Calculation of electron-transfer rate constants from the properties of charge-transfer absorption bands. The PQ2+,Fe(CN)64- system

Curtis, James A.; Sullivan, B. Patrick; Meyer, Thomas J.

doi:10.1021/ic50214a049

Cited by 65 publications

(33 citation statements)

References 2 publications

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“…We are aware of only two systems where intervalence excitation leads to net, albeit with low quantum yields, transient or permanent changes. In the first, 45 (22) and (23), and therefore…”

Section: Chemical Consequences O F Outer-sphere Intervalence Excitationmentioning

confidence: 99%

Intramolecular Electron Transfer Reactions of Ion Pairs: Thermal, Optical, and Photochemical Pathways

Haim

1985

Comments on Inorganic Chemistry

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“…We are aware of only two systems where intervalence excitation leads to net, albeit with low quantum yields, transient or permanent changes. In the first, 45 (22) and (23), and therefore…”

Section: Chemical Consequences O F Outer-sphere Intervalence Excitationmentioning

confidence: 99%

Intramolecular Electron Transfer Reactions of Ion Pairs: Thermal, Optical, and Photochemical Pathways

Haim

1985

Comments on Inorganic Chemistry

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“…Furthermore, applying the Marcus-Cross relation, rates for the MV2+/ MV +" electron exchange in water have been predicted as 8-I0 ~ and 8.4. 106 M-~s -~ on the basis of measurements of the one-electron reduction of MV 2+ with Fe(CN) 4- [17,18]. Gu and Dong [19] reported on the heterogeneous electron transfer of methyl vioIogen in polyethylenglycol measured by microe[ectrode voltammetry.…”

Section: Introductionmentioning

confidence: 99%

ESR and ENDOR investigations of the degenerate electron exchange reactions of various viologens in solution. Solvent dynamical effects

et al. 2006

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The temperature dependences of the rates of the degenerate electron transfer of various viologens (l,l'-di(hydrocarbyl)-4,4'-bipyridinium salts) are measured in seven different solvents by means of electron spin resonance (ESR) line broadening. Rates vary between 1.7.10 s and 1.1 -l0 9 M-~s -~ at room temperature and clearly show a solvent dynamical effect, which is inferred from the dependence of the rate constants on the longitudinal relaxation time of the solvent. Activation energies ranging from 5.3 to 24.4 kJ mol -l are found. For the first time, hyperfine coupling constants are reported for the radical cations of the hydroxyethyl viologen and the amino viologen based on both continuous-wave ESR and electron-nuclear double resonance spectroscopy. Furthermore, the temperature and the solvent dependence of the hyperfine coupling constants of the methyl viologen radical cation are reported.

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“…The isolated complex is red-colored in the solid state, yet its aqueous solutions are red-purple with an absorption CT band situated at 540 nm [81,82]. It is noteworthy that different research groups realized early that the aforementioned band does not correspond to a viologen radical cation band as it differs in molar absorptivity, energy (radical cation band of methylviologen is centered at λ max = 608 nm), as well as in shape when compared to the latter [83][84][85]. Members of the aforementioned class of CTCs exhibit interesting chromic phenomena and this was observed about 30 years ago by Hammack et al [86].…”

Section: Charge Transfer Complexes Of Viologensmentioning

confidence: 99%

Mono- and Di-Quaternized 4,4′-Bipyridine Derivatives as Key Building Blocks for Medium- and Environment-Responsive Compounds and Materials

Papadakis

2019

Molecules

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Mono-and di-quaternized 4,4 -bipyridine derivatives constitute a family of heterocyclic compounds, which in recent years have been employed in numerous applications. These applications correspond to various disciplines of research and technology. In their majority, two key features of these 4,4 -bipyridine-based derivatives are exploited: their redox activity and their electrochromic aptitude. Contemporary materials and compounds encompassing these skeletons as building blocks are often characterized as multifunctional, as their presence often gives rise to interesting phenomena, e.g., various types of chromism. This research trend is acknowledged, and, in this review article, recent examples of multifunctional chromic materials/compounds of this class are presented. Emphasis is placed on solvent-/medium-and environment-responsive 4,4 -bipyridine derivatives. Two important classes of 4,4 -bipyridine-based products with solvatochromic and/or environment-responsive character are reviewed: viologens (i.e., N,N -disubstituted derivatives) and monoquats (i.e., monosubstituted 4,4 -bipyridine derivatives). The multifunctional nature of these derivatives is analyzed and structure-property relations are discussed in connection to the role of these derivatives in various novel applications.Molecules 2020, 25, 1 2 of 30 recent) underlining the high versatility of this class of compounds [9,10,[12][13][14][15]. Perhaps, the most reviewed subject regarding the viologens is their electrochromism [13,14,16]. Viologens are known to undergo one-electron reductions electrochemically ( Figure 2) yielding colorful radicals i.e., cations that are stable in the absence of O 2 . Yet, their chromism can also be triggered through various stimuli (including light, heat, solvents, presence of various chemical species, pressure, etc.). All these possibilities shape the very versatile "chromic character" of viologens and generally of 4,4 -bipyridine derivatives. Even though this "chromic character" has only recently started gaining more attention and there is an increasing number of research articles emphasizing on the alternative uses of 4,4 -bipyridine derivatives, there are no reviews in this growing area up until now. Such an attempt is presented in this review paper with an emphasis on medium-and environment-responsive compounds and materials based on 4,4 -bipyridine. Primary focus is placed on viologen-involving solvatochromic systems as well as materials and compounds of this class whose chromic behavior is dependent on various environment stimuli. Molecules 2018, 23, x 2 of 30 Figure 2. Schemes depicting (a) the electrochromic cycle (1) and (b) the photochromic cycle of paraquat (A, counter anion). Structure and Properties of Viologens The Strong Electron-Withdrawing Character of ViologensThe strong electron-withdrawing character of viologens has been widely exploited in numerous molecular architectures and materials. Viologens can undergo reversible one-electron reductions forming radical cations (Figure 2a), which are vividly colo...

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Calculation of electron-transfer rate constants from the properties of charge-transfer absorption bands. The PQ2+,Fe(CN)64- system

Cited by 65 publications

References 2 publications

Intramolecular Electron Transfer Reactions of Ion Pairs: Thermal, Optical, and Photochemical Pathways

Intramolecular Electron Transfer Reactions of Ion Pairs: Thermal, Optical, and Photochemical Pathways

ESR and ENDOR investigations of the degenerate electron exchange reactions of various viologens in solution. Solvent dynamical effects

Mono- and Di-Quaternized 4,4′-Bipyridine Derivatives as Key Building Blocks for Medium- and Environment-Responsive Compounds and Materials

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