on the general health state of individuals. Graphical abstract NMR-based metabolomic approach as a tool to study urine samples in CIRD patients with respect to MS patients and healthy controls.


Assuntos
Espectroscopia de Ressonância Magnética/métodos , Metabolômica , Doenças Reumáticas/urina , Adulto , Estudos de Casos e Controles , Doença Crônica , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Esclerose Múltipla/urina
6.
Electrophoresis ; 37(20): 2710-2719, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27490342

RESUMO

An NMR and chemometric analytical approach to classify beers according to their brand identity was developed within the European TRACE project (FP6-2003-FOOD-2-A, contract number: 0060942). Rochefort 8 Trappist beers (47 samples), other Trappist beers (76 samples) and non-Trappist beers (110 samples) were analyzed by 1 H NMR spectroscopy. Selected NMR signals were measured and used to build classification models. Three different classification problems were identified, namely Trappist versus non-Trappist, Rochefort versus Non-Rochefort, and Rochefort 8 versus non-Rochefort 8. In all the three cases, both a discriminant and a modeling approaches were followed, using partial least squares discriminant analysis (PLS-DA) and soft independent modeling of class analogies (SIMCA), respectively, leading to very high classification accuracy as evaluated by external validation. Information regarding chemical composition was also obtained: Trappist beers contain a higher amount of formic and pyruvic acids and a lower amount of acetic acid and alanine with respect to non-Trappist ones. Rochefort beers turned out to have also a higher content of propanol and isopentanol with respect to non-Rochefort samples. Finally, Rochefort 8, shows the highest content of pyruvic acid and the lowest content of gallic, fumaric, acetic acids, adenosine, uridine, 2-phenylethanol, GABA, and alanine.


Assuntos
Cerveja/análise , Cerveja/classificação , Análise de Alimentos/métodos , Espectroscopia de Ressonância Magnética/métodos , Análise Discriminante , Análise dos Mínimos Quadrados , Modelos Químicos , Compostos Orgânicos/análise , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
7.
Pharm Res ; 32(5): 1557-69, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25366547

RESUMO

PURPOSE: To synthesize a new polymeric prodrug based on α,ß-poly(N-2-hydroxyethyl)(2-aminoethylcarbamate)-d,l-aspartamide copolymer bearing amine groups in the side chain (PHEA-EDA), covalently linked to the anticancer drug doxorubicin and to test its potential application in anticancer therapy. METHODS: The drug was previously derivatized with a biocompatible and hydrophilic linker, leading to a doxorubicin derivative highly reactive with amino groups of PHEA-EDA. The PHEA-EDA-DOXO prodrug was characterized in terms of chemical stability. The pharmacokinetics, biodistribution and cytotoxicity of the product was investigated in vitro and in vivo on human breast cancer MCF-7 and T47D cell lines and NOD-SCID mice bearing a MCF-7 human breast carcinoma xenograft. Data collected were compared to those obtained using free doxorubicin. RESULTS: The final polymeric product is water soluble and easily hydrolysable in vivo, due to the presence of ester and amide bonds along the spacer between the drug and the polymeric backbone. In vitro tests showed a retarded cytotoxic effect on tumor cells, whereas a significant improvement of the in vivo antitumor activity of PHEA-EDA-DOXO and a survival advantage of the treated NOD-SCID mice was evidenced, compared to that of free doxorubicin. CONCLUSIONS: The features of the PHEA-EDA-DOXO provide a potential protection of the drug from the plasmatic enzymatic degradation and clearance, an improvement of the blood pharmacokinetic parameters and a suitable body biodistribution. The data collected support the promising rationale of the proposed macromolecular prodrug PHEA-EDA-DOXO for further potential development and application in the treatment of solid cancer diseases.


Assuntos
Aspartame/análogos & derivados , Neoplasias da Mama/tratamento farmacológico , Doxorrubicina/análogos & derivados , Doxorrubicina/uso terapêutico , Poliaminas/química , Poliaminas/uso terapêutico , Pró-Fármacos/química , Pró-Fármacos/uso terapêutico , Animais , Aspartame/química , Aspartame/farmacocinética , Aspartame/uso terapêutico , Mama/efeitos dos fármacos , Mama/patologia , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Doxorrubicina/farmacocinética , Feminino , Humanos , Células MCF-7 , Camundongos Endogâmicos NOD , Camundongos SCID , Poliaminas/farmacocinética , Pró-Fármacos/farmacocinética , Distribuição Tecidual
8.
J Nerv Ment Dis ; 203(2): 87-95, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25602943

RESUMO

The aim of our study was to identify the common and separate mechanisms that might underpin emotion recognition impairment in patients with traumatic brain injury (TBI) and schizophrenia (Sz) compared with healthy controls (HCs). We recruited 21 Sz outpatients, 24 severe TBI outpatients, and 38 HCs, and we used eye-tracking to compare facial emotion processing performance. Both Sz and TBI patients were significantly poorer at recognizing facial emotions compared with HC. Sz patients showed a different way of exploring the Pictures of Facial Affects stimuli and were significantly worse in recognition of neutral expressions. Selective or sustained attention deficits in TBI may reduce efficient emotion recognition, whereas in Sz, there is a more strategic deficit underlying the observed problem. There would seem to be scope for adjustment of effective rehabilitative training focused on emotion recognition.


Assuntos
Lesões Encefálicas/fisiopatologia , Emoções/fisiologia , Expressão Facial , Reconhecimento Visual de Modelos/fisiologia , Esquizofrenia/fisiopatologia , Adulto , Atenção/fisiologia , Função Executiva/fisiologia , Movimentos Oculares/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
9.
Magn Reson Chem ; 53(1): 64-77, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25178927

RESUMO

Consolidation and protection are among the most important treatments usually carried out in conservation of stone artifacts and monuments. In this paper, portable unilateral NMR and conventional techniques were used for investigating new multifunctional treatments based on tetraethoxysilane, silica, and polytetrafluoroethylene nanoparticles. The study was carried out on a very complex and heterogeneous porous stone such as tuff. NMR study allowed to obtain detailed information on the penetration depth of treatments, the hydrophobic effect, and changes in the open porosity caused by treatments. Physical and chemical inhomogeneities between the impregnated layers of tuff and the layers underneath were also detected. The average pores radius and pores interconnection obtained from NMR diffusion measurements were used for the first time to compare effects of different consolidating and/or protective treatments on stone. Because unilateral NMR technique is neither destructive nor invasive, investigation of treatments can be also carried out and optimized directly on buildings and monuments of interest for Cultural Heritage.


Assuntos
Espectroscopia de Ressonância Magnética/métodos , Nanopartículas , Coloides , Difusão , Humanos , Politetrafluoretileno , Porosidade , Silanos , Dióxido de Silício
10.
Molecules ; 20(3): 4088-108, 2015 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-25749679

RESUMO

In this review, fundamental aspects of the untargeted NMR-based methodology applied to fruit characterization are described. The strategy to perform the structure elucidation of fruit metabolites is discussed with some examples of spectral assignments by 2D experiments. Primary ubiquitous metabolites as well as secondary species-specific metabolites, identified in different fruits using an untargeted 1H-NMR approach, are summarized in a comprehensive way. Crucial aspects regarding the quantitative elaboration of spectral data are also discussed. The usefulness of the NMR-based metabolic profiling was highlighted using some results regarding quality, adulteration, varieties and geographical origin of fruits and fruit-derived products such as juices.


Assuntos
Frutas/metabolismo , Espectroscopia de Ressonância Magnética/métodos , Metaboloma
11.
Electrophoresis ; 35(11): 1615-26, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24668393

RESUMO

An NMR analytical protocol based on complementary high and low field measurements is proposed for blueberry characterization. Untargeted NMR metabolite profiling of blueberries aqueous and organic extracts as well as targeted NMR analysis focused on anthocyanins and other phenols are reported. Bligh-Dyer and microwave-assisted extractions were carried out and compared showing a better recovery of lipidic fraction in the case of microwave procedure. Water-soluble metabolites belonging to different classes such as sugars, amino acids, organic acids, and phenolic compounds, as well as metabolites soluble in organic solvent such as triglycerides, sterols, and fatty acids, were identified. Five anthocyanins (malvidin-3-glucoside, malvidin-3-galactoside, delphinidin-3-glucoside, delphinidin-3-galactoside, and petunidin-3-glucoside) and 3-O-α-l-rhamnopyranosyl quercetin were identified in solid phase extract. The water status of fresh and withered blueberries was monitored by portable NMR and fast-field cycling NMR. (1) H depth profiles, T2 transverse relaxation times and dispersion profiles were found to be sensitive to the withering.


Assuntos
Antocianinas/análise , Mirtilos Azuis (Planta)/química , Frutas/química , Espectroscopia de Ressonância Magnética/métodos , Fenóis/análise , Extratos Vegetais/química , Aminoácidos/análise , Carboidratos/análise , Lipídeos/análise , Metaboloma
12.
Chemistry ; 20(26): 8138-48, 2014 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-24890919

RESUMO

The structural and chromatographic characterization of two novel fluorinated mesoporous materials prepared by covalent reaction of 3-(pentafluorophenyl)propyldimethylchlorosilane and perfluorohexylethyltrichlorosilane with 2.5 µm fully porous silica particles is reported. The adsorbents were characterized by solid state (29)Si, (13)C, and (19)F NMR spectroscopy, low-temperature nitrogen adsorption, elemental analysis (C and F), and various chromatographic measurements, including the determination of adsorption isotherms. The structure and abundance of the different organic surface species, as well as the different silanol types, were determined. In particular, the degree of so-called horizontal polymerization, that is, Si-O-Si bridging parallel to the silica surface due to the reaction, under "quasi-dry" conditions, of trifunctional silanizing agents with the silica surface was quantified. Significant agreement was found between the information provided by solid-state NMR, elemental analysis, and excess isotherms regarding the amount of surface residual silanol groups, on the one hand, and the degree of surface functionalization, on the other. Finally, the kinetic performance of the fluorinated materials as separation media for applications in near-ultrahigh-performance liquid chromatography was evaluated. At reduced velocities of about 5.5 (ca. 600 bar backpressure at room temperature) with 3 mm diameter columns and toluene as test compound, reduced plate heights on the order of 2 were obtained on columns of both adsorbents.


Assuntos
Cromatografia Líquida/métodos , Espectroscopia de Ressonância Magnética/métodos , Dióxido de Silício/química , Adsorção , Halogenação
13.
Inorg Chem ; 53(4): 2222-9, 2014 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-24471830

RESUMO

Single phase mixed zirconium phosphate phenylphosphonates, ZrP(PP)x, were prepared by two different synthetic approaches: reaction of gels of nanosized α-zirconium phosphate in propanol with solutions of phenylphosphonic acid (H2PP), leading to the topotactic exchange of monohydrogen phosphate groups with phenylphosphonate groups, and precipitation from propanol solutions of H2PP, phosphoric acid, and zirconyl propionate. In both cases, propanol intercalated compounds were obtained. The x values of the ZrP(PP)x materials prepared by topotactic anion exchange ranged from 0.37 to 0.56 for (H2PP/Zr) molar ratios in the range 0.52-4.16 and [H2PP] = 0.1 M, while a maximum x value of 0.73 was only reached at 60 °C, with (H2PP/Zr) = 4.16 and [H2PP] = 0.31 M. Direct precipitation of ZrP(PP)x provided samples with 0.13 ≤ x ≤ 1.54, for H2PP molar fractions in the range 0.05-0.5 and (P/Zr) molar ratio = 6. At 90% relative humidity, the (H2O/Zr) molar ratio for the precipitated ZrP(PP)x powder samples increased in the range 1.3-3.0 with increasing x and resulted in being higher than that of nanosized ZrP (0.8). The analysis of the X-ray diffraction patterns of the gel and powder samples, together with the hydration data of the powder samples, suggested a structural model in which the random distribution of the phosphate and phenylphosphonate groups creates cavities which can accommodate propanol molecules in the gel samples and water molecules in the hydrated powder samples.

14.
Sensors (Basel) ; 14(4): 6977-97, 2014 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-24755519

RESUMO

In recent years nuclear magnetic resonance (NMR) sensors have been increasingly applied to investigate, characterize and monitor objects of cultural heritage interest. NMR is not confined to a few specific applications, but rather its use can be successfully extended to a wide number of different cultural heritage issues. A breakthrough has surely been the recent development of portable NMR sensors which can be applied in situ for non-destructive and non-invasive investigations. In this paper three studies illustrating the potential of NMR sensors in this field of research are reported.


Assuntos
Cultura , Espectroscopia de Ressonância Magnética/instrumentação , Pinturas , Umidade , Imageamento Tridimensional , Porosidade , Fatores de Tempo
15.
Inorg Chem ; 52(13): 7680-7, 2013 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-23763582

RESUMO

Gels of α-type zirconium(IV) phosphate alkylphosphonates, ZP(Cn)x, were prepared by reacting, at room temperature, propanol intercalated nanosized α-zirconium phosphate (α-ZrP) with propanol solutions of alkylphosphonic acids (H2Cn, n = number of carbon atoms in the alkyl chain = 4, 5, 6), with (H2Cn/Zr) molar ratios in the range 0.4-4.0. (31)P MAS NMR showed the presence of resonances due to the phosphate and phosphonate groups bonded to the Zr atoms mainly by three oxygen atoms, as in the α-type layer. The composition of the ZP(Cn)x materials, obtained by thermogravimetric analysis, ranges from x ≈ 0.2 to x ≈ 1.1. On the basis of the NMR data and of the analysis of the X-ray patterns of gels and powders, it is inferred that the ZP(Cn)x compounds have an α-type layered structure and that the reaction between α-ZrP and H2Cn is a topotactic anion exchange process. The evolution of the X-ray patterns during propanol deintercalation is consistent with a random distribution of the alkylphosphonate groups on the α-type layers which gives rise to porous pathways in the interlayer region. To test the possibility of using ZP(Cn)x as mechanical reinforcement of a polymer matrix, a starch membrane filled with 5 wt % ZP(C6)0.54 was prepared and characterized by stress-strain mechanical tests. Besides an excellent flexibility, this membrane exhibited a proportional increase of the Young's modulus by 230% in comparison with neat starch.

16.
Anal Bioanal Chem ; 405(26): 8669-75, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23978933

RESUMO

NMR stratigraphy was used to investigate in situ, non-destructively and non-invasively, the stratigraphy of hydrogen-rich layers of an ancient Nubian detached mural painting. Because of the detachment procedure, a complex multi-layered artefact was obtained, where, besides layers of the original mural painting, also the materials used during the procedure all became constitutive parts of the artefact. NMR measurements in situ enabled monitoring of the state of conservation of the artefact and planning of minimum representative sampling to validate results obtained in situ by solid-state NMR analysis of the samples. This analysis enabled chemical characterization of all organic materials. Use of reference compounds and prepared specimens assisted data interpretation.

17.
Electrophoresis ; 33(15): 2290-313, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22887151

RESUMO

In this review, four examples of the NMR metabolomic approach to foodstuff investigation are reported. Different types of foodstuff of different origin (namely truffle, kiwifruit, lettuce, and sea bass), with different metabolite composition, processing, and storage procedures have been chosen to demonstrate the versatility and potentiality of NMR in the foodstuff analysis. Fundamental aspects of NMR methodology such as sample preparation, metabolites extraction, quantitative elaboration of spectral data, and statistical analysis have been described. Metabolic profilings of aqueous and/or organic extracts as obtained by one- and two-dimensional NMR experiments have been reported together with the results obtained from their statistical elaboration. Discrimination between wild and farmed sea bass and between genetically modified and wild lettuces as well as changes in the kiwifruit metabolic profiles monitored over the season have been investigated. For each foodstuff, some complementary findings provided by other analytical methods are also described to underline the importance of different analytical approaches to explore specific aspects related to foodstuff.


Assuntos
Análise de Alimentos/métodos , Metabolômica/métodos , Ressonância Magnética Nuclear Biomolecular/métodos , Actinidia/química , Agaricales/química , Animais , Bass , Frutas/química , Lactuca/química , Alimentos Marinhos/análise
18.
Inorg Chem ; 50(22): 11623-30, 2011 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-22013996

RESUMO

Simple addition of zirconyl propionate to phosphoric acid in alcoholic media surprisingly led to the formation, in few minutes, of transparent gels containing solvent intercalated zirconium phosphate (ZrP) nanoparticles with hexagonal shape and a planar size of about 40 nm. With the help of elemental analysis, inductively coupled plasma-optical emission spectrometry (ICP-OES), and (31)P magic angle spinning (MAS) NMR, the nanoparticle composition was formulated as Zr(R)(w)(HPO(4))(x)(H(2)PO(4))(y), in which R can be an hydroxyl or a propionate group. The stoichiometric coefficients for propanol intercalated ZrP are x = 1.43, y = 0.83, and w = 0.32. Solvent elimination at 60 °C gave rise to an increase in the x value and a decrease in the y and w values. X-ray powder diffraction analysis and transmission electron microscopy (TEM) observations showed a concomitant increase in the particle size: planar size and thickness ranged from 90 to 200 nm and from 20 to 85 nm, respectively, depending on the nature of the solvent. A possible mechanism explaining the change in the x, y, and w values, the growth of nanoparticles, and the role of the solvent is proposed. Finally, the possibility of using these gels to disperse the ZrP nanoparticles within the polymer matrix of Nafion117 is shown.

19.
Inorg Chem ; 50(23): 12116-25, 2011 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-22040347

RESUMO

The solid state and solution structure of 2,3-dicyano-5,6-di(2-thienyl)-1,4-pyrazine, [(CN)(2)Th(2)Pyz], and its Pd(II) derivative, [(CN)(2)Th(2)Pyz(PdCl(2))(2)]·H(2)O, formed by reaction of [(CN)(2)Th(2)Pyz] with [(C(6)H(5)CN)(2)PdCl(2)] were characterized by X-ray, UV-visible, (1)H and (13)C NMR, and extended X-ray absorption fine structure (EXAFS) spectral measurements. The X-ray crystal structure of [(CN)(2)Th(2)Pyz] shows the presence of one thienyl ring positioned orthogonal to the rest of the molecule, with the two vicinal thienyl rings lying orthogonal to each other in a rare arrangement. NMR studies of [(CN)(2)Th(2)Pyz] in the solid state and in solutions of dimethylformamide or dimethyl sulfoxide confirm a nonequivalence of the thienyl rings in the solid state and also in solution. EXAFS results indicate that two distinct Pd(II) coordination sites are formed at the di(2-thienyl)pyrazino moiety of [(CN)(2)Th(2)Pyz(PdCl(2))(2)]·H(2)O, with identical Pd-N(pyz) (2.03(3) Å) and Pd-Cl (2.36(3) Å) bond lengths but with different Pd-S1 (2.25(4) Å) and Pd-S2 (3.21(5) Å) bond distances in an overall asymmetric molecular framework. Density functional theory (DFT) and time-dependent DFT (TDDFT) theoretical studies also provide information about the structure and spectral behavior of the precursor and its metalated Pd(II) derivative. (1)H/(13)C NMR and UV-visible spectral measurements were also carried out on two heteropentametallic porphyrazine macrocycles which were prepared by a reaction of PdCl(2) with [Th(8)TPyzPzM] where Th(8)TPyzPz = tetrakis-2,3-[5,6-di-(2-thienyl)-pyrazino]porphyrazinato dianion and M = Mg(II)(H(2)O) or Zn(II). Spectroscopic data on the newly synthesized [(PdCl(2))(4)Th(8)TPyzPzM] compounds suggest that the binding of PdCl(2) involves coordination sites of the type S(2(th))PdCl(2) with the two thienyl rings of each di(2-thienyl)pyrazino fragment bound to Pd(II) in an equivalent manner ("th-th" coordination). This is similar to what was found for the corresponding octapyridinated analogues ("py-py" coordination).

20.
Anal Bioanal Chem ; 400(9): 3151-64, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21491108

RESUMO

Hydrophobic treatment is one of the most important interventions usually carried out in the conservation of stone artifacts and monuments. The analytical study reported in this paper was aimed at answering general questions such as the penetration depth of a hydrophobic treatment into a porous material, its capability to impair the water absorption, how the presence of a treatment may change the open porosity available to the water, and how a treatment may affect the diffusion of water inside a porous structure. Also, inhomogeneities in treated stones due to sharp variations of the amount of the absorbed product in the porous material were evidenced and scaled. The results of this fully non-invasive analytical study were rationalized in terms of new parameters obtained by a suitable process of nuclear magnetic resonance data. These analytical parameters reported here for the first time, namely the hydrophobic efficiency, the penetration depth, and angles describing changes in slope in depth profiles, gave important information in assessing the performance of a treatment.

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