Electron Transfer Processes in Rotaxanes and Catenanes

Ballardini, Roberto; Gandolfi, Maria Teresa; Balzani, Vincenzo

doi:10.1002/9783527618248.ch44

Cited by 25 publications

(26 citation statements)

References 131 publications

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“…Since the species involved in the quenching processes studied in this paper are ions of opposite charge and may give rise to outer-sphere and inner-sphere precursor complexes (see below), the appropriate kinetic scheme is that shown in Figure 2. 54 In this scheme, kd and k_¿ are the diffusion and dissociation rate constants, kt is either an energy-transfer or electron-transfer rate constant, kb is the rate constant for deactivation (either via back-electron transfer to the ground state or via deactivation of the electronically excited acceptor), kc and k^a re the rate constants for formation or dissociation of an inner-sphere precursor *.3+…”

Section: Discussionmentioning

confidence: 99%

Electron- and energy-transfer processes involving excited states of lanthanide complexes: evidence for inner-sphere and outer-sphere mechanisms

Sabbatini¹,

Perathoner²,

Lattanzi³

et al. 1988

Inorg. Chem.

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Figure 1. Variation, with pH, of the specific rate of reduction of vitamin B12a (hydroxocobalamin) (2.7 X 10-4 M) with formate at 25 °C and µ = 1.0 M (LiC104). Reactions were carried out under N2 in solutions buffered by phthalate, acetate, phosphate, and borate (see Table III).The solid line represents pseudo-first-order rate constants, calculated from eq 4, with [formate], taken as 0.0810 M, as 6.15 X 10-9 M, and KA as 2.95 x 10-4 M; the circles represent experimental values.Attempts to apply this reaction to other formyl species led to results summarized in Table V, which emphasize the unique effectiveness of formate. The other carboxylates would be expected to coordinate with B12a in the same manner as formate and acetate, but the formyl group is generally not properly positioned for migration to Co111. Modest activity is observed in the case of o-formylbenzoic acid, which may react through a somewhat strained transition state I (featuring a seven-membered ring). The complex of glyoxylic acid, HC(=0)C00H, appears to offer a more favorable orientation for internal hydride migration, but reaction here may be inhibited by conversion of this acid by hydration to its gem-diol form (>0=0 + H20 -* >C(OH)2), a transformation that is known to be very nearly complete under our conditions.21Reduction of B12a by ascorbic acid is found to be rapid, but the biphasic profiles observed for this reaction, in conjunction with the known ability of this reductant to undergo both le and 2e oxidations,22 indicate the operation of a different, and more complex, mechanism for this process.Acknowledgment. We thank Aria White for technical assistance.

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Section: Discussionmentioning

confidence: 99%

Electron- and energy-transfer processes involving excited states of lanthanide complexes: evidence for inner-sphere and outer-sphere mechanisms

Sabbatini¹,

Perathoner²,

Lattanzi³

et al. 1988

Inorg. Chem.

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“…These are photoconductivity,3 the large effect of evacuation, and the intensity dependence of for unevacuated coatings. 3 The photoconductivity indicates hole-electron pair production in the electronic bands of the solid hvh + e (4) where h and e represent holes and electrons, respectively. The fates of these electrons and holes occupy much of the subsequent mechanistic considerations.…”

Section: Methodsmentioning

confidence: 99%

Photochemical studies of solid potassium trisoxalatoferrate(III) trihydrate

Spencer¹,

Schmidt²

1971

J. Phys. Chem.

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of iron group elements, ions must be available in quantities of, for instance, about 0.01, 0.1, 0.35, 0.8, and 1.6 ^equiv (or 0.4, 3, 10, 25, and 50 Mg) for bead diameters of 0.2, 0.4, 0.6, 0.8, and 1.0 mm, respectively.(iii) However, the method is inapplicable to ion species, such as polyelectrolytes, which may not be adsorbed by the resin in sufficient quantity to saturate the exchange capacity of the resin. Photochemical Studies of Solid Potassium Trisoxalatoferrate(III) Trihydrate by . E.

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“…In cases 2 and 3, in which k obs is proportional to k fet , determination of k fet requires knowledge of K 1 (case 2) or of K 1 , K et , and k 3 (or more generally K 3 ) (case 3). For reactions between charged species, K 1 and k 3 or K 3 (each functions of the parameters associated with the Coulombic work terms defined in eqs 1 and 2) can be evaluated both theoretically and experimentally. Experimentally, values of K 1 and K et can be obtained by fitting integrated rate expressions to raw kinetic data by means of nonlinear regression techniques in which K and/or k are adjustable parameters .…”

Section: Outer-sphere Electron Transfer Within Stable Donor−acceptor ...mentioning

confidence: 99%

“…However, unlike in the electronic spectra of [CoW 12 O 40 ] 6- , some intervalence charge transfer (i.e., Cu(I) ↔ W(VI) = Cu(II) ↔ W(V)) has been observed in [Cu I W 12 O 40 ]. − …”

Section: One-electron Oxidation Of [Cuiw12o40]7- To [Cuiiw12o40]6-mentioning

confidence: 99%

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Homogeneous-Phase Electron-Transfer Reactions of Polyoxometalates

1998

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ContentsI. Introduction 113 II. Outer-Sphere Electron-Transfer Reactions 115 A. Debye−Smoluchowski and Marcus 115 B. Marcus Equation 116 1. Applications 116 2. Theoretical Calculation of Outer-Sphere Electron-Transfer Rate Constants 117 3. Outer-Sphere Electron Self-Exchange 117 4. The Marcus Cross-Relation 117 C. Ion Pairing between Electrolyte Ions and Electron Donors or Acceptors 118 D. Outer-Sphere Electron Transfer within Stable Donor−Acceptor Complexes 119 III. Electron Self-Exchange between POM Anions 121 A. Keggin Tungstocobaltate Anions 121 B. Keggin and Wells−Dawson Metallophosphate Anions 122 C. Reevaluation of the Reorganization Energy of the [Co III W 12 O 40 ] 5-/[Co II W 12 O 40 ] 6-Couple 125 D. One-Electron Oxidation of [Cu I W 12 O 40 ] 7to [Cu II W 12 O 40 ] 6-129 IV. Oxidation of Organic Electron Donors by POM Anions 129 A. Alkylaromatic Compounds 129 B. Cyclohexadienes 136 C. Organic Acids, Esters, Aldehydes, and Ketones 138 D. Aromatic and Aliphatic Alcohols 142 E. Carbon-Centered Organic Radicals 143 F. Thiols and Organic Sulfides 145 V. Oxidation of Inorganic Electron Donors by POM Anions 148 A. Introduction 148 B. Inorganic Electron Donors 150 C. Hydrogen Sulfide 150 D. Luminescence Quenching of Electronically Excited [Ru(bpy) 3 ] 2+ Cations 152 VI. Reduction of Halogenated Alkanes by Reduced POM Anions 153 A. Carbon Tetrabromide 153 B. Halomethanes 154 C. Carbon Tetrachloride, Halomethanes, and Haloalkanes 155 VII. Reduction of Inorganic Oxidants by Reduced POM Anions 156 157 D. Nitronium Ion 158 E. Peroxodisulfate 159 F. Chlorate and Periodate 159 G. Permanganate 160 VIII. Reduction of Dioxygen by Reduced POM Anions 161 A. Introduction 161 B. Single-Electron Reduction of O 2 161 C. The O 2 /O 2 •-Self-Exchange Reaction 161 D. Reduction of O 2 by Reduced Isopoly-and Heteropolytungstates 162 E. Reduction of O 2 by d-Electron-Containing, Transition-Metal-Substituted Heteropolytungstates 164 F. Reduction of O 2 by Reduced Vanadomolybdophosphates 166 IX. Acknowledgments 167 X. References 167

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Electron Transfer Processes in Rotaxanes and Catenanes

Cited by 25 publications

References 131 publications

Electron- and energy-transfer processes involving excited states of lanthanide complexes: evidence for inner-sphere and outer-sphere mechanisms

Electron- and energy-transfer processes involving excited states of lanthanide complexes: evidence for inner-sphere and outer-sphere mechanisms

Photochemical studies of solid potassium trisoxalatoferrate(III) trihydrate

Homogeneous-Phase Electron-Transfer Reactions of Polyoxometalates

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