Elucidando os estados de oxidação do nitrogênio através da espectroscopia de absorção de raios-X na borda K do nitrogênio

Nascimento, Gustavo M. do; Temperini, Márcia L. A.

doi:10.1590/s0100-40422006000400033

Cited by 16 publications

(2 citation statements)

References 9 publications

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“…The N K-edge XANES spectroscopy has been successfully employed by our group in the study of oxidation states and interactions in aromatic and/or conjugated systems where the study of many model compounds assists the interpretation of the spectra of more complex materials, such as polymers and ionic liquids. − It was demonstrated, for the first time, the viability to perform N K-edge XANES measurements in solutions using ILs, as solvents, being possible to study the interactions between solute and solvent molecules. For instance, for potassium 2,4-dinitrophenolate, the interaction with the 1-butyl-3-methylimidazolium tetrafluoroborate causes the splitting of the −NO 2 band, and it was possible to observe the conversion of polyaniline in its insulating state (emeraldine base) to its conducting state (emeraldine salt), after dissolution in 1-ethyl-3-methylimidazolium ethylsulfate …”

Section: Introductionmentioning

confidence: 99%

Interionic Interactions in Imidazolic Ionic Liquids Probed by Soft X-ray Absorption Spectroscopy

et al. 2012

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This work investigates pure ionic liquids (ILs) derived from an imidazolium ring with different carbonic chains and halides or bis(trifluoromethanesulfonilimide) (TFSI(-)) as anions, using X-ray absorption near edge spectroscopy (XANES) at different energies (N, S, O, F, and Cl edges) to probe the interionic interactions. XANES data show that the interaction with the anion is weaker when the cation is an imidazolium than when the salt is formed by smaller cations, as lithium, independently of the length of the carbonic chain attached to the imidazolium cation. The results also show that, for all studied ILs, it is not observed any influence of the anion on the XANES spectra of the cation, nor the opposite. 1-Methylimidazolium with Cl(-), a small and strongly coordinating anion, presents in the N K XANES spectrum a splitting of the band corresponding to nitrogen in the imidazolic ring, indicating two different chemical environments. For this cation with TFSI(-), on the contrary, this splitting was not observed, showing that the anion has a weaker interaction with the imidazolic ring, even without a lateral carbonic chain.

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Section: Introductionmentioning

confidence: 99%

Interionic Interactions in Imidazolic Ionic Liquids Probed by Soft X-ray Absorption Spectroscopy

et al. 2012

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“…To circumvent this issue, we considered two methods. First, X-ray photoelectron spectroscopy and soft XAFS electron and fluorescence modes , were used for observing the depth of the ion insertion and reversibility of NN groups. Second, electrochemical impedance measurement was used to calculate the desolvation energy of Na + and Li + ions.…”

Section: Discussionmentioning

confidence: 99%

Application of Porous Coordination Polymer Containing Aromatic Azo Linkers as Cathode-Active Materials in Sodium-Ion Batteries

Shimizu

Mameuda

Toshima

et al. 2022

ACS Appl. Energy Mater.

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Aromatic azo compounds have been reported as organic active materials of sodium-ion and lithium-ion batteries owing to the redox reaction of azo groups (NN) and the introduction of insoluble groups. In this study, we investigated a method to realize both high capacity and good cycle performance of sodium-ion batteries by combining aromatic azo compounds with redox-active atoms insoluble in the electrolyte. Moreover, the metal–organic framework (MOF) CPL-4 ([Cu2(pzdc)2(azpy)], pzdc = pyrazine-2,3-dicarboxylate, azpy = 4,4-azopyridine, pore size: 10 × 6 Å2) was investigated as a cathode-active material for sodium-ion and lithium-ion batteries based on the redox reactions of Cu2+/Cu+ and NN/N–N. In addition to evaluating the battery performance, the reaction mechanism of CPL-4 was elucidated through ex situ X-ray diffraction and operando X-ray absorption fine structure. First, Na+ ions were inserted deeply into the CPL-4 particles, although Li+ ions were stored only on the surface of the CPL-4 particles. Second, during charging/discharging processes, CPL-4 exhibited reversible crystal structural changes and redox reactions of Cu2+/Cu+. The MOFs containing aromatic azo linkers showed interesting redox behavior as cathode-active materials for sodium-ion batteries. These findings will contribute to the design of cathode-active materials for high-performance sodium-ion batteries.

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Dissolution and Doping of Polyaniline Emeraldine Base in Imidazolium Ionic Liquids Investigated by Spectroscopic Techniques

Rodrigues

Nascimento

Santos

2007

Macromol. Rapid Commun.

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Polyaniline is a model molecular system in the study of conductive polymers. Ionic liquids, on the other hand, are becoming more and more a very convenient alternative for conventional organic solvents. The dissolution of polyaniline‐emeraldine base (PANI‐EB) in imidazolium ILs leads to its doping, as indicated by optical and resonance Raman spectroscopies. In this study, it is proposed that the interaction of PANI‐EB and imidazolium ILs involves the specific interaction of the quinoid moiety of the former with the imidazolium ring of the latter, an interpretation that is also based on N K‐edge XANES measurements of neat PANI‐EB, neat ILs, and of their solutions.magnified image

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Elucidando os estados de oxidação do nitrogênio através da espectroscopia de absorção de raios-X na borda K do nitrogênio

Abstract: ®p* transitions, it was possible to correlate the band energy value with the nitrogen oxidation states. An extensive N K XANES spectral database was obtained, thus permitting the elucidation of the nature of different nitrogens present in the intercalated conducting polymers.]]>

Cited by 16 publications

References 9 publications

Interionic Interactions in Imidazolic Ionic Liquids Probed by Soft X-ray Absorption Spectroscopy

Interionic Interactions in Imidazolic Ionic Liquids Probed by Soft X-ray Absorption Spectroscopy

Application of Porous Coordination Polymer Containing Aromatic Azo Linkers as Cathode-Active Materials in Sodium-Ion Batteries

Dissolution and Doping of Polyaniline Emeraldine Base in Imidazolium Ionic Liquids Investigated by Spectroscopic Techniques

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