Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 8 de 8
Mais filtros

Base de dados
Intervalo de ano de publicação
Chemphyschem ; 14(8): 1670-5, 2013 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-23553876


We show that electron transfer from the perchlorotriphenylmethide anion (PTM(-)) to Y@C82(C2v) is an instantaneous process, suggesting potential applications for using PTM(-) to perform redox titrations of numerous endohedral metallofullerenes. The first representative of a Y@C82-based salt containing the complex cation was prepared by treating Y@C82(C2v) with the [K(+)([18]crown-6)]PTM(-) salt. The synthesis developed involves the use of the [K(+)([18]crown-6)]PTM(-) salt as a provider of both a complex cation and an electron-donating anion that is able to reduce Y@C82 C2v). For the first time, the molar absorption coefficients for neutral and anionic forms of the pure isomer of Y@C82(C2v) were determined in organic solvents with significantly different polarities.

Fulerenos/química , Ítrio/química , Ânions/química , Espectroscopia de Ressonância de Spin Eletrônica , Transporte de Elétrons , Sais/química
Invest Ophthalmol Vis Sci ; 52(11): 8310-5, 2011 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-21948548


PURPOSE: To present the application of a new sensor based on a flexible, highly piezoresistive, nanocomposite, all-organic bilayer (BL) adapted to a contact lens (CL) for non-invasive monitoring intraocular pressure (IOP). METHODS: A prototype of a sensing CL, adapted to a pig eyeball, was tested on different enucleated pig eyes. A rigid, gas-permeable CL was designed as a doughnut shape with a 3-mm hole, where the BL film-based sensor was incorporated. The sensor was a polycarbonate film coated with a polycrystalline layer of the highly piezoresistive molecular conductor ß-(ET)2I3, which can detect deformations caused by pressure changes of 1 mm Hg. The pig eyeballs were subjected to controlled-pressure variations (low-pressure transducer) to register the electrical resistance response of the CL sensor to pressure changes. Similarly, a CL sensor was designed according to the anatomic characteristics of the eye of a volunteer on the research team. RESULTS: A good correlation (r² = 0.99) was demonstrated between the sensing CL electrical response, and IOP (mm Hg) changes in pig eyes, with a sensitivity of 0.4 Ω/mm Hg. A human eye test also showed the high potential of this new sensor (IOP variations caused by eye massage, blinking, and eye movements were registered). CONCLUSIONS: A new nanostructured sensing CL for continuous monitoring of IOP was validated in an in vitro model (porcine eyeball) and in a human eye. This prototype has adequate sensitivity to continuously monitor IOP. This device will be useful for glaucoma diagnosis and treatment.

Lentes de Contato , Glaucoma/diagnóstico , Pressão Intraocular , Monitorização Fisiológica/instrumentação , Nanoestruturas , Desenho de Prótese , Animais , Eletrônica Médica/instrumentação , Humanos , Suínos , Transdutores
Chemphyschem ; 7(4): 920-3, 2006 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-16596615


Temperature has great impact on the structure and size of the linked crystallites of the conducting topmost layer formed at the surface of a polycarbonate film via the reaction BEDT-TTF+IBr [BEDT-TTF=bis(ethylenedithio)tetrathiafulvalene]. We show that fine temperature control permits formation of a semiconducting topmost layer of alpha'-(BEDT-TTF)(2)(I(x)Br(1-x))(3) crystallites with either micro- or nanometre size, a result that opens a route to miniaturized conducting plastic materials.

Membranas Artificiais , Nanoestruturas/química , Polímeros/química , Compostos de Sulfidrila/química , Temperatura , Cristalização , Condutividade Elétrica , Tamanho da Partícula , Propriedades de Superfície
J Phys Chem B ; 109(35): 16705-10, 2005 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-16853126


Both calculations and experimental data, showing the possibility of formation of I3-, I2Cl-, and ICl2- anions through ICl reduction processes, are described in detail. The above processes were used successfully for the preparation of different molecular conductors based on trihalide anions and bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF). The reaction between ICl and BEDT-TTF occurring in a strong polar reaction media (epsilon > or = 34.8 D) results in the formation of novel molecular conductors containing different sets of the I3-, I2Cl-, and ICl2- anions: beta-(BEDT-TTF)2[(I3)0.4(I2Cl)0.6], beta'BEDT-TTF)2[(I2Cl)0.2(ICl2)0.8], and beta' '-('-(BEDT-TTF)2[(I3)0.075(I2Cl)0.150(ICl2). These molecular conductors reveal semiconducting (beta'-phase) as well as metallic (beta- and beta' '-phases) transport properties. It is also shown that in the reaction media with polarity less than 18.4 D only the I3- anion is incorporated in the BEDT-TTF-based molecular crystals. This fact is an unexpected outcome of our study.

J Am Chem Soc ; 125(13): 3948-53, 2003 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-12656630


The low dimensional organic conductor (BEDT-TTF)(2)Br(1.3)I(1.1)Cl(0.6) [BEDT-TTF = bis(ethylenedithio)tertathiafulvalene] is shown to be a unique molecular solid that exists in three crystalline polymorphic forms (alpha'-, alpha' "-, beta' '-phase) and, surprisingly, is able to adopt the same metal-like beta' '-phase at both low (T < 185 K) and high (T > 395 K) temperatures. Several crystals of the alpha'- and alpha' "-phases have been studied using three different techniques: dc-conductivity measurements, ESR spectroscopy, and X-ray diffraction analysis. All these techniques show the existence of the reversible semiconductor <--> metal (alpha' " <--> beta' ') phase transition at both high and low temperatures as well as the alpha' <--> alpha' " phase transition at high temperatures. The phase transitions of these polymorphs are characterized by huge hysteresis and dramatic changes in the transport and magnetic properties. Based on ab initio calculations, it is suggested that dipole-dipole interactions can play a key role in the rich polymorphism of this molecular solid.