An Electrochemical Study on the Copolymer Formed from Piperazine and Aniline Monomers

[EN] A study on the electrochemical oxidation of piperazine and its electrochemical copolymerization with aniline in acidic medium is presented. It was found that the homopolymerization of piperazine cannot be achieved under electrochemical conditions. A combination of electrochemistry, in situ Fourier transform infrared (FTIR), and ex situ X-ray photoelectron spectroscopy (XPS) spectroscopies was used to characterize both the chemical structure and the redox behavior of an electrochemically synthesized piperazine¿aniline copolymer. The electrochemical sensing properties of the deposited material were also tested against ascorbic acid and dopamine as redox probes.This research was funded by the Spanish Ministerio de Economia y Competitividad and FEDER funds, grant MAT2016-76595-R. The stay of S. Dkhili at the University of Alicante was funded by the Ministry of Higher Education and Scientific Research of Tunisia.Dkhili, S.; López-Bernabeu, S.; Kedir, CN.; Huerta, F.; Montilla, F.; Besbes-Hentati, S.; Morallon, E. (2018). An Electrochemical Study on the Copolymer Formed from Piperazine and Aniline Monomers. Materials. 11(6):1-12. https://doi.org/10.3390/ma11061012S11211

Electrodeposition of 4,4′-di-tert-butylbiphenyl peroxide from the anodic oxidation of p-tert-butylphenol in an alkaline acetonitrile solution

The electrogeneration of pure 4,4′-di-tert-butylbiphenyl peroxide as an electrodeposit could be achieved on a platinum electrode through the anodic oxidation of p-tert butylphenol in the presence of Lutidine, in addition to several soluble oligomers. The electrochemical and theoretical studies have shown that the favored coupling reaction corresponds to the O–O bond, albeit it is generally being considered unstable. Without the strong base, a mixture of trimer, tetramer and pentamer was deposited. The peroxide product presents a different electroactivity to that of the phenolic compound, with the appearance of a redox process involving cathodic and anodic symmetrical peaks at −0.10/0.15 V versus SCE, which indicates the preference of the polymer to adhere onto the electrode surface. The thermal degradation has also been analyzed. Quantum-chemical calculations reveal the reason for the oxygen–oxygen coupling.The authors would like to thank the Tunisian Ministry of Higher Education and Research for its financial support as well as the King Saud University for its funding through the Research Group Project No RGP-VPP-243. They would also like to thank the Spanish Ministry of Economy and Competitiveness for its financial support and the STIs for the ERDF funds (MAT2013-42007-P) and the Generalitat Valenciana (PROMETEO2013/ 038)

Electrochromie du bleu de prusse et detection par effet mirage des echanges d'ions a l'interface bleu de Prusse-electrolyte

SIGLEINIST T 75253 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Electrochemical and spectral studies of auto-assembled arrays of calix[4]arenequinhydrone charge-transfer complex on indium-tin oxide (ITO) glass.

A sensing materiel based on calix[4]arene molecules is electrochemically deposited on ITO electrode coated. A brown film was electrodeposited at a potential Eimp = -1.00 V versus SCE in acetonitrile solvent, however in dichloromethane solvent, a bluish film auto-assembled on the ITO electrode coated at a potential Eimp = -0.65 V versus SCE. Both films are subsequently analyzed by cyclic voltammetry and UV-Vis spectroscopy. This investigation shows that in acetonitrile solvent, the charge-transfer complex, calix[4]arenequinhydrone was formed in electrolytic solution and it was not self-assembled on the ITO electrode. The related UV-Vis spectrum shows a single absorption band towards a wavelength about 350 nm. The optical behaviour of the blue film shows two absorption bands: the first one appears on the first absorption band of the acceptor at 305 nm and the second one in the visible range at 502 nm. The band situated in the visible range correspond to a well-defined charge-transfer band indicating the presence of the charge-transfer complex, the calix[4]arenequinhydrone

Electrochemical synthesis of fluorinated polyanilines

[EN] A set of fluoro-functionalized polyaniline conducting polymers was synthesized by cyclic scanning of the potential from acidic solutions containing aniline and 2-fluoroaniline monomers. The monomer feed ratio was varied to modulate the composition of the synthesized materials. The fluorination level of the copolymers was quantified from X-ray photoelectron spectroscopy. The upper inversion potential of the cyclic scans was proved as a suitable tool to tune the fluorination level, as the reactivity of the growing chains depends strongly on that experimental parameter. We found that terminal fluorinated anilines present a reactivity for homocoupling 5 times lower than for heterocoupling, independently of the limiting potential. Conversely, aniline terminal groups present a reactivity strongly dependent on the limiting potential, favoring the heterocoupling reactions at high inversion potentials. The maximum fluorination level of polyaniline rings achieved is about 75%. (C) 2020 Elsevier Ltd. All rights reserved.The authors wish to thank Generalitat Valenciana (PROMETEO/2018/087) for financial support. Nesrine Saidani would like to thank the Tunisian Ministry of Higher Education and Research for funding her stay at the University of Alicante.Saidani, N.; Morallón, E.; Huerta, F.; Besbes-Hentati, S.; Montilla-Jiménez, F. (2020). Electrochemical synthesis of fluorinated polyanilines. Electrochimica Acta. 348:1-8. https://doi.org/10.1016/j.electacta.2020.136329S1834

Nigella sativa L.: Chemical composition and physicochemical characteristics of lipid fraction

peer reviewedPhysicochemical properties of two Nigella seed varieties, having a Tunisian and Iranian origin, were determined. Physical and chemical analyses of crude oils extracted from the seeds by a cold solvent method were also performed. The following results (on a dry-weight basis) were obtained for Tunisian and Iranian varieties, respectively: protein 26.7% and 22.6%, oil 28.48% and 40.35%, ash 4.86% and 4.41%, and total carbohydrate 40.0% and 32.7%. The major unsaturated fatty acids were linoleic acid (50.3-49.2%), followed by oleic acid (25.0 23.7%), while the main saturated fatty acid was palmitic acid (17.2-18.4%). Myristic, myristoleic, palmitoleic, margaric, margaroleic, stearic, linolenic, arachidic, eicosenoic, behenic and lignoceric acids were also detected. Thermal profiles of both Nigella seed varieties, determined by their DSC melting curves, revealed different thermograms. Sensorial profiles of Tunisian and Iranian seed oils were defined through the CieLab (L-*, a(*), b(*)) colour, oxidative stability by Rancimat test and viscosity. Physicochemical properties of the oils for Tunisian and Iranian varieties, respectively, include: saponification number 211 and 217, peroxide value 5.65 and 4.35, iodine index 120 and 101, and an acidity of 22.7% and 18.6%. Results suggested that Nigella seed oil could deserve further consideration and investigation as a potential new multi-purpose product for industrial, cosmetic and pharmaceutical uses. (c) 2006 Elsevier Ltd. All rights reserved

Spectroelectrochemical study on the copolymerization of o-aminophenol and aminoterephthalic acid

[EN] The electrochemical copolymerization of aminoterephthalic acid (ATA) and o-aminophenol (OAP) was carried out on platinum electrodes in acidic medium. The obtained material, poly (ATA-co-OAP), can be deposited by cyclic scanning of the potential in a wide potential range and shows significant electroactivity. However, it was observed that a copolymer with less over oxidation defects is obtained at inversion potentials where only OAP monomer (and not ATA monomer) is oxidized. The successful incorporation of unoxidized ATA monomers to the growing copolymer chain was confirmed by in situ FTIR spectroscopy and XPS, which suggested a monomer ratio close to 1:2 (ATA:POAP) within the obtained copolymer material. The redox switching of poly(ATA-co-OAP) in acidic medium involves reversible benzenoid-quinoid and phenoxazine-phenoxazone conversions but carboxylic groups do not participate actively on these transformations.Financial support from the Spanish Ministerio de Economía y Competitividad and FEDER funds (MAT2016-76595-R). M. Abidi thanks the Ministry of Higher Education and Scientific Research of Tunisia for funding her stay at the University of AlicanteAbidi, M.; López-Bernabeu, S.; Huerta, F.; Montilla, F.; Besbes-Hentati, S.; Morallón, E. (2017). Spectroelectrochemical study on the copolymerization of o-aminophenol and aminoterephthalic acid. European Polymer Journal. 91:386-395. https://doi.org/10.1016/j.eurpolymj.2017.04.024S3863959

Elaboration of an Imprinted Polymer Film Based on Chitosan Electrodeposition for the Voltammetric Detection of BPA

International audienc

Electrochemical and spectral studies of auto-assembled arrays of calix[4]arenequinhydrone charge-transfer complex on indium–tin oxide (ITO) glass

A sensing materiel based on calix[4]arene molecules is electrochemically deposited on ITO electrode coated. A brown film was electrodeposited at a potential Eimp = -1.00 V versus SCE in acetonitrile solvent, however in dichloromethane solvent, a bluish film auto-assembled on the ITO electrode coated at a potential Eimp = -0.65 V versus SCE. Both films are subsequently analyzed by cyclic voltammetry and UV-Vis spectroscopy. This investigation shows that in acetonitrile solvent, the charge-transfer complex, calix[4]arenequinhydrone was formed in electrolytic solution and it was not self-assembled on the ITO electrode. The related UV-Vis spectrum shows a single absorption band towards a wavelength about 350 nm. The optical behaviour of the blue film shows two absorption bands: the first one appears on the first absorption band of the acceptor at 305 nm and the second one in the visible range at 502 nm. The band situated in the visible range correspond to a well-defined charge-transfer band indicating the presence of the charge-transfer complex, the calix[4]arenequinhydrone