Bibliografías temáticas / N-phenyl nitrones

Literatura académica sobre el tema "N-phenyl nitrones"

Autor: Grafiati

Publicado: 18 de mayo de 2024

Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros

Elija tipo de fuente:

Índice

Artículos de revistas
Tesis
Capítulos de libros
Actas de conferencias

Consulte las listas temáticas de artículos, libros, tesis, actas de conferencias y otras fuentes académicas sobre el tema "N-phenyl nitrones".

Junto a cada fuente en la lista de referencias hay un botón "Agregar a la bibliografía". Pulsa este botón, y generaremos automáticamente la referencia bibliográfica para la obra elegida en el estilo de cita que necesites: APA, MLA, Harvard, Vancouver, Chicago, etc.

También puede descargar el texto completo de la publicación académica en formato pdf y leer en línea su resumen siempre que esté disponible en los metadatos.

Artículos de revistas sobre el tema "N-phenyl nitrones"

Gallis, David E., James A. Warshaw, Bruce J. Acken y DeLanson R. Crist. "Electronic Nature of α-Methoxy, Amino, Cyano, and Mercapto Nitrones". Collection of Czechoslovak Chemical Communications 58, n.º 1 (1993): 125–41. http://dx.doi.org/10.1135/cccc19930125.

Texto completo

Resumen

The electronic nature of various C-substituted nitrones was investigated by IR spectroscopy and 13C NMR as well as MNDO calculations. These include α-methoxy nitrones (imidate N-oxides) RC(OMe)=N(O)t-Bu with R = p-MeOC6H4 (Ia), C6H5 (Ib), p-NO2C6H4 (Ic), and H (Id) and nitrones YCH=N(O)t-Bu with Y = CN (IIIa), n-BuS (IIIb), C6H5CH2NH (IIIc). Upfield 13C shifts of C(α), the iminyl (C=N) carbon, of imidate N-oxides I versus the corresponding imidates are less than the usual upfield shifts of imine N-oxides versus imines, suggesting less buildup of electron density on C(α) in the case of alcoxy nitrones. Charge density and π bond order values from MNDO calculations for C-methoxy-C-phenyl nitrones versus model systems confirm this result and indicate a more localized C=N π bond in nitrones bearing an α-methoxy group. For N-tert-butyl nitrones with an α heteroatom (nitrogen or sulfur), phenyl, or cyano group, C(α) shifts move downfield for π-donating groups and upfield for π-accepting groups. This "reverse substituent effect" as well as C=N stretching frequencies can also be readily explained by C=N π bond containment by lone pair groups. The reported enhanced cycloaddition reactivity of α-alkoxy nitrones and their electrochemical behavior are discussed in terms of HOMO energy levels.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Marano, Stefania, Cristina Minnelli, Lorenzo Ripani, Massimo Marcaccio, Emiliano Laudadio, Giovanna Mobbili, Adolfo Amici, Tatiana Armeni y Pierluigi Stipa. "Insights into the Antioxidant Mechanism of Newly Synthesized Benzoxazinic Nitrones: In Vitro and In Silico Studies with DPPH Model Radical". Antioxidants 10, n.º 8 (29 de julio de 2021): 1224. http://dx.doi.org/10.3390/antiox10081224.

Texto completo

Resumen

Synthetic nitrone spin-traps are being explored as therapeutic agents for the treatment of a wide range of oxidative stress-related pathologies, including but not limited to stroke, cancer, cardiovascular, and neurodegenerative diseases. In this context, increasing efforts are currently being made to the design and synthesis of new nitrone-based compounds with enhanced efficacy. The most researched nitrones are surely the ones related to α-phenyl-tert-butylnitrone (PBN) and 5,5-dimethyl-1-pyrroline N-oxide (DMPO) derivatives, which have shown to possess potent biological activity in many experimental animal models. However, more recently, nitrones with a benzoxazinic structure (3-aryl-2H-benzo[1,4]oxazin-N-oxides) have been demonstrated to have superior antioxidant activity compared to PBN. In this study, two new benzoxazinic nitrones bearing an electron-withdrawing methoxycarbonyl group on the benzo moiety (in para and meta positions respect to the nitronyl function) were synthesized. Their in vitro antioxidant activity was evaluated by two cellular-based assays (inhibition of AAPH-induced human erythrocyte hemolysis and cell death in human retinal pigmented epithelium (ARPE-19) cells) and a chemical approach by means of the α,α-diphenyl-β-picrylhydrazyl (DPPH) scavenging assay, using both electron paramagnetic resonance (EPR) spectroscopy and UV spectrophotometry. A computational approach was also used to investigate their potential primary mechanism of antioxidant action, as well as to rationalize the effect of functionalization on the nitrones reactivity toward DPPH, chosen as model radical in this study. Further insights were also gathered by exploring the nitrone electrochemical properties via cyclic voltammetry and by studying their kinetic behavior by means of EPR spectroscopy. Results showed that the introduction of an electron-withdrawing group in the phenyl moiety in the para position significantly increased the antioxidant capacity of benzoxazinic nitrones both in cell and cell-free systems. From the mechanistic point of view, the calculated results closely matched the experimental findings, strongly suggesting that the H-atom transfer (HAT) is likely to be the primary mechanism in the DPPH quenching.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Chamorro, Beatriz, Iwona E. Głowacka, Joanna Gotkowska, Rafał Gulej, Dimitra Hadjipavlou-Litina, Francisco López-Muñoz, José Marco-Contelles, Dorota G. Piotrowska y María Jesús Oset-Gasque. "Nucleobase-Derived Nitrones: Synthesis and Antioxidant and Neuroprotective Activities in an In Vitro Model of Ischemia–Reperfusion". International Journal of Molecular Sciences 23, n.º 6 (21 de marzo de 2022): 3411. http://dx.doi.org/10.3390/ijms23063411.

Texto completo

Resumen

Herein, we report the synthesis, antioxidant, and neuroprotective properties of some nucleobase-derived nitrones named 9a–i. The neuroprotective properties of nitrones, 9a–i, were measured against an oxygen-glucose-deprivation in vitro ischemia model using human neuroblastoma SH-SY5Y cells. Our results indicate that nitrones, 9a–i, have better neuroprotective and antioxidant properties than α-phenyl-N-tert-butylnitrone (PBN) and are similar to N-acetyl-L-cysteine (NAC), a well-known antioxidant and neuroprotective agent. The nitrones with the highest neuroprotective capacity were those containing purine nucleobases (nitrones 9f, g, B = adenine, theophylline), followed by nitrones with pyrimidine nucleobases with H or F substituents at the C5 position (nitrones 9a, c). All of these possess EC50 values in the range of 1–6 μM and maximal activities higher than 100%. However, the introduction of a methyl substituent (nitrone 9b, B = thymine) or hard halogen substituents such as Br and Cl (nitrones 9d, e, B = 5-Br and 5-Cl uracil, respectively) worsens the neuroprotective activity of the nitrone with uracil as the nucleobase (9a). The effects on overall metabolic cell capacity were confirmed by results on the high anti-necrotic (EC50′s ≈ 2–4 μM) and antioxidant (EC50′s ≈ 0.4–3.5 μM) activities of these compounds on superoxide radical production. In general, all tested nitrones were excellent inhibitors of superoxide radical production in cultured neuroblastoma cells, as well as potent hydroxyl radical scavengers that inhibit in vitro lipid peroxidation, particularly, 9c, f, g, presenting the highest lipoxygenase inhibitory activity among the tested nitrones. Finally, the introduction of two nitrone groups at 9a and 9d (bis-nitronas 9g, i) did not show better neuroprotective effects than their precursor mono-nitrones. These results led us to propose nitrones containing purine (9f, g) and pyrimidine (9a, c) nucleobases as potential therapeutic agents for the treatment of cerebral ischemia and/or neurodegenerative diseases, leading us to further investigate their effects using in vivo models of these pathologies.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Nakajima, Akira, Yuto Ueda, Nobuyuki Endoh, Kunihiko Tajima y Keisuke Makino. "Electron spin resonance analysis of the oxidation reactions of nitrone type spin traps with gold(III) ion". Canadian Journal of Chemistry 83, n.º 8 (1 de agosto de 2005): 1178–84. http://dx.doi.org/10.1139/v05-132.

Texto completo

Resumen

When cyclic nitrones, such as 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), 4-phenyl-5,5-dimethyl-1- pyrroline-N-oxide (PDMPO), and 3,3,5,5-tetramethyl-1-pyrroline-N-oxide (M4PO) were mixed with hydrogen tetrachloro aurate(III), DMPOX (5,5-dimethyl-1-pyrrolid-2-one-N-oxyl) type free radicals appeared with the precipitation of Au(0). The reaction did not proceed with noncyclic nitrones, such as N-tert-butyl-α-phenyl-nitrone (PBN) and α-(4-pyridyl-1-oxide)-N-tert-butyl-nitrone (POBN). The order of the HAuCl4 decrease was DMPO > PDMPO > M4PO. The reaction was depressed by the addition of chloride or hydroxide ions. 1-Hydroxy-5,5-dimethyl-1-pyrrolid-2-one (HDMPN), the precursor of DMPOX, was also oxidized to DMPOX by HAuCl4. Every step of the gold reduction from Au(III) to Au(0) can be used for the oxidation of HDMPN to DMPOX. Based on these and previous results, the reaction was assumed to proceed by the following scheme consisting of a ligand exchange interaction of AuCl4 with >N+O in DMPO, then nucleophilic addition of a water molecule to DMPO, then the stepwise intramolecular transfer of three electrons from DMPO to Au(III), and finally the precipitation of Au(0). Key words: ESR, nitrone, spin traps, DMPO, DMPOX, gold(III) ion.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Rosselin, Marie, Fanny Choteau, Kamal Zéamari, Kevin M. Nash, Amlan Das, Robert Lauricella, Elisabeth Lojou, Béatrice Tuccio, Frederick A. Villamena y Grégory Durand. "Reactivities of Substituted α-Phenyl-N-tert-butyl Nitrones". Journal of Organic Chemistry 79, n.º 14 (3 de julio de 2014): 6615–26. http://dx.doi.org/10.1021/jo501121g.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Kliegel, W., L. Preu, Steven J. Rettig y James Trotter. "Structural studies of organoboron compounds. XXI. Crystal and molecular structures of 3-(phenylmethylidene)-4-methyl-1-phenyl-2,6,7-trioxa-3-azonia-1-boratabicyclo-[2.2.2]octane and N-(4-nitrophenylmethylidene)-5-methyl-2-phenyl-1,3-dioxa-2-bora-5-cyclohexaneamine N-oxide". Canadian Journal of Chemistry 63, n.º 2 (1 de febrero de 1985): 509–15. http://dx.doi.org/10.1139/v85-083.

Texto completo

Resumen

Crystals of 3-(phenylmethylidene)-4-methyl-1-phenyl-2,6,7-trioxa-3-azonia-1-boratabicyclo[2.2.2]octane are orthorhombic, a = 8.0732(7), b = 11.8499(10), c = 31.679(2) Å, Z = 8, space group Pbca, and those of N-(4-nitrophenylmethylidene)-5-methyl-2-phenyl-1,3-dioxa-2-bora-5-cyclohexaneamine N-oxide are monoclinic, a = 6.1873(6), b = 23.206(2), c = 11.3081(11) Å, β = 92.326(5)°, Z = 4, space group P21/n. Both structures were solved by direct methods and were refined by full-matrix least-squares procedures to final R values of 0.041 and 0.036 for 943 and 1679 reflections with I ≥ 3σ(I), respectively. Both compounds are condensation products of bis(hydroxyalkyl)nitrones and phenylboronic acid. 3-(Phenyl-methylidene)-4-methyl-1-phenyl-2,6,7-trioxa-3-azonia-1-boratabicyclo[2.2.2]octane was found to possess a bicyclic structure resulting from intramolecular O → B coordination (O—B = 1.604(7) Å) and is the first such bicyclic boron compound to be structurally characterized. In N-(4-nitrophenylmethylidene)-5-methyl-2-phenyl-1,3-dioxa-2-bora-5-cyclohexaneamine N-oxide, which has weakened nitrone basicity, the O → B interaction does not occur, resulting in a monocyclic system incorporating a trigonal planar boron atom.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Mekheimer, Ramadan A., Khadijah Al-Zaydi, Mahmoud A. A. Ibrahim, Asma Al-Shamary y Kamal Sadek. "Regio- and stereoselective 1,3-dipolar cycloaddition reactions of C-aryl (or hetaryl)-N-phenylnitrones to monosubstituted ylidene malononitriles and 4-benzylidene-2-phenyloxazol-5(4H)-one". Zeitschrift für Naturforschung B 72, n.º 5 (1 de mayo de 2017): 317–26. http://dx.doi.org/10.1515/znb-2016-0263.

Texto completo

Resumen

AbstractThe first example of 1,3-dipolar cycloaddition reactions of C-aryl (or hetaryl)-N-phenylnitrones to monosubstituted ylidene malononitriles and 4-benzylidene-2-phenyl-oxazol-5(4H)-one is described. The reaction of C-(4-(dimethylamino)phenyl)-N-phenyl-nitrone (1a) with 2-(4-substituted-benzylidene)malononitriles 2a, b in dry toluene, in the absence of catalyst, at reflux temperature furnished the novel cycloadducts 2-(3-aryl-2-phenyl-2,3-dihydro-1,2,4-oxadiazol-5-yl)-3-(4-methoxyphenyl)acrylonitriles 3a, b. Refluxing C-aryl (or hetaryl)-N-phenylnitrones 1b–i with 2-(4-methoxy-benzylidene)malononitrile (2a) in dry toluene, in the absence of catalyst, gave the unexpected 2-cyano-3-(4-methoxyphenyl)-acrylamide (5), as the sole product. On the other hand, refluxing 4-benzylidene-2-phenyloxazol-5(4H)-one (7) with an equimolar amount of C-aryl (or hetaryl)-N-phenyl-nitrones 1a–c, f–i in absolute EtOH afforded the previously unknown 5-anilino-4-benzoyl-2-phenyloxazole (10), as the only isolable product. The resulting products were formed with a high degree of regio- and stereoselectivity. Quantum chemical calculations were performed to verify stereoselectivity of the studied reaction. A mechanistic proposal is presented to rationalize the formation of these products.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Kliegel, Wolfgang, Jörg Metge, Steven J. Rettig y James Trotter. "Aromatic aldonitrones of 2-(hydroxyamino)benzyl alcohol and their cyclic isomers. Crystal and molecular structures of a 1-hydroxy-1,2-dihydro-4H-3,1-benzoxazine, a boron chelate, and its parent nitrone ligand". Canadian Journal of Chemistry 76, n.º 4 (1 de abril de 1998): 389–99. http://dx.doi.org/10.1139/v98-023.

Texto completo

Resumen

The synthesis of a series of C-aryl-N-[2-(hydroxymethyl)phenyl]nitrones, 5 (that can also exist under certain conditions as isomeric 1-hydroxy-2-aryl-1,2-dihydro-4H-3,1-benzoxazines, 8), via 2-(hydroxyamino)benzyl alcohol, 4, and their subsequent reactions with oxybis(diphenylborane), (Ph2B)2O, leading to the 5-(arylmethylene)-7,7-diphenyl-6,8-dioxa- 5-azonia-7-borata-5H-6,7,8,9-tetrahydrobenzocyclo- heptenes 6 are described. Crystals of 1-hydroxy-2- (4-methoxyphenyl)- 1,2-dihydro-4H-3,1-benzoxazine, 8b, are monoclinic, a = 9.379(2), b = 10.699(2), c = 12.9392(7) Å, β = 99.916(2)°, Z = 4 (two independent molecules), space group Pa; those of C-[4-(dimethylamino)phenyl]-N-[(2-hydroxymethyl)phenyl]nitrone, 5c, are monoclinic, a = 7.687(1), b = 7.891(1), c = 11.5053(9) Å, β = 92.781(9)°, Z = 2, space group P21; and those of 5-[4-(dimethylamino)phenylmethylene]-7,7-diphenyl-6,8-dioxa-5-azonia-7-borata-5H-6,7,8,9- tetrahydro-benzocycloheptene, 6a, are monoclinic, a = 10.771(1), b = 13.1057(9), c = 16.8724(7) Å, β = 90.005(5)°, Z = 4, space group P21/n. The structures were solved by direct methods and refined by full-matrix least-squares procedures to R(F2) = 0.120 (Rw(F2) = 0.135) for all 3149 reflections (R(F) = 0.071, Rw(F) = 0.063 for 1500 reflections with I >3 σ (I)) for 8b and R(F) = 0.035 and 0.036 (Rw(F) = 0.031 and 0.038) for 1071 and 3594 reflections with I >3 σ (I), respectively, for 5c and 6a. Compound 8b is the first structurally characterized 1-hydroxy-1,2-dihydro-4H-3,1-benzoxazine derivative and 6a features a relatively rare seven-membered boron-containing heterocycle.Key words: C-aryl-N-[2-(hydroxymethyl)phenyl]nitrones, 1-hydroxy-2-aryl-1,2-dihydro-4H-3,1-benzoxazines, organoboron compounds, crystal structures

Los estilos APA, Harvard, Vancouver, ISO, etc.

Suda, Kohji, Toshio Tsujimoto y Masashige Yamauchi. "13C and1H NMR of Arylnitrones. Substituent Effects of α-Phenyl-N-(p-substituted phenyl)nitrones". Bulletin of the Chemical Society of Japan 60, n.º 10 (octubre de 1987): 3607–11. http://dx.doi.org/10.1246/bcsj.60.3607.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Chamorro, Beatriz, David García-Vieira, Daniel Diez-Iriepa, Estíbaliz Garagarza, Mourad Chioua, Dimitra Hadjipavlou-Litina, Francisco López-Muñoz, José Marco-Contelles y María Jesús Oset-Gasque. "Synthesis, Neuroprotection, and Antioxidant Activity of 1,1′-Biphenylnitrones as α-Phenyl-N-tert-butylnitrone Analogues in In Vitro Ischemia Models". Molecules 26, n.º 4 (20 de febrero de 2021): 1127. http://dx.doi.org/10.3390/molecules26041127.

Texto completo

Resumen

Herein, we report the neuroprotective and antioxidant activity of 1,1′-biphenyl nitrones (BPNs) 1–5 as α-phenyl-N-tert-butylnitrone analogues prepared from commercially available [1,1′-biphenyl]-4-carbaldehyde and [1,1′-biphenyl]-4,4′-dicarbaldehyde. The neuroprotection of BPNs1-5 has been measured against oligomycin A/rotenone and in an oxygen–glucose deprivation in vitro ischemia model in human neuroblastoma SH-SY5Y cells. Our results indicate that BPNs 1–5 have better neuroprotective and antioxidant properties than α-phenyl-N-tert-butylnitrone (PBN), and they are quite similar to N-acetyl-L-cysteine (NAC), which is a well-known antioxidant agent. Among the nitrones studied, homo-bis-nitrone BPHBN5, bearing two N-tert-Bu radicals at the nitrone motif, has the best neuroprotective capacity (EC50 = 13.16 ± 1.65 and 25.5 ± 3.93 μM, against the reduction in metabolic activity induced by respiratory chain blockers and oxygen–glucose deprivation in an in vitro ischemia model, respectively) as well as anti-necrotic, anti-apoptotic, and antioxidant activities (EC50 = 11.2 ± 3.94 μM), which were measured by its capacity to reduce superoxide production in human neuroblastoma SH-SY5Y cell cultures, followed by mononitrone BPMN3, with one N-Bn radical, and BPMN2, with only one N-tert-Bu substituent. The antioxidant activity of BPNs1-5 has also been analyzed for their capacity to scavenge hydroxyl free radicals (82% at 100 μM), lipoxygenase inhibition, and the inhibition of lipid peroxidation (68% at 100 μM). Results showed that although the number of nitrone groups improves the neuroprotection profile of these BPNs, the final effect is also dependent on the substitutent that is being incorporated. Thus, BPNs bearing N-tert-Bu and N-Bn groups show better neuroprotective and antioxidant properties than those substituted with Me. All these results led us to propose homo-bis-nitrone BPHBN5 as the most balanced and interesting nitrone based on its neuroprotective capacity in different neuronal models of oxidative stress and in vitro ischemia as well as its antioxidant activity.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Más fuentes

Tesis sobre el tema "N-phenyl nitrones"

Chhetri, Manjit Singh. "N-cyclohenyl, N-phenyl nitrones and their potentiality in isoxazolidine and isoxazoline syntheses". Thesis, University of North Bengal, 2010. http://hdl.handle.net/123456789/1364.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Sharma, Prawin Kumar. "Greener approach to the synthesis of some novel class of isoxazolidine and isoxazoline derivatives using N-methyl and N-phenyl-a-chloro nitrones". Thesis, University of North Bengal, 2016. http://ir.nbu.ac.in/handle/123456789/1884.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Kafley, Saurav. "Synthesis and 1, 3 -dipolar cycloaddition reaction of N-phenyl £ chlora nitrone". Thesis, University of North Bengal, 2010. http://hdl.handle.net/123456789/1419.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Trudeau-Lame, Mary E. "Pharmacokinetics and metabolism of the reactive oxygen scavenger, [alpha]-phenyl-N-tert-butyl nitrone (PBN) and the effects of 3-nitropropionic acid in the Sprague-Dawley rat /". 2002. http://www.consuls.org/record=b2585514.

Texto completo

Resumen

Thesis (M.S.)--Central Connecticut State University, 2002.
Thesis advisor: Michael A. La Fontaine. " ... in partial fulfillment of the requirements for the degree of Master in Natural Science-Chemistry." Includes bibliographical references (leaves 61-66). Also available via the World Wide Web.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Capítulos de libros sobre el tema "N-phenyl nitrones"

Kishida, H., D. Nakae, O. Kusuoka, Y. Kotake, A. Denda, R. A. Floyd y Y. Konishi. "Inhibition of the Development of Hepatocellular Carcinoma by Phenyl N-Tert-Butyl Nitrone in Rats Fed a Choline-Deficient, L-Amino-Acid-Defined Diet". En Oxidative Stress and Digestive Diseases, 165–71. Basel: KARGER, 2001. http://dx.doi.org/10.1159/000062721.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

I. Al-Sulami, Ahlam y Tesfay G. Ashebr. "Novel Synthesis of N–N Azo and Hydrazine Phenyl Ligand Derivatives for Copper(II) Complex Bio-Active Application". En Various Uses of Copper Material [Working Title]. IntechOpen, 2024. http://dx.doi.org/10.5772/intechopen.1004323.

Texto completo

Resumen

Copper(II) complexes possess relatively a broad spectrum of medicinal importance with less toxicity. It is important to note that, in this chapter, copper(II) is selected as chelating central metal atom considering its current reputation to design such bio-active compounds due to its; (i) permits in realizing stable coordination compound, (ii) diverse coordinating capability with oxygen (O), nitrogen (N), sulfur (S) and phosphorus (P) donor ligands, and (iii) exhibits potentially better biological activity. Therefore, the presented chapter offers the up-to-date advancement and future perspective of bio-active copper(II) complexes derived from Schiff base of azo- and phenyl hydrazine-based ligands and their derivatives. To showcase the existing trend of these classes of bio-active compounds, due to the wide depth of the literature, selected seminal compounds exhibiting outstanding biological activity are discussed in detail. Recent studies establish that azo- and phenyl hydrazine-based bio-active copper(II) complexes are among the promising candidates that are expected to replace the conventional antibiotics which are suffering from side effects as well as microbial resistance. However, the collaborative efforts of chemists and biotechnologists are still needed to realize their real world application.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Rajan, Guru Sankar. "Poly(p–benzamide)". En Polymer Data Handbook, 373–82. Oxford University PressNew York, NY, 2009. http://dx.doi.org/10.1093/oso/9780195181012.003.0060.

Texto completo

Resumen

Abstract General Information PBA is the first nonpeptide, synthetic condensation polymer reported to form liquid–crystalline solution. There are several routes to obtain PBA. PBA forms liquid–crystalline solutions because of an inherently extended rigid chain structure produced by a combination of the carbon–nitrogen bond in predominantly trans amide linkages. The molecular conformation is TCTC(T = trans,C = cis), where the internal rotation angles about the N C bond of the amide group and about the virtual bond of N phenyl C are T and C conformations, respectively. The chain of all amide groups is in the head-to-tail order for PBA. Major Applications The dopes of PBA can be utilized for the preparation of films, filaments, fibrids, and coatings. Wet extruded, tough, clear, flexible films can be applied to substrates like glass, ceramics, metals, concrete, and polymeric materials. The high temperature resistance of the polyaramids makes them suitable for asbestos replacement in heat-resistant work wear. PBA has been superseded by poly(p–phenylene terephthalamide).

Los estilos APA, Harvard, Vancouver, ISO, etc.

Actas de conferencias sobre el tema "N-phenyl nitrones"

Yanagisawa, M., M. Kunimoto y T. Homma. "Chemical Analysis of Ultra-Thin DLC Films and Lubricant/DLC Interface Using Plasmonic Sensors". En ASME 2014 Conference on Information Storage and Processing Systems. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/isps2014-6908.

Texto completo

Resumen

The technical potential of a new plasmonic sensor, which can acquire surface-enhanced Raman spectra with high sensitivity by controlling surface plasmons is demonstrated for the chemical analysis of diamond-like carbon (DLC) films, lubricant films, and the DLC/lubricant interface on magnetic disks of sub-nanometer scale. The Raman spectra of thin DLC films and lubricated DLC carbon can be acquired with a high S/N ratio. Raman spectra of lubricated DLC carbon can also be acquired with the high S/N ratio. The wavenumber shift and intensity change of the Raman peaks of the phenyl and hydroxyl groups in the mixed lubricants (ADOH and Z-tetraol) show that the chemical interaction with the DLC surfaces of the phenyl group in the lubricant molecule decreases with increasing nitrogen content, whereas that of the hydroxyl group with the nitrogenated carbon increases. Raman spectra of nitrogenated DLC films are also acquired, the peaks show good agreement with density functional theory calculations. The calculated bonding energy indicates that the hydroxyl groups interact with the nitrogenated carbon.

Los estilos APA, Harvard, Vancouver, ISO, etc.

M. AHMED, Riyadh, Sarah S. ABDUL RAHMAN, Dhefaf H. BADRI, Khawla M. SULTAN, Ismaeel Y. MAJEED y Ghada M. KAMIL. "SYNTHESIS AND CHARACTERISATION OF NEW Co(II), Zn(II) AND Cd(II) COMPLEXES DERIVED FROM OXADIAZOLE LIGAND AND 1,10-PHENANTHROLINE AS Co-LIGAND". En V. International Scientific Congress of Pure, Applied and Technological Sciences. Rimar Academy, 2022. http://dx.doi.org/10.47832/minarcongress5-5.

Texto completo

Resumen

In this work, prepared new ligand namely 5-(2,4—dichloro-phenyl)-1,3,4- oxadiazole-2-(3H)-thion, which was obtained from the 2,4-dichlorobenzoyl chloride with hydrazine, after that reaction with CS2/KOH in methanol. This ligand was reaction with (Co, Zn and Cd) and 1,10-phenanthroline as co-ligand. The ligand and complexes were characterised by IR, UV-Vis, C-H-N, magnetic moment, A.A, Cl content, and m.p.. The data that collected indicate the octahedral geometry around metal ions in all complexes. In IR spectra of complexes, the small shift in ν(C=S), indicating the exocyclic sulfur is not bonding. The ligand is present in thion form, which indicate deprotonated N-H group in complexes and is bonded to Co(II), Zn(II) and Cd(II) through the oxadiazole nitrogen

Los estilos APA, Harvard, Vancouver, ISO, etc.

Khosravi, Zohreh, Alena Hinze y Claus-Peter Klages. "In-situ FTIR-ATR spectroscopic investigations of atmospheric-pressure plasma modification of polyolefin thin films". En 13th International Conference on Plasma Surface Engineering September 10 - 14, 2012, in Garmisch-Partenkirchen, Germany. Linköping University Electronic Press, 2013. http://dx.doi.org/10.3384/wcc2.239-242.

Texto completo

Resumen

Surface treatment of polyolefines by atmospheric-pressure dielectric barrier discharges (DBDs) in virtually oxygen-free nitrogen-containing gases was studied in situ byFourier transform infrared spectroscopy in the attenuated total reflection mode (FTIR-ATR)in order to follow the plasma-chemical generation of chemical functional groups and their further temporal development in the presence of inert or reactive atmospheres.Polyolefin thin films of thicknesses between 50 and 200 nm were prepared directly on ZnS ATR crystals by spin-coating from hot solutions of linear low-density polyethylene (LLDPE), low density polyethylene (LDPE), or polypropylene (PP) in hydrocarbons solvents like xylene or decalin. After the exposure to the afterglows of DBDs in N2 or in mixtures of N2 with H2 or NH3, infrared spectra were taken in situ under inert conditions and after controlled exposure to various reagents, resp., such as water vapor or oxygen. In order to unravel the complex spectra which are generally due to several functional groups with overlapping vibrational bands, exchange reactions with vapor of heavy water (D2O) was applied in order to identify groups which are known to exhibit a rapid H/D exchange like >N=H (imine), -NH2(prim. amine), >NH (sec. amine), -CO-NRH(prim. or sec. amide), using characteristic ratios of wavenumber ratios for corresponding vibrational bands in the deuterated and the protonated moiety.In addition, reactions of the plasma-treated surface with vapors of4-(trifluoromethyl)-benzaldehyde (TFBA) or4-(trifluoromethyl) phenyl isothiocyanate (TPI) were studied by FTIR-ATR in situ. Based on these experiments, tentative assignments of the observed vibration bands to imino, amino, and amido groups are made and interpreted in terms of feasible or probable chemical mechanisms.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Ofrecemos descuentos en todos los planes premium para autores cuyas obras están incluidas en selecciones literarias temáticas. ¡Contáctenos para obtener un código promocional único!