Enhancement of the Electrochemical Properties of an Open-Pore Graphite Foam with Electrochemically Reduced Graphene Oxide and Alternating Current Dispersed Platinum Particles

[EN] This paper aimed to improve the electrochemical activity of a pitch-derived open-pore graphite foam (GF) by an electrochemical coating of reduced graphene oxide (RGO) and platinum particles without significantly affecting its 3D-structure. RGO was synthesized using cyclic voltammetry (CV) from a 3 g L(-1)GO and 0.1 M LiClO(4)solution. For the electrodeposition of Pt particles, an alternating current method based on electrochemical impedance spectroscopy (EIS) was used. A sinusoidal voltage from a fixed potential Ei was varied following a selected amplitude (Delta E-ac= +/- 0.35 V) in a frequency range of 8 Hz <= f(i)<= 10Hz, wherei= 500. This method proved its efficiency when compared to the traditional CV by obtaining more highly electroactive coatings in less synthesis time. For samples' characterization, physical measures included permeability, pressure drop, and nitrogen adsorption isotherms. The electrochemical characterization was performed by CV. The surface morphology and chemical composition were examined using field emission electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDX), respectively. RGO improved the electron transfer rate constant of GF, and a more homogeneous coating distribution of reduced size Pt particles was obtained.This research was funded by the Spanish Agencia Estatal de Investigación (AEI) and the European Union (FEDER funds) contracts (MAT2016-77742-C2-1-P, MAT2016-77742-C2-2-P). Financial support of Network E3TECH (CTQ2017-90659-REDT) is acknowledged.Fernández Sáez, J.; Bonastre Cano, JA.; Molina, JM.; Cases, F. (2020). Enhancement of the Electrochemical Properties of an Open-Pore Graphite Foam with Electrochemically Reduced Graphene Oxide and Alternating Current Dispersed Platinum Particles. Coatings. 10(6):1-12. https://doi.org/10.3390/coatings10060551S112106Prieto, R., Louis, E., & Molina, J. M. (2012). Fabrication of mesophase pitch-derived open-pore carbon foams by replication processing. Carbon, 50(5), 1904-1912. doi:10.1016/j.carbon.2011.12.041Molina-Jordá, J. M. (2016). Mesophase pitch-derived graphite foams with selective distribution of TiC nanoparticles for catalytic applications. Carbon, 103, 5-8. doi:10.1016/j.carbon.2016.02.051Lai, J., Nsabimana, A., Luque, R., & Xu, G. (2018). 3D Porous Carbonaceous Electrodes for Electrocatalytic Applications. Joule, 2(1), 76-93. doi:10.1016/j.joule.2017.10.005Morozov, S. V., Novoselov, K. S., Katsnelson, M. I., Schedin, F., Elias, D. C., Jaszczak, J. A., & Geim, A. K. (2008). Giant Intrinsic Carrier Mobilities in Graphene and Its Bilayer. Physical Review Letters, 100(1). doi:10.1103/physrevlett.100.016602Singh, V., Joung, D., Zhai, L., Das, S., Khondaker, S. I., & Seal, S. (2011). Graphene based materials: Past, present and future. Progress in Materials Science, 56(8), 1178-1271. doi:10.1016/j.pmatsci.2011.03.003Zhou, M., Wang, Y., Zhai, Y., Zhai, J., Ren, W., Wang, F., & Dong, S. (2009). Controlled Synthesis of Large-Area and Patterned Electrochemically Reduced Graphene Oxide Films. Chemistry - A European Journal, 15(25), 6116-6120. doi:10.1002/chem.200900596Bonanni, A., & Pumera, M. (2012). Electroactivity of graphene oxide on different substrates. RSC Advances, 2(28), 10575. doi:10.1039/c2ra22079bZhong, M., Song, Y., Li, Y., Ma, C., Zhai, X., Shi, J., … Liu, L. (2012). Effect of reduced graphene oxide on the properties of an activated carbon cloth/polyaniline flexible electrode for supercapacitor application. Journal of Power Sources, 217, 6-12. doi:10.1016/j.jpowsour.2012.05.086Yoo, E., Okata, T., Akita, T., Kohyama, M., Nakamura, J., & Honma, I. (2009). Enhanced Electrocatalytic Activity of Pt Subnanoclusters on Graphene Nanosheet Surface. Nano Letters, 9(6), 2255-2259. doi:10.1021/nl900397tKundu, P., Nethravathi, C., Deshpande, P. A., Rajamathi, M., Madras, G., & Ravishankar, N. (2011). Ultrafast Microwave-Assisted Route to Surfactant-Free Ultrafine Pt Nanoparticles on Graphene: Synergistic Co-reduction Mechanism and High Catalytic Activity. Chemistry of Materials, 23(11), 2772-2780. doi:10.1021/cm200329aXin, Y., Liu, J., Zhou, Y., Liu, W., Gao, J., Xie, Y., … Zou, Z. (2011). Preparation and characterization of Pt supported on graphene with enhanced electrocatalytic activity in fuel cell. Journal of Power Sources, 196(3), 1012-1018. doi:10.1016/j.jpowsour.2010.08.051Zhang, Y., Liu, C., Min, Y., Qi, X., & Ben, X. (2013). The simple preparation of graphene/Pt nanoparticles composites and their electrochemical performance. Journal of Materials Science: Materials in Electronics, 24(9), 3244-3248. doi:10.1007/s10854-013-1235-xProducts: Chemically Modified Graphene Oxidehttps://www.nanoinnova.com/product/chemically-modified-g

Electrochemical study on an activated carbon cloth modified by cyclic voltammetry with polypyrrole/anthraquinone sulfonate and reduced graphene oxide as electrode for energy storage

[EN] This work describes a two-step procedure for the electrochemical coating of reduced graphene oxide (RGO) and polypyrrole anthraquinone sulfonate (PPyAQS) onto an activated carbon cloth (ACC) by cyclic voltammetry (CV). The textile samples were characterized by CV, electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge measurements using a sandwich-type (electrode/separator/electrode) cell designed to operate in three or two-electrode configurations. The presence of RGO onto the ACC surface optimized the electrosynthesis of PPyAQS and reinforced the stability of the polymer with the number of charge/discharge cycles. A retention capacity of 90% after 100 charge-discharge cycles together with an energy density of 7.8¿×¿10¿4¿W¿h¿cm¿2 at a power density of 1.8¿×¿10¿3¿W¿cm¿2 were obtained for the ACC/RGO/PPyAQS sample. The analyses by field emission scanning electron microscopy (FESEM) showed the RGO veils-like and PPyAQS glomerular structures covering the ACC-fibers. The Fourier transform infrared spectroscopy (FTIR) analyses not only detected the presence of PPy and AQS, but also, the changes in the molecular structure of PPyAQS, depending on its oxidation state, as consequence of the redox reactions occurred in the charge/discharge processes in the two-electrode cell.The authors wish to acknowledge to Chemviron Carbon who kindly donated the ZORFLEX® activated carbon fabric. The authors wish to thank the Spanish Agencia Estatal de Investigación de Economía (AEI) and European Union (FEDER funds) for the financial support (contract MAT2016-77742-C2-1-P). Tim Vickers is gratefully acknowledged for help with the English revision. Electron Microscopy Service of the UPV (Universitat Politècnica de València) is gratefully acknowledged for help with FESEM characterization.Fernández Sáez, J.; Bonastre Cano, JA.; Molina Puerto, J.; Cases, F. (2018). Electrochemical study on an activated carbon cloth modified by cyclic voltammetry with polypyrrole/anthraquinone sulfonate and reduced graphene oxide as electrode for energy storage. European Polymer Journal. 103:179-186. https://doi.org/10.1016/j.eurpolymj.2018.04.018S17918610

Understanding the Bond Formation in Hetero Diels-Alder Reactions. An ELF Analysis of the Reaction of Nitroethylene with Dimethylvinylamine

[EN] The bonding evolution in hetero-Diels-Alder (HDA) reactions has been studied by an ELF analysis of the electron reorganization along the HDA reaction between nitroethylene 6 and dimethylvinylamine (DMVA) 9 at the B3LYP/6-31G* level. This cycloaddition takes place along a two-stages one-step mechanism. In the first stage of the reaction, the C1-C6 bond is formed by coupling of two pseudoradical centers positioned at the most electrophilic carbon of nitroethylene 6 and the most nucleophilic center of DMVA 9. In the second stage, the formation of the second O4-C7 bond takes place between a pseudoradical center positioned at the C7 carbon of DMVA and some electron-density provided by the lone pairs of the O4 oxygen. This behavior is in complete agreement with the analyses of the local electrophilicity and nucleophilicity indices, and the spin density of the radical anion of nitroethylene 6 and of the radical cation of DMVA 9. Finally, a relationship between the polar character of the reaction and the egioselectivity is established.We are grateful to the Spanish Government (project CTQ2009-11027/BQU), and the Fondecyt project No. 1100278. Profesor Domingo also thanks Fondecyt by support through the Cooperación InternacionalDomingo Asensi, LR.; Pérez, P.; Aurell Piquer, MJ.; Sáez Cases, JA. (2012). Understanding the Bond Formation in Hetero Diels-Alder Reactions. An ELF Analysis of the Reaction of Nitroethylene with Dimethylvinylamine. Current Organic Chemistry. 16:2343-2351. doi:10.2174/138527212803520263S234323511

Theoretical study on the molecular mechanism of the [5 + 2] vs. [4 + 2] cyclization mediated by Lewis acid in the quinone system

[EN] The thermal and Lewis acid (LA) catalyzed cyclizations of quinone 1 involved in the synthesis of Colombiasin A and Elipsaterosin B have been theoretically studied using DFT methods at the B3LYP/6-311G(d,p) computational level. B3LYP calculations suggest that the formal endo [4 + 2] cycloadduct allowing the synthesis of Colombiasin A is preferentially formed under thermal conditions, while in the presence of the BF3 LA catalyst the formal [5 + 2] cycloadduct is seen, allowing the synthesis of Elipsaterosin B. The BF3 LA catalyst not only accelerates the nucleophilic attack on the C2 carbon of the quinone framework through a more polar C-C bond formation, but also provokes a different electron density rearrangement along the nucleophilic attack favoring the subsequent C-C bond formation at the C4 carbon with the formation of the formal [5 + 2] cycloadduct. ELF bonding analysis along these cyclizations indicates that the C-C single bond formation takes place in the range of 1.91-2.1 angstrom by C-to-C coupling of two pseudoradical centers. Along the formation of the first C2-C9 single bond, these pseudoradical centers appear at one of the most electrophilic and at one of the most nucleophilic centers of quinone 1, C2 and C9 carbons, respectively. Analysis of the Parr functions suggests that although the most favorable electrophilic/nucleophilic interaction is that involving the C2 carbon of quinone and the C12 carbon of the butadiene framework, the intramolecular nature of the cyclization prevents the corresponding reactive channel.This work was supported by the Post-Doctoral fellow FONDECYT Grant 3130359 and Project ICM-P10-003-F CILIS granted by Fondo de Innovacion para la Competitividad del Ministerio de Economia, Fomento y Turismo, Chile.Soto-Delgado, J.; Sáez-Cases, JA.; Tapia, RA.; Domingo, LR. (2013). Theoretical study on the molecular mechanism of the [5 + 2] vs. [4 + 2] cyclization mediated by Lewis acid in the quinone system. Organic and Biomolecular Chemistry. 11(48):8357-8365. https://doi.org/10.1039/c3ob41860jS83578365114

Study of the Stereoselectivity of the Nucleophilic Epoxidation of 3-Hydroxy-2- methylene Esters

The diastereoselectivity of the nucleophilic epoxidation of 3-hydroxy-2-methylene esters has been studied. The 3-hydroxy-2-methylene esters were obtained through a Morita–Baylis–Hillman reaction. The resulting epoxyesters were treated with thiophenol for transformation into 2,3-dihydroxy-2-((phenylthio)methyl), which upon treatment with triphosgene afforded the corresponding cyclic carbonates

Photophysical properties of 5-substituted 2-thiopyrimidines

The aim of the present work is to determine the influence of C5 substitution on the photophysical properties of 2-thiopyrimidines (2-TPyr). For this purpose, 2-thiouracil, 5-t-butyl-2-thiouracil and 2-thiothymine (TU, BTU and TT, respectively) have been selected as target thionucleobases for the experimental studies and, in parallel, for DFT theoretical calculations. The UV spectra displayed by TU, BTU and TT in EtOH were very similar to each other. They showed a maximum around 275 nm and a shoulder at ca. 290 nm. The three 2-TPyr exhibited a strong phosphorescence emission; from the recorded spectra, triplet excited state energies of ca. 307, 304 and 294 kJ mol(-1) were determined for TU, BTU and TT, respectively. Laser excitation at 308 nm gave rise to a broad transient absorption band from 500 nm to 700 nm, which was in principle assigned to triplet-triplet absorption. This assignment was confirmed by energy transfer experiments using biphenyl (E-T = 274 kJ mol(-1)) as an acceptor. The triplet lifetimes were 70 ns, 1.1 mu s and 2.3 mu s, for TU, BTU and TT, respectively. The obtained photophysical data, both in phosphorescence and transient absorption measurements, point to significantly different properties of the TT triplet excited state in spite of the structural similarities. Theoretical calculations at the B3LYP/aug-cc-pVDZ/PCM level agree well with the experimental range of excited state energies and support the pi pi(star) nature of the lowest triplet states.Financial support by the Spanish Government (CTQ2009-13699, CTQ2012-32621, RyC-2007-00476 to V. L.-V., and contracts JAE-Predoc 2011-00740 and JAE-Doc 2010-06204 to V. V.-C. and J. A. S. respectively) and the computing facilities provided by the Theoretical Organic Chemistry group at the Universitat de Valencia (http://utopia.uv.es) are acknowledged.Vendrell Criado, V.; Sáez Cases, JA.; Lhiaubet, VL.; Cuquerella Alabort, MC.; Miranda Alonso, MÁ. (2013). Photophysical properties of 5-substituted 2-thiopyrimidines. Photochemical &amp; Photobiological Sciences Photochemical and Photobiological Sciences. 12(8):1460-1465. doi:10.1039/c3pp50058fS14601465128Kumar, R. (1997). Synthesis and studies on the effect of 2-thiouridine and 4-thiouridine on sugar conformation and RNA duplex stability. Nucleic Acids Research, 25(6), 1272-1280. doi:10.1093/nar/25.6.1272Sintim, H. O., & Kool, E. T. (2006). Enhanced Base Pairing and Replication Efficiency of Thiothymidines, Expanded-size Variants of Thymidine. Journal of the American Chemical Society, 128(2), 396-397. doi:10.1021/ja0562447Favre, A., & Fourrey, J.-L. (1995). Structural Probing of Small Endonucleolytic Ribozymes in Solution Using Thio-Substituted Nucleobases as Intrinsic Photolabels. Accounts of Chemical Research, 28(9), 375-382. doi:10.1021/ar00057a003Cooper, D. S. (2005). Antithyroid Drugs. New England Journal of Medicine, 352(9), 905-917. doi:10.1056/nejmra042972Reader, S. C. J., Carroll, B., Robertson, W. R., & Lambert, A. (1987). Assessment of the biopotency of anti-thyroid drugs using porcine thyroid cells. Biochemical Pharmacology, 36(11), 1825-1828. doi:10.1016/0006-2952(87)90245-0Massey, A., Xu, Y.-Z., & Karran, P. (2001). Photoactivation of DNA thiobases as a potential novel therapeutic option. Current Biology, 11(14), 1142-1146. doi:10.1016/s0960-9822(01)00272-xKuramochi, H., Kobayashi, T., Suzuki, T., & Ichimura, T. (2010). Excited-State Dynamics of 6-Aza-2-thiothymine and 2-Thiothymine: Highly Efficient Intersystem Crossing and Singlet Oxygen Photosensitization. The Journal of Physical Chemistry B, 114(26), 8782-8789. doi:10.1021/jp102067tHarada, Y., Okabe, C., Kobayashi, T., Suzuki, T., Ichimura, T., Nishi, N., & Xu, Y.-Z. (2009). Ultrafast Intersystem Crossing of 4-Thiothymidine in Aqueous Solution. The Journal of Physical Chemistry Letters, 1(2), 480-484. doi:10.1021/jz900276xFavre, A., Saintomé, C., Fourrey, J.-L., Clivio, P., & Laugâa, P. (1998). Thionucleobases as intrinsic photoaffinity probes of nucleic acid structure and nucleic acid-protein interactions. Journal of Photochemistry and Photobiology B: Biology, 42(2), 109-124. doi:10.1016/s1011-1344(97)00116-4Coleman, R. S., & Siedlecki, J. M. (1992). Synthesis of a 4-thio-2’-deoxyuridine containing oligonucleotide. Development of the thiocarbonyl group as a linker element. Journal of the American Chemical Society, 114(23), 9229-9230. doi:10.1021/ja00049a089Hafner, M., Landthaler, M., Burger, L., Khorshid, M., Hausser, J., Berninger, P., … Tuschl, T. (2010). Transcriptome-wide Identification of RNA-Binding Protein and MicroRNA Target Sites by PAR-CLIP. Cell, 141(1), 129-141. doi:10.1016/j.cell.2010.03.009Basnak, I., Balkan, A., Coe, P. L., & Walker, R. T. (1994). The Synthesis of Some 5-Substituted and 5,6-Disubstituted 2′-Deoxyuridines. Nucleosides and Nucleotides, 13(1-3), 177-196. doi:10.1080/15257779408013234Becke, A. D. (1988). Density-functional exchange-energy approximation with correct asymptotic behavior. Physical Review A, 38(6), 3098-3100. doi:10.1103/physreva.38.3098Lee, C., Yang, W., & Parr, R. G. (1988). Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density. Physical Review B, 37(2), 785-789. doi:10.1103/physrevb.37.785Yanai, T., Tew, D. P., & Handy, N. C. (2004). A new hybrid exchange–correlation functional using the Coulomb-attenuating method (CAM-B3LYP). Chemical Physics Letters, 393(1-3), 51-57. doi:10.1016/j.cplett.2004.06.011Chai, J.-D., & Head-Gordon, M. (2008). Systematic optimization of long-range corrected hybrid density functionals. The Journal of Chemical Physics, 128(8), 084106. doi:10.1063/1.2834918Zhao, Y., & Truhlar, D. G. (2007). The M06 suite of density functionals for main group thermochemistry, thermochemical kinetics, noncovalent interactions, excited states, and transition elements: two new functionals and systematic testing of four M06-class functionals and 12 other functionals. Theoretical Chemistry Accounts, 120(1-3), 215-241. doi:10.1007/s00214-007-0310-xAdamo, C., & Barone, V. (1999). Toward reliable density functional methods without adjustable parameters: The PBE0 model. The Journal of Chemical Physics, 110(13), 6158-6170. doi:10.1063/1.478522Ditchfield, R., Hehre, W. J., & Pople, J. A. (1971). Self‐Consistent Molecular‐Orbital Methods. IX. An Extended Gaussian‐Type Basis for Molecular‐Orbital Studies of Organic Molecules. The Journal of Chemical Physics, 54(2), 724-728. doi:10.1063/1.1674902Dunning, T. H. (1989). Gaussian basis sets for use in correlated molecular calculations. I. The atoms boron through neon and hydrogen. The Journal of Chemical Physics, 90(2), 1007-1023. doi:10.1063/1.456153Bauernschmitt, R., & Ahlrichs, R. (1996). Treatment of electronic excitations within the adiabatic approximation of time dependent density functional theory. Chemical Physics Letters, 256(4-5), 454-464. doi:10.1016/0009-2614(96)00440-xCasida, M. E., Jamorski, C., Casida, K. C., & Salahub, D. R. (1998). Molecular excitation energies to high-lying bound states from time-dependent density-functional response theory: Characterization and correction of the time-dependent local density approximation ionization threshold. The Journal of Chemical Physics, 108(11), 4439-4449. doi:10.1063/1.475855Stratmann, R. E., Scuseria, G. E., & Frisch, M. J. (1998). An efficient implementation of time-dependent density-functional theory for the calculation of excitation energies of large molecules. The Journal of Chemical Physics, 109(19), 8218-8224. doi:10.1063/1.477483Van Caillie, C., & Amos, R. D. (1999). Geometric derivatives of excitation energies using SCF and DFT. Chemical Physics Letters, 308(3-4), 249-255. doi:10.1016/s0009-2614(99)00646-6Van Caillie, C., & Amos, R. D. (2000). Geometric derivatives of density functional theory excitation energies using gradient-corrected functionals. Chemical Physics Letters, 317(1-2), 159-164. doi:10.1016/s0009-2614(99)01346-9Furche, F., & Ahlrichs, R. (2002). Adiabatic time-dependent density functional methods for excited state properties. The Journal of Chemical Physics, 117(16), 7433-7447. doi:10.1063/1.1508368Scalmani, G., Frisch, M. J., Mennucci, B., Tomasi, J., Cammi, R., & Barone, V. (2006). Geometries and properties of excited states in the gas phase and in solution: Theory and application of a time-dependent density functional theory polarizable continuum model. The Journal of Chemical Physics, 124(9), 094107. doi:10.1063/1.2173258Cossi, M., Scalmani, G., Rega, N., & Barone, V. (2002). New developments in the polarizable continuum model for quantum mechanical and classical calculations on molecules in solution. The Journal of Chemical Physics, 117(1), 43-54. doi:10.1063/1.1480445Barone, V., Cossi, M., & Tomasi, J. (1997). A new definition of cavities for the computation of solvation free energies by the polarizable continuum model. The Journal of Chemical Physics, 107(8), 3210-3221. doi:10.1063/1.47467

Study on the specific capacitance of an activated carbon cloth modified with reduced graphene oxide and polyaniline by cyclic voltammetry

This work describes a two-step process for the electrochemical coating of reduced graphene oxide (RGO) and polyaniline (PANI) onto an activated carbon cloth (ACC) by cyclic voltammetry (CV). The fact that the two syntheses are carried out independently of each other, makes it possible to select the experimental conditions for each one and to study the electrochemical response of RGO, PANI, and PANI onto RGO (RGOPANI), separately. Thus, by modifying the potential limits of the aniline-polymerization reaction, it was possible to observe the influence of RGO and the maximum amount of PANI that the carbon cloth can receive in terms of proper electrochemical response. Electrochemical properties were characterized by CV, galvanostatic charge-discharge curves (using three or two-electrodes symmetric cell configurations) and electrochemical impedance spectroscopy (EIS). A maximum improvement of 25%, 56% and 61% over the initial specific capacitance of ACC (about 129 F g−1) were obtained for RGO, PANI and RGOPANI coatings, respectively. Good cycling stability retaining 83% of the initial capacitance, after 1000 cycles stability test, was obtained for RGOPANI sample. Promising results of energy and power densities were also achieved. In the analyses by Fourier transform infrared spectroscopy (FTIR), the PANI-bands could be clearly identified which is indicative of a significant presence of PANI. Field emission scanning electron microscopy (FESEM) showed the morphology of RGO, PANI and RGOPANI onto the ACC fibers. These analyses helped to explain the electrochemical results.The authors wish to acknowledge to Chemviron Carbon who kindly donated the ZORFLEX (R) activated carbon fabric. The authors wish to thank the Spanish Agenda Estatal de Investigacion (AEI) and European Union (FEDER funds) for the financial support (contract MAT2016-77742-C2-1-P). Tim Vickers is gratefully acknowledged for help with the English revision.Fernández Sáez, J.; Bonastre Cano, JA.; Molina Puerto, J.; Del Río García, AI.; Cases Iborra, FJ. (2017). Study on the specific capacitance of an activated carbon cloth modified with reduced graphene oxide and polyaniline by cyclic voltammetry. European Polymer Journal. 92:194-203. doi:10.1016/j.eurpolymj.2017.04.044S1942039

Chemical, electrical and electrochemical characterization of hybrid organic/inorganic polypyrrole/PW12O403- coating deposited on polyester fabrics

A study of the stability of conducting fabrics of polyester (PES) coated with polypyrrole/PW12O403¿ (organic/inorganic hybrid material) in different pH solutions (1, 7, 13) has been done. Washing tests were also done in views of its possible application in electronic textiles such as antistatic clothing. X-ray photoelectron spectroscopy (XPS) studies have been done to quantify the amount of counter ion that remains in the polymer matrix and determine the doping ratio (N+/N) after the different tests. Scanning electron microscopy (SEM) was also used to observe morphological differences after the different tests. Surface resistivity changes were measured by means of electrochemical impedance spectroscopy (EIS). Scanning electrochemical microscopy (SECM) was employed to measure changes in electroactivity after the different tests. Higher pHs caused a decrease of the doping ratio (N+/N), the loss of part of the counter ions and the decrease of its conducting and electrocatalytic properties. The stability in acid media and neutral media and after the washing test was good. Only at pH 13 the loss of the counter ion was widespread and there was a decrease of its conducting and catalytic properties; although the fabrics continued acting mainly as a conducting material.Authors thank the Spanish Ministerio de Ciencia y Tecnologia, European Union Funds (FEDER) (contract CTM2007-66570-C02-02) and Universitat Politecnica de Valencia (Programa de apoyo a la investigacion y desarrollo de la UPV (PAID-05-08)) for the financial support. J. Molina is grateful to the Conselleria d'Educacio (Generalitat Valenciana) for the FPI fellowship. A.I. del Rio is grateful to the Spanish Ministerio de Ciencia y Tecnologia for the FPI fellowship.Molina Puerto, J.; Fernández Sáez, J.; Del Río García, AI.; Bonastre Cano, JA.; Cases Iborra, FJ. (2011). Chemical, electrical and electrochemical characterization of hybrid organic/inorganic polypyrrole/PW12O403- coating deposited on polyester fabrics. Applied Surface Science. 257:10056-10064. doi:10.1016/j.apsusc.2011.06.140S100561006425

Electrochemical synthesis of polyaniline on conducting fabrics of polyester covered with polypyrrole/PW12O403-. Chemical and electrochemical characterization

Polyaniline (Pani) has been electrochemically polymerized on conducting fabrics of polyester covered with polypyrrole/PW 12O 40 3-, obtaining a double conducting polymer layer. Electrochemical synthesis was performed by potentiostatic synthesis at 1 V. The chemical characterization of the material before and after Pani polymerization was performed by means of X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray (EDX) and Fourier transform infrared spectroscopy (FTIR). The morphology of the coatings was observed employing scanning electron microscopy (SEM). The electrochemical characterization was performed by cyclic voltammetry (CV) and scanning electrochemical microscopy (SECM). It has been demonstrated that scan rate is an important parameter that influences the response obtained when characterizing conducting fabrics by CV. High scan rates do not allow the observation of redox peaks. However if lower scan rates are employed its apparition has been reported. The electrochemical deposit of polyaniline enhances the electroactivity of the material as it has been demonstrated by CV. SECM measurements showed local response with positive feedback (electroactive material) for the samples in open circuit conditions. XPS analysis also showed a higher doping level (N +/N), consistent with higher material electroactivity. © 2011 Elsevier B.V.Authors thank to the Spanish Ministerio de Ciencia y Tecnologia and European Union Funds (FEDER) (contract CTM2007-66570-C02-02 and CTM2010-18842-C02-02) and Universidad Politecnica de Valencia (Primeros Proyectos de Investigacion (PAID-06-10)) for the financial support. j. Molina is grateful to the Conselleria d'Educacio (Generalitat Valenciana) for the FPI fellowship. A.I. del Rio is grateful to the Spanish Ministerio de Ciencia y Tecnologia for the FPI fellowship.Molina Puerto, J.; Fernández Sáez, J.; Del Río García, AI.; Bonastre Cano, JA.; Cases Iborra, FJ. (2011). Electrochemical synthesis of polyaniline on conducting fabrics of polyester covered with polypyrrole/PW12O403-. Chemical and electrochemical characterization. Synthetic Metals. 161(11-12):953-963. doi:10.1016/j.synthmet.2011.02.029S95396316111-1

Formation of Pyrazol-1,3,4-Thiadiazoles through 1,3-Dipolar Cycloadditions of 3-Thioxo-[1,2,4]-Triazepin-5-one with Nitrilimines: An Experimental and Computational study

In this work the results of experimental and computational study of the title compounds and some ancillary compounds are reported. Two bicyclic pyrazol-1,3,4-thiadiazole derivatives were synthesized by reaction between 6-dimethylaminomethylene-3-thioxo-[1,2,4]- triazepin-5-one 1 and several nitrilimines 2a-f to give corresponding spirocycloadducts 3a-f, which undergo a rapid rearrangement leading to the new bicyclic compounds, 4a-f and 5a-f. These obtained bicyclic products were characterized by 1H and 13C NMR spectroscopy and finally by X-ray crystallography. Theoretical calculations have been carried out using DFT methods to rationalize the formation of the two new bicyclic compounds. Two reaction types are involved in the formation of the compounds 4a-f and 5a-f. The first one is a 1,3-dipolar cycloaddition reaction between 1 acting as dipolarophile and 2a-f as dipoles. The results indicate that the cycloaddition between 1 and 2g, as model of 2a-c, takes place via a high asynchronous bond-formation process. The regioselectivity obtained from the calculations is in complete agreement with the formation of the unique spirocycloadducts 3a-f. The second reaction leading to the formation of the final products is a domino process that is initiated by the quick and irreversible cleavage in a catalytic acid environment of triazepenic ring