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Properties and characterization of conductive polymers
Published in Ze Zhang, Mahmoud Rouabhia, Simon E. Moulton, Conductive Polymers, 2018
David L. Officer, Klaudia Wagner, Pawel Wagner
Spectroelectrochemistry (SEC) is the coupling of a variety of spectroscopic techniques with electrochemical methods, with the most common spectroscopic techniques used for OCPs being optical and vibrational. SEC techniques allow in situ spectroscopic investigations of electrogenerated species. Thus, coupling optical spectroscopy to electrochemistry allows the optical changes of OCPs at a range of different oxidation and reduction potentials to be determined. As discussed in Section 3.3.1 for dextran sulfate–doped PEDOT (Figure 3.11), this allows a correlation between the polymer structure and the electronic nature of the polymer. In a similar manner, IR and Raman measurements at a range of potentials can be used to identify the effects of charge carriers on the polymer structure.
Interfacial Catalysis at Oil/Water Interfaces
Published in Alexander G. Vdlkdv, Interfacial Catalysis, 2002
Despite the lack of a comprehensive understanding of the physical aspects underlying the phenomenological expressions derived previously, they allow characterization of the dynamics of charge transfer employing electrochemical techniques. Conventional techniques such as cyclic voltammetry, chronoamperometry, and a.c. impedance have been complemented by more modern approaches including voltammetry at microinterfaces [2833] and dynamic spectroelectrochemistry [34-43]. All these methodologies can provide valuable insights into the mechanistic aspects of two-phase catalysis involving charged species. As discussed in Section III, electrochemical techniques can provide information on the transfer rate of a phase transfer catalyst by means of Eq. 13. Furthermore, the partitioning of an ionic catalyst can affect the Galvani potential difference as indicated by the Nernst expression, inducing concentration polarization of ionic reactants and substrates (Eqs. 8 and 9).
A cobalt(II) phthalocyanine with indole substituents: formation, characterization and electrocatalytic studies
Published in Journal of Coordination Chemistry, 2019
Vuyelwa Ngwenya, Irvin Noel Booysen, Allen Mambanda
Electronic spectroelectrochemistry was employed to fully delineate the nature of the redox processes I–IV of the metal complex (Figure 2). Inducing a negative overpotential with respect to the halfwave potential of redox process II, distinctive disaggregation of the Q-band was noted accompanied by a progressive redshift of the Q-band from 677 to 711 nm (Figure 2A). The aforementioned UV–Vis spectral changes in conjunction with the formation of a charge transfer band at 472 nm affirm the presence of the Co(I) species in solution [27]. Regeneration experiments were performed to determine how much Co(II) species was regenerated by applying a potential of 0 V which led to the regeneration of only 32% of the Co(II) species. The application of more negative overpotentials corroborated the assignment of redox process I as a CoIPc−2/CoIPc−3 redox couple. More specifically, synonymous of CoIPc−3 species generated in solution, and the intensities of the Q- and B-bands decrease progressively. In addition, a simultaneous redshift in the charge transfer band (to 481 nm) is observed (Figure 2B) [28].
Studying the catecholamine effect on the electronic delocalization of the paramagnetic [Ru(NH3)4(catecholamine)]+ complex through 1H-NMR, theoretical calculations, and resonance Raman
Published in Journal of Coordination Chemistry, 2020
Jacqueline Q. Alves, André L. B. Formiga, Rogéria R. Gonçalves, Roberto S. da Silva
Spectroelectrochemistry data (Figure 5 and Figure S21) provided information that corroborated the cyclic voltammetry results. Full ligand oxidation at 0.5 V (versus Ag/AgCl) caused decrease of the band at 660 nm region attributed to a charge transfer involving the metal ion and catecholamine derivative ligand with consequent appearing of the new band at 520 nm, which was attributed to a charge-transfer process involving the ruthenium and quinone ligand attributed to MLCT band [7, 8] as described in Table 2. The overall process could be explained as described in scheme 1 by analogy of earlier work [2, 3].