Search results for "voltammetry"
showing 10 items of 404 documents
Highly selective detection of Epinephrine at oxidized Single-Wall Carbon Nanohorns modified Screen Printed Electrodes (SPEs)
2014
Oxidized Single-Wall Carbon Nanohorns (o-SWCNHs) were used, for the first time, to assemble chemically modified Screen Printed Electrodes (SPEs) selective towards the electrochemical detection of Epinephrine (Ep), in the presence of Serotonine-5-HT (S-5HT), Dopamine (DA), Nor-Epineprhine (Nor-Ep), Ascorbic Acid (AA), Acetaminophen (Ac) and Uric Acid (UA). The Ep neurotransmitter was detected by using Differential Pulse Voltammetry (DPV), in a wide linear range of concentration (2-2500 μM) with high sensitivity (55.77 A M(-1) cm(-2)), very good reproducibility (RSD% ranging from 2 to 10 for different SPEs), short response time for each measurement (only 2s) and low detection of limit (LOD=0.…
Orthometallation reactions of rhodium compounds containing orthohaloarylphosphines
1988
The reaction of RhCl3·.3H2O with a 3-molar proportion of P(o-ClC6H4)Ph2, (PCCl) at room temperature gives RhCl(PCCl)2 (1), in high yield. Reaction of [Rh(cot)2Cl]2, (cot = cyclooctene), with PCCl, sol12 molar ratio, also gives compound 1. Refluxing of a solution of 1 in 96% ethanol gives RhCl2(PC)(η2-PCCl), [PC (C6H4)PPh2] (2). Complex 1 reacts with CO to give RhClCO(PCCl)2 (3). 31P NMR studies reveal that 1 exhibits a fluxional behaviour in solution in the temperature range −50 to 0 °C. The low temperature spectrum is consistent with the formulation RhCl(η2-PCCl)(η1-PCCl). In cyclic voltammetry complex 2 shows two two-electronic reduction processes, at −0.98 and −1.56 V. Electrochemical …
Synthesis, physicochemical and electrochemical properties of metal–metal bonded ruthenium corrole homodimers
2002
Abstract Two diruthenium(III,III) corrole dimers, [(Et 6 Me 2 Cor)Ru] 2 and [(Me 6 Et 2 Cor)Ru] 2 , where Et 6 Me 2 Cor and Me 6 Et 2 Cor are the 2,3,8,12,17,18-hexaethyl-7,13-dimethylcorrole and 8,12-diethyl-2,3,7,13,17,18-hexamethylcorrole trianions, respectively, were synthesized and characterized as to their spectroscopic and electrochemical properties. They exhibit up to three oxidations and two reductions by cyclic voltammetry in CH 2 Cl 2 or pyridine containing 0.1 M TBAP, almost all of which are electrochemically reversible on the voltammetric and/or thin-layer spectroelectrochemical timescale. The two reductions and the first two oxidations involve one-electron transfer processes w…
Dicopper(II) Metallacyclophanes with Electroswitchable Polymethyl-Substitutedpara-Phenylene Spacers
2013
Double-stranded anionic dinuclear copper(II) metallacyclic complexes of the paracyclophane type [Cu2L2]4- have been prepared by the CuII-mediated self-assembly of different para-phenylenebis(oxamato) bridging ligands with either zero-, one-, or four-electron-donating methyl substituents (L=N,N′-para- phenylenebis(oxamate) (ppba; 1), 2-methyl- N,N′-para-phenylenebis(oxamate) (Meppba; 2), and 2,3,5,6-tetramethyl- N,N′-para-phenylenebis(oxamate) (Me4ppba; 3)). These complexes have been isolated as their tetra-n-butylammonium (1 a-3 a), lithium(I) (1 b-3 b), and tetraphenylphosphonium salts (1 c-3 c). The X-ray crystal structures of 1 a and 3 c show a parallel-displaced π-stacked conformation w…
Single Heteroatom Fine-Tuning of the Emissive Properties in Organoboron Complexes with 7-(Azaheteroaryl)indole Systems
2016
The application of organoboron compounds as light-absorbing or light-emitting species in areas as relevant as organic electronics or biomedicine has motivated the search for new materials which contribute to the progress of those applications. This article reports the synthesis of four-coordinate boron complexes based on the unexplored 7-(azaheteroaryl)indole ligands. An easy synthetic approach has enabled the fine-tuning of the electronic structure of the organoboron species by modifying a heteroaromatic component in the conjugated system. Furthermore, a comprehensive characterization by X-ray diffraction, absorption and emission spectroscopy, both in solution and in the solid state, cycli…
Tuning the electronic properties and the planarity degree in the π-extended TTF series: the prominent role of heteroatoms
2018
The main asset of small molecules for application in organic electronics lies in the tunability of their electronic properties owing to the precise control of their molecular design. Semiconducting properties in organic compounds are for instance closely linked to the molecular planarity degree, including when considering various redox states. Among those species, the π-extended TTF (exTTF: 9,10-bis(1,3-dithiol-2-ylidene)-9,10-dihydroanthracene) presents fascinating redox and structural properties, which have been extensively studied in various fields of organic electronics. Here we show that S-exTTF, a sulfur enriched π-isoelectronic dithieno analogue of pristine exTTF, synthesized through…
A solution study of complex formation between iron(III) and oxalate in dimethylsulphoxide
1991
The complex formation between iron(III) and oxalic acid (ethanedioic acid, H2ox) has been studied by potentiometry in dimethylsulphoxide (dmso) solution. H2ox behaves as a weak diprotic acid in such a solvent, with overall association constants: log βj1=8.551(3) and log βj2=14.242(3) at 25°C and 0.1 Mn-Bu4NClO4. A reliable set of overall stability constants for the iron(III)-oxalato complexes, log β11=13.16(4), log β12=23.66(4) and log β13=30.75(4), have been obtained for the first time under identical conditions. The electrochemical behaviour of such complexes was studied in dmso at a platinum electrode. The coordination ability of oxalate towards iron(III) in dmso and water media is compa…
Oxidative C-N fusion of pyridinyl-substituted porphyrins.
2018
International audience; The mild (electro) chemical oxidation of pyridin-2-ylthio-meso substituted Ni(II) porphyrins affords C-N fused cationic and dicationic pyridinium-based derivatives. These porphyrins are fully characterized and the molecular structure of one of them was confirmed by X-ray crystallography. A mechanism for the intramolecular oxidative C-N coupling is proposed based on theoretical calculations and cyclic voltammetry analyses.
Highly stable and porous porphyrin-based zirconium and hafnium phosphonates – electron crystallography as an important tool for structure elucidation
2018
The Ni-metallated porphyrin-based tetraphosphonic acid (Ni-tetra(4-phosphonophenyl)porphyrin, Ni-H8TPPP) was used for the synthesis of highly porous metal phosphonates containing the tetravalent cations Zr4+ and Hf4+. The compounds were thoroughly characterized regarding their sorption properties towards N2 and H2O as well as thermal and chemical stability. During the synthesis optimization the reaction time could be substantially decreased under stirring from 24 to 3 h in glass vials. M-CAU-30, [M2(Ni-H2TPPP)(OH/F)2]·H2O (M = Zr, Hf) shows exceptionally high specific surface areas for metal phosphonates of aBET = 1070 and 1030 m2 g-1 for Zr- and Hf-CAU-30, respectively, which are very clos…
Identification of lead pigments in nanosamples from ancient paintings and polychromed sculptures using voltammetry of nanoparticles/atomic force micr…
2007
Voltammetry of nanoparticles coupled with atomic force microscopy was used to identify lead pigments in nanosamples proceeding from works of art. Upon mechanical attachment of few nanograms of sample to a graphite plate, well-defined voltammetric responses were obtained for lead orange, lead yellow, lead white, litharge, minium, Naples yellow, and tin-lead yellow, allowing for an unambiguous identification of such pigments. Atomic force images provide evidence for the occurrence of pigment-characteristic reduction processes accompanied by metal deposition on the graphite substrate. Electrochemical parameters are used for pigment identification. Application to the method for identifying lead…