Search results for "tammet"
showing 10 items of 409 documents
Electrochemical study on (NN)Fe3 (CO)9 ((NN) = 2,3-diazanorbornene) and related compounds. A new example of activation of carbon monoxide replaceme…
1985
Abstract The compound (NN)Fe 3 (CO) 9 ( 1 ) in tetrahydrofuran undergoes two reversible one-electron reduction processes in cyclic voltammetry at the platinum electrode. A rapid electron transfer-catalyzed reaction occurs when 1 is reduced in the presence of L (L = P(OMe) 3 ) and this gives (NN)Fe 3 (CO) 8 L ( 2 ), quantitatively. Only an electron-induced nucleophilic substitution is observed for compound 2 under the same conditions, yielding (NN)Fe 3 (CO) 7 L 2 , which undergoes a similar reaction but with much lower efficiency, to give (NN)Fe 3 (CO) 6 L 3 .
Characterization of poly(N-alkylanilines) by Raman spectroscopy
2007
Abstract Thin films of poly( N -alkylaniline) were synthesized in acidic aqueous solution and in mixtures of aqueous and organic solvents. The polymer films (alkyl = methyl, ethyl, propyl and butyl) were characterized by Raman spectroscopy with the excitation wavelengths of 514.5, 632.8 and 780 nm. The main Raman bands have been characterized for the leucoemeraldine, emeraldine and pernigraniline oxidation states between −0.2 and 0.8 V (vs. Ag|AgCl). This fundamental study shows that the structure of the half-oxidized emeraldine form contains quinoid units, which supports the commonly accepted oxidation and reduction scheme of poly( N -alkylanilines).
Polythiophene S,S dioxides: an investigation on electrochemical doping
2000
Abstract A new strategy for functionalizing oligothiophenes is the transformation of the thienyl sulphurs into the corresponding S,S dioxides, with the effect of lowering the LUMO energy without significantly affecting the HOMO one. From a quinquethiophene S,S dioxide derivative, a polymer (pQTDO) which can be reversibly n-doped at not very negative potentials still maintaining the property of being p-doped at moderate potential values was electrosynthesized. There is, however, a great difference in the ability to store charge of the polymer’s p- and n-doped forms: a great amount of injected negative charge irreversibly modifies the structure of pQTDO.
Electropolymerization of N-methylanthranilic acid and spectroelectrochemical characterization of the formed film
2009
Abstract The electropolymerization of N-methylanthranilic acid (NMAA) is reported in this paper. The monomer is substituted both at ortho- and N-position and, to the best of our knowledge, it has not been previously electropolymerized. Electropolymerization of NMAA was done on glassy carbon and optically transparent (indium) tin oxide electrodes. The obtained films, which are probably of an oligomeric nature (oligoNMMA), were characterized with cyclic voltammetry (CV), in situ UV–vis and Raman spectroscopy, ex situ FTIR spectroscopy and scanning electron microscopy (SEM). Our results show that NMAA can be electropolymerized as thin films in 1.0 M HClO4, but the oxidation and reduction peak …
Electrochromic Performances of Poly(Azure A) Films from Digital Video-Electrochemistry (DVEC)
2020
Poly(Azure A) (PAA) films doped with sodium dodecyl sulfate (SDS) were grown on transparent indium tin oxide (ITO) glass substrates by cyclic voltammetry. The electrochromism of PAA was investigated by digital video-electrochemistry (DVEC). DVEC consists of the acquisition of sequential digital images during the electro-stimulated changes of PAA color. The evolution of red, green, and blue (R, G, B) colors intensity (I) of analyzed pixels provides enough sensitivity to detect changes of some nmol cm−2 of electroactive centers. Besides, the different time evolution of these color intensities can serve to discern among different electroactive centers activated in the polymer. For the first ti…
Electrical properties of γ-crosslinked hydrogels incorporating organic conducting polymers
2007
Abstract Hydrogel composites containing nanoparticles of the protonated emeraldine form of polyaniline (PANI-PE) have been synthesised by γ-irradiation, using either polyvinyl pyrrolidone (PVP) or polyvinyl alcohol (PVA) as steric stabilisers. Swelling behaviour of both hydrogels is reported, together with an electrical characterisation of composites, before and after gel network formation, performed by cyclic voltammetry and impedance spectroscopy. Similarities and differences between the two composite systems are discussed.
The first spiroconjugated TTF- and TCNQ-type molecules: a new class of electroactive systems?
2005
[Structure: see text] Spiroconjugated TTF-type electron donors (13a-c) and TCNQ-type electron acceptors (10, 11) have been prepared from spiroquinone 9. Cyclic voltammetry reveals a relatively weak accepting ability for 10 and 11, and a strong electron-donor character for 13a-c. Whereas the spiroconjugation introduces a destabilization of the LUMO for compounds 9-11, the opposite is observed for compound 13, thus justifying the redox potential values.
Study by EQCM on the voltammetric electrogeneration of poly(neutral red). The effect of the pH and the nature of cations and anions on the electroche…
2003
Generation of poly(neutral red) films has been studied by means of the simultaneous measurements of current–potential and mass–potential curves during cyclic voltammetry (CV) experiments. It has been proved that the presence of molecular oxygen in the solution increases the amount of polymer deposited on the electrode. Otherwise, using the mass/charge ratio it is possible to obtain quantitative information about the electrodeposition by different procedures. It is observed that this ratio decreases when the amount of polymer electrogenerated increases, except when the polymer is not reduced and oxidised after its electrogeneration. The study of poly(neutral red) by CV and quartz crystal mic…
Cyclic voltammetric analysis of pH-dependent complex formation equilibria in anion coordination chemistry
1995
A procedure to analyze pH-dependent complex formation equilibria from cyclic voltammetry is described. Application to adduct formation equilibria between [Fe(CN)(6)](4-) and [Fe(CN)(6)](3-) with different polyammonium receptors is discussed. Extension to the interaction of substrates such as ATP, NAD(+), NADP(+), and carboxylate ions with these receptors by means of competitive interaction with hexacyanoferrate(II) ion is presented.
Electrochemical study on a tricyclic 1,1,1-tricar-bonyl-2,3-1 diazaferrole derivative. II. Activation of carbon monoxide replacement by electron tran…
1986
Etudes, par voltammetrie cyclique, de la reduction electrochimique du complexe de diazaferratricyclodecene, en presence de P(OMe) 3