Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 16 de 16
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
Angew Chem Int Ed Engl ; 58(41): 14644-14652, 2019 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-31381224

RESUMO

Cyclopenta[hi]aceanthrylenes (CPAs) have been functionalized at two of the peripheral positions with electronically inert trimethylsilylethynyl (1), as well as with electron-donating 4-ethynyl-N,N-dimethylaniline (2), ethynyl ZnII phthalocyanine (3), and ethynyl ZnII porphyrin (4) units. Consistent with X-ray crystal structures of 2 and 4, analyses of absorption and fluorescence of 2-4 point to strong electronic communication between the CPA and the peripheral units, affording quadrupolar electron donor-acceptor-donor charge-transfer conjugates. By virtue of their quadrupolar/dipolar charge-transfer characters in the excited state, 2-4 exhibit fluoro-solvatochromism. Transient absorption spectroscopy confirmed delocalized quadrupolar ground states and formation of weakly solvent stabilized quadrupolar singlet excited states. The latter transform into strongly stabilized dipolar excited states before deactivating to the ground state in 2 and give rise to a fully charge separated state in 3 and 4.

2.
Clín. investig. arterioscler. (Ed. impr.) ; 29(6): 239-247, nov.-dic. 2017. tab
Artigo em Inglês | IBECS | ID: ibc-169581

RESUMO

Background: Knowledge about the harmful effects of high levels of low-density lipoprotein cholesterol (cLDL) in adults increased after the publication of various guidelines, leading to closer control and more treatment. We hypothesized that these health care changes would result in an overall improvement in the lipid profile of the population. Objective: To determine the evolution of the lipid profile in the population of Spain from the Diet and Risk of Cardiovascular Disease in Spain cohort. Methods: A comparison was made between the baseline population-based probabilistically sampled DRECE cohort (DRECE 1 study, 1992-1994, n=4787) and its 13 years later revisit (DRECE 3 study, 2005-2007). A cross-sectional comparison was made of the overall population of DRECE1 and DRECE3, including only individuals aged 20 to 60 years (inter-individual variations). For subjects participating in both DRECE1 and DRECE3 (n=1039), individual variations over time (intra-individual analyses) were examined. Results: In the overall population, the prevalence of lipid-lowering therapy increased from 3.8% in DRECE1 to 10.7% in DRECE3. Comparing the lipid profile of the population aged 20-60 years in DRECE1 with the same age group in DRECE3, an overall decrease is observed in total cholesterol from a mean of 203.31mg/dl (SD 43.51) in 1992-1994 to 196.31mg/dl (SD 38.53) in 2005-2007, and in cLDL from a mean of 125.78mg/dl (SD 38.53) to 121.37mg/dl (SD 34.22). The proportion of the population with total cholesterol >200mg/dl decreased from 51% in DRECE1 to 47% in DRECE3, although this difference did not reach statistical significance (p=0.077). As regards the intra-individual analyses, total cholesterol increased from DRECE1 to DRECE3 in men and women younger than 40 years at baseline, but decreased in those who were older. Index of individuality for total cholesterol, cLDL, cHDL and triglycerides ranged from 0.53 to 0.87. Conclusions: The lipid profile of the Spanish population improved between 1992-1994 and 2005-2007. Within individuals, lipid concentrations, especially total cholesterol and cLDL have increased, although the trend is favorable in the middle-age group (40-59 years). These changes seem to be due to several causes, impacted by dietary and lifestyle factors, and also by a greater emphasis in lipid-lowering therapy in middle-aged people. Lipid parameters had a low index of individuality, which limits their usefulness as population reference values (AU)


Antecedentes: Los efectos nocivos de los altos niveles de colesterol ligado a lipoproteínas de baja densidad (cLDL) han sido ampliamente difundidos en la literatura científica y popular. Nuestra hipótesis es que estas recomendaciones han influido eficazmente en el perfil lípido de la población española. Objetivo: Determinar la evolución del perfil de lípidos en la población de España a partir de la cohorte Dieta y riesgo de enfermedad cardiovascular en España (DRECE). Métodos: Se comparó la cohorte de partida DRECE (estudio DRECE1, 1992-1994, n=4.787), procedente de muestreo probabilístico poblacional, con su reevaluación a los 13 años (estudio DRECE3, 2005-2007). Se compararon de modo transversal las muestras DRECE1 y DRECE3, incluyendo solo sujetos entre 20 y 60 años (variaciones interindividuales). De los sujetos que participaron en ambos estudios (n=1.039) se examinaron las variaciones interindividuales a lo largo del tiempo (análisis intraindividual). Resultados: En la población general, la prevalencia de la terapia hipolipidemiante aumentó de 3,8% en DRECE1 a 10,7% en DRECE3. Al comparar el perfil lipídico de la población de 20 a 60 años en DRECE1 con el mismo grupo de edad en DRECE3 disminuye la media del colesterol total de 203,31mg/dl (DS 43,51) en 1992-1994 a 196,31mg/dl (DS 38,53) en 2005-2007, la media del cLDL disminuye de 125,78mg/dl (DS 38,53) a 121,37mg/dl (DS 34,22). La proporción de la población con colesterol total>200mg/dl se redujo de 51% en DRECE1 al 47% en DRECE3, aunque esta diferencia no fue significativa (p=0,077). Respecto del análisis intraindividual el colesterol total aumentó de DRECE1 a DRECE3 en hombres y mujeres menores de 40 años al inicio de la cohorte, y descendió en los mayores de 40. El índice de individualidad del colesterol total, cLDL, cHDL y triglicéridos osciló entre 0,53 y 0,87. Conclusiones: El perfil lipídico de la población española mejoró entre 1992-1994 y 2005-2007. La concentración intraindividual de lípidos aumentó ligeramente, especialmente el colesterol total y cLDL, pero la tendencia fue más favorable en los sujetos de edad media (40-59 años). Estos cambios parecen ser multicausales, influidos por factores dietéticos y de estilo de vida, y también por un mayor énfasis en la terapia hipolipidemiante en sujetos en edad media. Los parámetros lipídicos tenían un bajo índice de individualidad, lo que limita su utilidad como valores de referencia poblacionales (AU)


Assuntos
Humanos , Masculino , Feminino , Adulto Jovem , Adulto , Pessoa de Meia-Idade , Lipídeos/análise , Doenças Cardiovasculares/epidemiologia , Doenças Cardiovasculares/prevenção & controle , Colesterol/análise , Triglicerídeos/análise , Transtornos do Metabolismo dos Lipídeos/dietoterapia , Dieta Mediterrânea , Estudos de Coortes , Análise Estatística , Transtornos do Metabolismo dos Lipídeos/diagnóstico
3.
Clin Investig Arterioscler ; 29(6): 239-247, 2017.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-29037827

RESUMO

BACKGROUND: Knowledge about the harmful effects of high levels of low-density lipoprotein cholesterol (cLDL) in adults increased after the publication of various guidelines, leading to closer control and more treatment. We hypothesized that these health care changes would result in an overall improvement in the lipid profile of the population. OBJECTIVE: To determine the evolution of the lipid profile in the population of Spain from the Diet and Risk of Cardiovascular Disease in Spain cohort. METHODS: A comparison was made between the baseline population-based probabilistically sampled DRECE cohort (DRECE 1 study, 1992-1994, n=4787) and its 13 years later revisit (DRECE 3 study, 2005-2007). A cross-sectional comparison was made of the overall population of DRECE1 and DRECE3, including only individuals aged 20 to 60 years (inter-individual variations). For subjects participating in both DRECE1 and DRECE3 (n=1039), individual variations over time (intra-individual analyses) were examined. RESULTS: In the overall population, the prevalence of lipid-lowering therapy increased from 3.8% in DRECE1 to 10.7% in DRECE3. Comparing the lipid profile of the population aged 20-60 years in DRECE1 with the same age group in DRECE3, an overall decrease is observed in total cholesterol from a mean of 203.31mg/dl (SD 43.51) in 1992-1994 to 196.31mg/dl (SD 38.53) in 2005-2007, and in cLDL from a mean of 125.78mg/dl (SD 38.53) to 121.37mg/dl (SD 34.22). The proportion of the population with total cholesterol >200mg/dl decreased from 51% in DRECE1 to 47% in DRECE3, although this difference did not reach statistical significance (p=0.077). As regards the intra-individual analyses, total cholesterol increased from DRECE1 to DRECE3 in men and women younger than 40 years at baseline, but decreased in those who were older. Index of individuality for total cholesterol, cLDL, cHDL and triglycerides ranged from 0.53 to 0.87. CONCLUSIONS: The lipid profile of the Spanish population improved between 1992-1994 and 2005-2007. Within individuals, lipid concentrations, especially total cholesterol and cLDL have increased, although the trend is favorable in the middle-age group (40-59 years). These changes seem to be due to several causes, impacted by dietary and lifestyle factors, and also by a greater emphasis in lipid-lowering therapy in middle-aged people. Lipid parameters had a low index of individuality, which limits their usefulness as population reference values.


Assuntos
LDL-Colesterol/sangue , Colesterol/sangue , Hipolipemiantes/administração & dosagem , Lipídeos/sangue , Adulto , Fatores Etários , HDL-Colesterol/sangue , Estudos de Coortes , Estudos Transversais , Dieta , Feminino , Humanos , Estilo de Vida , Masculino , Pessoa de Meia-Idade , Fatores Sexuais , Espanha , Triglicerídeos/sangue , Adulto Jovem
4.
Angew Chem Int Ed Engl ; 55(18): 5560-4, 2016 04 25.
Artigo em Inglês | MEDLINE | ID: mdl-27010677

RESUMO

A cycloaddition-retroelectrocyclization reaction between tetracyanoethylene and two zinc phthalocyanines (Zn(II) Pcs) bearing one or four anilino-substituted alkynes has been used to install a strong, electron-accepting tetracyanobuta-1,3-diene (TCBD) between the electron-rich Zn(II) Pc and aniline moieties. A combination of photophysical, electrochemical, and spectroelectrochemical investigations with the Zn(II) Pc-TCBD-aniline conjugates, which present panchromatic absorptions in the visible region extending all the way to the near infrared, show that the formal replacement of the triple bond by TCBD has a dramatic effect on their ground- and excited-state features. In particular, the formation of extremely intense, ground-state charge-transfer interactions between Zn(II) Pc and the electron-accepting TCBD were observed, something unprecedented not only in Pc chemistry but also in TCBD-based porphyrinoid systems.

5.
Chemistry ; 19(4): 1457-65, 2013 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-23197446

RESUMO

A series of homoleptic ([Tb(III)(Pc)(2) ]) and heteroleptic ([Tb(III)(Pc)(Pc')]) Tb(III) bis(phthalocyaninate) complexes that contain different peripheral substitution patterns (i.e., tert-butyl or tert-butylphenoxy groups) have been synthesized in their neutral radical forms and then reduced into their corresponding anionic forms as stable tetramethylammonium/tetrabutylammonium salts. All of these compounds were spectroscopically characterized and their magnetic susceptibility properties were investigated. As a general trend, the radical forms exhibited larger energy barriers for spin reversal than their corresponding reduced compounds. Remarkably, heteroleptic complexes that contain electron-donor moieties on one of the two Pc ligands show higher effective barriers and blocking temperatures than their homoleptic derivatives. This result is assigned to the elongation of the N-Tb distances in the substituted macrocycle, which brings the terbium(III) ion closer to the unsubstituted Pc, thus enhancing the ligand-field effect. In particular, heteroleptic [Tb(III) (Pc)(Pc')] complex 4, which contains one octa(tert-butylphenoxy)-substituted Pc ring and one bare Pc ring, exhibits the highest effective barrier and blocking temperature for a single-molecule magnet reported to date.

6.
Asclepio ; 64(1): 213-250, ene.-jun. 2012. tab
Artigo em Inglês | IBECS | ID: ibc-101239

RESUMO

In this article I shall concentrate on Antoine Thomas’ illness and death (July 28, 1709) in Peking. This will serve as a case study to elucidate certain aspects of the role played by Jesuit medicine, i.e. Jesuit physicians and Jesuit drugs, at the court of the Kangxi emperor (r. 1662-1722), the first of the three great rulers of the Qing dynasty (1644-1911). As a first step the network of power, as reflected in the so-called medical palace memorials, will be presented in order to arrive at a more comprehensive evaluation of the medical involvement of the Jesuits, as practising physicians, suppliers of foreign drugs and as patients. It will be shown that the circumstances of Thomas’illness and death must be based on a political and social analysis of the role of court medicine as patronised by the Kangxi emperor. Secondly, the case study of Antoine Thomas will also allow us to reflect on the delocalisation and appropriation of theriac at the Chinese court - one of the foreign drugs in the supply of which Jesuits might have been participated. Last but not least, I shall introduce a number of references in archival documents which throw some additional light on Thomas’illness and death, and how they were perceived and dealt with in the imperial court(AU)


En el presente artículo me centro en la enfermedad y muerte de Antoine Thomas (28 de Julio, 1709) en Beijing. Lo cual servirá como estudio para aclarar ciertos aspectos del papel jugado por la medicina Jesuita, es decir, médicos Jesuitas y medicinas Jesuitas en la corte del emperador Kangxi (r. 1662-1722), el primero de los tres grandes emperadores de la dinastía Qing (1644-1911). Primero se presentará la red de poder, según se ve reflejada en los llamados memoriales de palacio de medicina, para poder llegar a una evaluación más profunda de la involucración médica de los Jesuitas, como médicos practicantes, proveedores de medicamentos extranjeros y como pacientes. Se demostrará que las circunstancias de la enfermedad y muerte de Thomas han de basarse en un análisis político y social del papel de la medicina de corte promovida por el emperador Kangxi. En segundo lugar, el estudio sobre Antoine Thomas también nos permitirá reflexionar sobre la deslocalización y apropiación de la teriaca en la corte china - uno de los medicamentos extranjeros en cuyo suministro posiblemente participaran los Jesuitas. Para terminar, presentaré numerosas referenciasen documentos de archivo que arrojarán algo más de luz sobre la enfermedad y muerte de Thomas, y cómo fueron percibidas y tratadas en la corte imperial(AU)


Assuntos
Humanos , História da Medicina , Preparações Farmacêuticas/história , Medicina Tradicional Chinesa/história , Plantas Medicinais
7.
Rev. lab. clín ; 5(1): 18-27, ene.-mar. 2012.
Artigo em Espanhol | IBECS | ID: ibc-99799

RESUMO

Introducción. Los resultados de los programas de garantía de calidad indican que existen diferencias significativas entre los métodos homogéneos disponibles para la medición del colesterol HDL. Sin embargo, la posible influencia de efectos matriz en las muestras liofilizadas empleadas y la ausencia de un valor verdadero en estas muestras, hace difícil la valoración completa de estos métodos. En este estudio experimental multicéntrico hemos comparado los métodos homogéneos más utilizados en nuestro medio, con respecto al de precipitación de ácido fosfotúngstico-MgCl2. Material y métodos. Cada laboratorio procesó unas 100 muestras de suero de pacientes por uno o dos métodos homogéneos y envió alícuotas congeladas de las muestras analizadas al laboratorio central donde se procesaron por el método de precipitación. Resultados. Las imprecisiones de los métodos homogéneos fueron buenas e inferiores a las de precipitación, que cumplía las especificaciones de calidad para sesgo y error total (ET). Sin embargo, no todos los métodos homogéneos cumplían los objetivos de calidad mínimos, pues algunos procedimientos producían sesgos positivos muy altos (en relación al método de comparación) y uno un sesgo negativo muy bajo. El estudio de la concordancia, realizado estratificando a los pacientes según las concentraciones de colesterol HDL, mostró diferencias entre los métodos. Conclusiones. Estos resultados sugieren que existen discrepancias en la valoración de las magnitudes obtenidas con los métodos homogéneos, probablemente generada por una elevada inexactitud en algunos de ellos y que es conveniente que los laboratorios conozcan las caracteristicas de imprecisión y sesgo del metodo directo que utilizan con respecto al de referencia (AU)


Introduction. The results of quality assurance programs suggest that there are significant differences between the homogeneous methods available for the measurement of HDL cholesterol. However, the possible influence of matrix effects in the lyophilized samples used and the absence of a true value in these samples means that a full assessment of these methods cannot be made. In this multicentre pilot study we compared the most used homogeneous methods in our country with the phosphotungstic acid-MgCl2 method. Material and methods. Each laboratory processed about one hundred serum samples from patients with one or two homogeneous methods and sent frozen aliquots of the samples in special packaging with dry ice to the central laboratory where they were processed by the precipitation method. Results. The imprecision of homogeneous methods were good and lower than those of the precipitation method, and met the quality specifications for bias and total error (TE). However, not all homogeneous methods met the minimum quality objectives, as some procedures produced a very high positive bias (relative to the comparison method) and one, a low negative bias. In addition, the study of the agreement between methods, made by stratifying patients according to HDL cholesterol concentrations, showed differences. Conclusions. These results suggest that there are discrepancies in the assessment of the levels obtained with homogeneous methods, probably due to a high inaccuracy in some of them, and it is advised that the laboratories be aware of the characteristics of inaccuracy and bias of the direct method used compared to the reference method (AU)


Assuntos
/organização & administração , /normas , Ácido Fosfotúngstico/síntese química , Ácido Fosfotúngstico , Manejo de Espécimes/instrumentação , Manejo de Espécimes/métodos , HDL-Colesterol/análise , HDL-Colesterol/síntese química , HDL-Colesterol/metabolismo , Manejo de Espécimes/normas , Manejo de Espécimes/tendências , Manejo de Espécimes , Viés de Seleção , Sistemas de Informação em Laboratório Clínico/normas , Sistemas de Informação em Laboratório Clínico , Ciência de Laboratório Médico/métodos
8.
Nanotechnology ; 22(36): 365708, 2011 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-21844643

RESUMO

A nanomechanical testing set-up is developed by integrating an atomic force microscope (AFM) for force measurements with a scanning electron microscope (SEM) to provide imaging capabilities. Electrospun nanofibers of polyvinyl alcohol (PVA), nylon-6 and biological mineralized collagen fibrils (MCFs) from antler bone were manipulated and tensile-tested using the AFM-SEM set-up. The complete stress-strain behavior to failure of individual nanofibers was recorded and a diversity of mechanical properties observed, highlighting how this technique is able to elucidate mechanical behavior due to structural composition at nanometer length scales.


Assuntos
Teste de Materiais/métodos , Microscopia de Força Atômica/métodos , Nanofibras/química , Resistência à Tração , Animais , Caprolactama/análogos & derivados , Caprolactama/química , Cervos , Colágenos Fibrilares/química , Colágenos Fibrilares/ultraestrutura , Interferometria , Lasers , Microscopia Eletrônica de Varredura , Nanofibras/ultraestrutura , Polímeros/química , Álcool de Polivinil/química
9.
Dalton Trans ; 40(15): 3979-88, 2011 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-21416102

RESUMO

Conjugated copolymer derivatives of poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) and poly(3-hexylthiophene) (P3HT) containing 10% of alkyne functionalities in the side chains have been prepared using the sulfinyl precursor route and the Rieke method, respectively. With the aim of expanding the absorption range of these conjugated polymers for their use in bulk heterojunction (BHJ) polymer:fullerene solar cells, appropriate phthalocyanine (Pc) molecules have been covalently bound through a post-polymerization "click chemistry" reaction between the alkyne functionalities in the side chains of the copolymers and a Pc functionalized with an azide moiety. The resulting poly(p-phenylenevinylene)-Pc (PPV-Pc) material holds a 9 mol% content of Pcs, while the polythiophene-Pc material (PT-Pc) contains a 8 mol% of Pc-functionalization in the side chains. As expected, the presence of the Pc contributes to the extension of the absorption up to 700 nm. BHJ solar cells have been prepared using PPV-Pc and PT-Pc materials in combination with PCBM. Although the Pc absorption contributes to the generation of photocurrent, the overall power conversion efficiencies (PCE) obtained from these cells are lower than those obtained with BHJ P3HT:PCBM (1:1) and MDMO-PPV:PCBM (1:4) solar cells. A plausible explanation could be the moderate solubility of the PPV-Pc and PT-Pc materials that limits the processing into thin films.

10.
J Am Chem Soc ; 132(43): 15435-44, 2010 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-20929228

RESUMO

The synthesis and characterization of a series of hybrid organic-inorganic [2]rotaxanes is described. The ring components are heterometallic octa- ([Cr(7)MF(8)(O(2)C(t)Bu)(16)]; M = Co, Ni, Fe, Mn, Cu, Zn, and Cd) nuclear cages in which the metal centers are bridged by fluoride and pivalate ((t)BuCO(2)(-)) anions; the thread components feature dialkylammonium units that template the formation of the heterometallic rings about the axle to form the interlocked structures in up to 92% yield in conventional macrocyclization or one-pot 'stoppering-plus-macrocyclization' strategies. The presence in the reaction mixture of additives (secondary or tertiary amines or quaternary ammonium salts), and the nature of the stoppering groups (3,5-(t)Bu(2)C(6)H(3)CO(2)- or (t)BuCONH-), can have a significant effect on the rotaxane yield. The X-ray crystal structures of 11 different [2]rotaxanes, a pseudorotaxane, and a two-station molecular shuttle show two distinct types of intercomponent hydrogen bond motifs between the ammonium groups of the organic thread and the fluoride groups of the inorganic ring. The different hydrogen bonding motifs account for the very different rates of dynamics observed for the heterometallic ring on the thread (shuttling slow; rotation fast).

11.
J Am Chem Soc ; 132(45): 16202-11, 2010 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-20973540

RESUMO

In the present work, a new family of pyrene (Py)-substituted phthalocyanines (Pcs), i.e., ZnPc-Py and H(2)Pc-Py, were designed, synthesized, and probed in light of their spectroscopic properties as well as their interactions with single-wall carbon nanotubes (SWNTs). The pyrene units provide the means for non-covalent functionalization of SWNTs via π-π interactions. Such a versatile approach ensures that the electronic properties of SWNTs are not impacted by the chemical modification of the carbon skeleton. The characterization of ZnPc-Py/SWNT and H(2)Pc-Py/SWNT has been performed in suspension and in thin films by means of different spectroscopic and photoelectrochemical techniques. Transient absorption experiments reveal photoinduced electron transfer between the photoactive components. ZnPc-Py/SWNT and H(2)Pc-Py/SWNT have been integrated into photoactive electrodes, revealing stable and reproducible photocurrents with monochromatic internal photoconversion efficiency values for H(2)Pc-Py/SWNT as large as 15 and 23% without and with an applied bias of +0.1 V.


Assuntos
Fontes de Energia Bioelétrica , Indóis/química , Nanotubos de Carbono/química , Pirenos/química , Energia Solar
12.
Chemistry ; 16(1): 114-25, 2010 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-19998436

RESUMO

A novel series of double-decker lanthanide(III) bis(phthalocyaninato)-C(60) dyads [Ln(III)(Pc)(Pc')]-C(60) (M=Sm, Eu, Lu; Pc=phthalocyanine) (1 a-c) have been synthesized from unsymmetrically functionalized heteroleptic sandwich complexes [Ln(III)(Pc)(Pc')] (Ln=Sm, Eu, Lu) 3 a-c and fulleropyrrolidine carboxylic acid 2. The sandwich complexes 3 a-c were obtained by means of a stepwise procedure from unsymmetrically substituted free-base phthalocyanine 5, which was first transformed into the monophthalocyaninato intermediate [Ln(III)(acac)(Pc)] and further reacted with 1,2-dicyanobenzene in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). (1)H NMR spectra of the bis(phthalocyaninato) complexes 3 a-c and dyads 1 a-c were obtained by adding hydrazine hydrate to solutions of the complexes in [D(7)]DMF, a treatment that converts the free radical double-deckers into the protonated species, that is, [Ln(III)(Pc)(Pc')H] and [Ln(III)(Pc)(Pc')H]-C(60). The electronic absorption spectra of 3 a-c and 1 a-c in THF exhibit typical transitions of free-radical sandwich complexes. In the case of dyads 1 a-c, the spectra display the absorption bands of both constituents, but no evidence of ground-state interactions could be appreciated. When the UV/Vis spectra of 3 a-c and 1 a-c were recorded in DMF, typical features of the reduced forms were observed. Cyclic voltammetry studies for 3 a-c and 1 a-c were performed in THF. The electrochemical behavior of dyads 1 a-c is almost the exact sum of the behavior of the components, namely the double-decker [Ln(III)(Pc)(Pc')] and the C(60) fullerene, thus confirming the lack of ground-state interactions between the electroactive units. Photophysical studies on dyads 1 a-c indicate that only after irradiation at 387 nm, which excites both C(60) and [Ln(III)(Pc)(Pc')] components, a photoinduced electron transfer from the [Ln(III)(Pc)(Pc')] to C(60) occurs.


Assuntos
Fulerenos/química , Indóis/síntese química , Elementos da Série dos Lantanídeos/química , Indóis/química , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Estrutura Molecular , Soluções , Estereoisomerismo
13.
J Am Chem Soc ; 130(34): 11503-9, 2008 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-18661981

RESUMO

We describe the functionalization of single-wall carbon nanotubes (SWNTs) with 4-(2-trimethylsilyl)ethynylaniline and the subsequent attachment of a zinc-phthalocyanine (ZnPc) derivative using the reliable Huisgen 1,3-dipolar cycloaddition. The motivation of this study was the preparation of a nanotube-based platform which allows the facile fabrication of more complex functional nanometer-scale structures, such as a SWNT-ZnPc hybrid. The nanotube derivatives described here were fully characterized by a combination of analytical techniques such as Raman, absorption and emission spectroscopy, atomic force and scanning electron microscopy (AFM and SEM), and thermogravimetric analysis (TGA). The SWNT-ZnPc nanoconjugate was also investigated with a series of steady-state and time-resolved spectroscopy experiments, and a photoinduced communication between the two photoactive components (i.e., SWNT and ZnPc) was identified. Such beneficial features lead to monochromatic internal photoconversion efficiencies of 17.3% when the SWNT-ZnPc hybrid material was tested as photoactive material in an ITO photoanode.


Assuntos
Materiais Biocompatíveis/síntese química , Indóis/química , Nanotecnologia/métodos , Nanotubos de Carbono/química , Compostos Organometálicos/química , Teste de Materiais , Microscopia de Força Atômica , Microscopia Eletrônica de Transmissão , Fotoquímica , Análise Espectral Raman , Propriedades de Superfície
14.
Chem Commun (Camb) ; (28): 2950-2, 2007 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-17622441

RESUMO

We report the synthesis, characterization and photophysical features of a new nanometer scale carbon nanostructure, that is, a single-wall carbon nanotube bearing phthalocyanine chromophores.


Assuntos
Indóis/química , Nanotubos de Carbono/química , Microscopia de Força Atômica , Estrutura Molecular , Fotoquímica , Radiossensibilizantes/química
15.
J Am Chem Soc ; 129(16): 5061-8, 2007 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-17397152

RESUMO

HiPco single-walled carbon nanotubes (SWNTs) have been sidewall-functionalized with phthalocyanine addends following two different approaches: a straightforward Prato reaction with N-octylglycine and a formyl-containing phthalocyanine, and a stepwise approach that involves a former Prato cycloaddition to the double bonds of SWNTs using p-formyl benzoic acid followed by esterification of the derivatized nanotubes with an appropriate phthalocyanine molecule. The two materials obtained by these routes comprise different carbon/Pc-addenda ratios, as evidenced by Raman, TGA, and photophysical studies. The occurrence of electron transfer from photoexcited phthalocyanines to the nanotube framework in these ZnPc-SWNT ensembles is observed in transient absorption experiments, which confirm the absorption of the one-electron oxidized ZnPc cation and the concomitant bleaching of the van Hove singularities typical from SWNTs. Charge-separation (i.e., 2.0 x 1010 s(-1)) and charge-recombination (i.e., 1.5 x 106 s(-1)) dynamics reveal a notable stabilization of the radical ion pair product in dimethylformamide.

16.
Cerebrovasc Dis ; 17 Suppl 1: 34-42, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-14694278

RESUMO

BACKGROUND AND OBJECTIVES: Ambulatory blood pressure (BP) monitoring has found some specific clinical indications in the treatment and control of hypertension (HT). As with other target organs exposed to vascular damage dependent on HT, ambulatory BP monitoring can be a useful tool in the prevention of cerebrovascular processes. METHOD: Review of published articles (Medline database) which have investigated the value of continuous recording of BP in cerebrovascular disease (CVD). RESULTS: Research on the BP patterns and its relationship with stroke has been carried out in subjects with no previous history of CVD (cohort studies and in patients with essential HT, differentiating between adults and elderly patients) and patients after a cerebral ischemic event. The study objectives are aimed at determining its prognostic value in the development of silent and symptomatic CVD, and its prognostic significance regarding functional recovery and the differences of the BP patterns according to the different stroke subtypes. CONCLUSIONS: BP monitoring is a useful technique with applications in the control and treatment of the pathological variations of BP in hypertensive patients, with and without a previous history of cerebral ischemia, and mainly in elderly patients, due to the deterioration of the cerebral circulation regulation mechanisms. Clinical research has confirmed the importance of factors related to the circadian rhythm of BP in the primary and secondary prevention of cerebrovascular processes.


Assuntos
Monitorização Ambulatorial da Pressão Arterial , Hipertensão/diagnóstico , Acidente Vascular Cerebral/diagnóstico , Humanos , Acidente Vascular Cerebral/prevenção & controle
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA