Nanostructure dependence of field-effect mobility in regioregular poly(3-hexylthiophene) thin film field effect transistors

Low polydispersity regioregular polythiophenes with number average molecular weights ranging from 2 to 13 kDa were cast under the same conditions from solution to form a series of field effect transistors (FETs). Tapping mode AFM and grazing incidence small-angle X-ray scattering revealed that in all cases the polymers formed regular nanofibrillar morphologies with the width of nanofibrils proportional to the weight average contour length of polymer chains, indicating that conjugated backbones were oriented perpendicular to the nanofibril axes. FET charge carrier mobilities exhibited exponential dependence on nanofibril width, pointing to the decisive role of extended conjugated pathways in charge transport.     

Performance of SLS/MWCNTs/PANI capacitor electrodes in a physiological electrolyte and in serum

We report a stainless steel/multi walled carbon nanotubes/polyaniline (SLS/MWCNTs/PANI) capacitor electrode capable of operating in a physiological electrolyte and in serum. The specific capacitance of SLS/MWCNTs/PANI reaches 401 F g(-1) in the physiological electrolyte and 326 F g(-1) in serum. The capacity loss at 6.4 μA mm(-2) over 2000 cycles is 10% in the physiological electrolyte and 21% in serum.     

Synthesis of 3,7-diiodo-2,6-di(thiophen-2-yl)benzo[1,2-b:4,5-b']difurans: functional building blocks for the design of new conjugated polymers

3,7-Diiodo-2,6-di(thiophen-2-yl)benzo[1,2-b:4,5-b']difurans are efficiently prepared by an iodine-promoted double cyclization. This new heterocyclic core is readily modified by the attachment of alkyl chains for improved solubility. The use of these compounds for the synthesis of new conjugated polymers is also reported.     

The ultra‐weak Ash conjecture and some particular cases

Ash's functions N _{σ ,k} count the number of k ‐equivalence classes of σ ‐structures of size n . Some conditions on their asymptotic behavior imply the long standing spectrum conjecture. We present a new condition which is equivalent to this conjecture and we discriminate some easy and difficult particular cases. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Interaction between hydrophilic drug and α-cyclodextrins: physico-chemical aspects

The aim of the study was to evaluate if the complexation of a hydrophilic molecule by cyclodextrins is possible. Cyclodextrins (CDs) are hydrophilic cone shaped molecules, which are used as vehicles able to include organic molecules. Because of the presence of hydroxy groups (OH) outside of the molecule, cyclodextrins are not predisposed to include hydrophilic drugs. They are therefore used to improve the solubility of poor water-soluble molecules. In order to evaluate if the complexation of a hydrophilic molecule by cyclodextrins is possible, lyophilized complexes of cysteamine hydrochloride with α-cyclodextrins (α-CD) have been realized. Six analytical techniques (High performance Liquid Chromatography coupled to UV detection, Thin-Layer Chromatography, Fourier Transform Infrared spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC), Mass Spectrometry (SM) and Proton Nuclear Magnetic Resonance (NMR-NOESY spectra)) were used in order to characterize the interaction between the drug and the α-CD. The realization of complex between a cyclodextrin and a water-soluble drug seems feasible. In the case of a hydrophilic molecule, the complexation is not obtained by inclusion of the drug in the cyclodextrin, but by binding to the outside of the cone. This “external complexation” is however sufficient to improve some features of the molecule, such as organoleptic features, and to modifiy measurable parameters (FT-IR, DSC, SM and NMR-NOESY spectra).     

Hybrid material based on 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid and Dawson polyoxoanion [P2Mo18O62]6−. Part II: further characterizations and catalytic oxidation of the NADH coenzyme

In this account, [BMIM]₆P₂Mo₁₈O₆₂ hybrid material was further characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Raman spectroscopy. XRD illustrated that compared to the parent K₆P₂Mo₁₈O₆₂·nH₂O, where 92 % of the structure is crystalline, 84 % of the structure of [BMIM]₆P₂Mo₁₈O₆₂ hybrid material is fine-grain amorphous and only 16 % is crystalline. This was attributed to the replacement of most of the protons and constitution water molecules in K₆P₂Mo₁₈O₆₂·nH₂O by [BMIM]⁺ cations. TEM showed that K₆P₂Mo₁₈O₆₂·nH₂O has uniform and spherical nanoparticles with an average diameter of ~100 nm. However, the hybrid material displayed less uniform morphology with spherical and variously shaped nanoparticles with diameters varying from ~10 to 100 nm. Raman spectroscopy of [BMIM]₆P₂Mo₁₈O₆₂ illustrated that peaks of the Dawson [P₂Mo₁₈O₆₂]^6? unit in [BMIM]₆P₂Mo₁₈O₆₂ hybrid material are not obvious due to the overlap with the peaks of [BMIM]⁺. The latter was related to the large number of [BMIM]⁺ cations surrounding the Dawson unit in the hybrid material. [BMIM]₆P₂Mo₁₈O₆₂ was immobilized on glassy carbon electrode and studied by electrochemistry. Linear sweep voltammetry illustrated that unlike the parent polyoxoanion [P₂Mo₁₈O₆₂]^6? which showed no particular catalytic activity towards the oxidation of the NADH coenzyme, the hybrid material [BMIM]₆P₂Mo₁₈O₆₂ is found to efficiently catalyze the oxidation of the NADH coenzyme at low overpotentials. Amperometry revealed high sensitivities (~1.97 μA?mM^?1?mm^?2) and extended linearity (~9.1 mM) of [BMIM]₆P₂Mo₁₈O₆₂/GC electrode towards the oxidation of the NADH coenzyme.     

Efficient Synthesis of Modified Sulfamides and Cyclosulfamides Containing Phosphonate Moieties

Abstract

The synthesis of two new series of functionalized phosphonates is described. A new entry for the synthesis of 5-phosphonoalkyl cyclosulfamides and bis(phosphonoalkyl) sulfamides starting from dihalogeno bis(amino) sulfone has been developed. These compounds have been synthesized in good yields. Triethylphosphite has been used to introduce the phosphonate moiety into sulfamides and cyclosulfamides via Arbuzov reaction.     

Effect of surfactant and mineral additive on the efficiency of lead-acid battery positive active material

The effect of Sodium tripolyphosphate (STPP) and mineral additive on the performance of the lead-acid battery positive plate has been investigated. The addition of alumina-silicate to the positive paste and STPP to the electrolyte modifies the shape and size of PbO₂ crystals and improves the utilization of the positive active material (PAM). The electrochemical performance of the positive active material was determined using galvanostatic discharge and electrochemical impedance spectroscopy (EIS). The crystal structure and morphology of the PAM (PbO₂) were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The water content of the PAM was calculated using Thermogravimetric analysis (TGA) technique. The results showed that the addition of surfactant and mineral additive changes the morphology and the crystallite size of the PAM. We observe a remarkable improvement of the discharge capacity of the PAM when the surfactant (STPP) is added in the electrolyte. The discharge capacity increases with the decrease of the crystallite size and the charge transfer resistance R_ct of the PAM. This shows that the addition of mineral additive and the surfactant together improves the electrical performance of lead-acid battery.     

Synthesis of heterosteroids. First synthesis of oxa steroid from cholic acid

We wish to report here a new and efficient partial synthesis of 3-oxa-5β-steroid, the first oxa steroid synthesized from cholic acid.