Charge-transfer interactions of excited molecules with inorganic anions: the role of spin-orbit coupling in controlling net electron transfer

Treinin, A.; Loeff, I.; Hurley, John K.; Linschitz, Henry

doi:10.1016/0009-2614(83)80569-7

Cited by 31 publications

(23 citation statements)

References 22 publications

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“…2). The greater spin−orbit coupling constant of Br − compared with Cl − promotes the intersystem crossing associated with quenching (34). At >100 mM halides, ternary exciplexes form, promoting RHS formation (Eqs.…”

Section: Photochemical Generation Of Rhs Rhs Formation Via Halide Scmentioning

confidence: 99%

Halogen radicals contribute to photooxidation in coastal and estuarine waters

Parker

Mitch

2016

Proc. Natl. Acad. Sci. U.S.A.

195

220

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Although halogen radicals are recognized to form as products of hydroxyl radical (• OH) scavenging by halides, their contribution to the phototransformation of marine organic compounds has received little attention. We demonstrate that, relative to freshwater conditions, seawater halides can increase photodegradation rates of domoic acid, a marine algal toxin, and dimethyl sulfide, a volatile precursor to cloud condensation nuclei, up to fivefold. Using synthetic seawater solutions, we show that the increased photodegradation is specific to dissolved organic matter (DOM) and halides, rather than other seawater salt constituents (e.g., carbonates) or photoactive species (e.g., iron and nitrate). Experiments in synthetic and natural coastal and estuarine water samples demonstrate that the halide-specific increase in photodegradation could be attributed to photochemically generated halogen radicals rather than other photoproduced reactive intermediates [e. OH-independent pathway. Our results indicate that halogen radicals significantly contribute to the phototransformation of algal products in coastal or estuarine surface waters.halogen radicals | photochemistry | domoic acid | dimethyl sulfide | dissolved organic matter R esearch on the photochemical transformation of organic compounds in seawater has focused on freshwater-relevant pathways, including direct photolysis and dissolved organic matter (DOM)-sensitized indirect photodegradation by excited triplet state DOM ( 3 DOM*) or reactive oxygen species [e.g., hydroxyl radical ( • OH)] (1). High halide concentrations, the key characteristic distinguishing seawater from freshwater, are the predominant sink for• OH in seawater, with Br − scavenging ∼93% (Eq. 1) (2), resulting in an ∼40-fold reduction in• OH concentrations.• OH + BrThe role of the resultant Br• , as well as other radical reactive halogen species (RHS) (e.g., Cl ), in seawater photochemistry has received little attention. Here we evaluate the contribution of RHS, a family of photooxidants specific to seawater, to the photodegradation of important marine products for two reasons. Unlike diffusion-limited• OH rate constants, RHS rate constants with organic molecules span orders of magnitude (3), such that conversion of • OH to RHS focuses oxidation on more reactive molecules relative to bulk DOM. Secondly, direct halide oxidation by 3 DOM*, previously demonstrated using model triplet sensitizers (4, 5), may provide a seawater-specific,• OH-independent RHS production pathway that could increase overall radical generation rates.We investigated the importance of RHS for photooxidation of dienes and thioethers. Dienes occur in biomolecules (e.g., fatty acids) and in the marine algal toxin (6, 7), domoic acid (Fig. 1A, ii), where the diene contributes to toxicity (8). During summer 2015, a large bloom of the marine diatom Pseudo-nitzschia, extending from central California to Alaska, led to significant concern regarding the production of domoic acid, a potent neurotoxin (9). Consumption of mollusks and fish...

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Section: Photochemical Generation Of Rhs Rhs Formation Via Halide Scmentioning

confidence: 99%

Halogen radicals contribute to photooxidation in coastal and estuarine waters

Parker

Mitch

2016

Proc. Natl. Acad. Sci. U.S.A.

195

220

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“…17 Such effects are known as external and internal heavy atom effects, respectively 18 and have been intensively investigated both in monomolecular [19][20][21] and bimolecular systems. [22][23][24][25][26] The aim of this paper is to investigate the heavy atom effects in the bianthryl and dibromobianthryl molecules by means of fluorescence and transient absorption techniques. The solvent polarity influence on charge transfer intersystem crossing rate constant will be also discussed on the basis of fluorescence measurements and by comparison with model calculations based on Marcus theory for electron transfer probability.…”

Section: Introductionmentioning

confidence: 99%

Investigations of the heavy atom effect occurring in bianthryl and 10,10′-dibromobianthryl. Fluorescence, cyclovoltamperometric and actinometric studiesDedicated to Professor Dr Z. R. Grabowski and Professor Dr J. Wirz on the occasions of their 75th and 60th birthdays.

Mac

Danel

Kizior

et al. 2002

Phys. Chem. Chem. Phys.

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“…if the frequency of internal motions is determined by 11 Ho 11~A = 10 2 -10 3 cm-1 • We shall return to this point below. To proceed further it is convenient to choose the following set of irreducible tensor operators as a basis in the Liouville space (15) where…”

Section: The Kinetic Equation For the Averaged Operatormentioning

confidence: 99%

Relaxation of Electronic Angular Momentum in Kramers Systems with Strong Spin-Orbit Coupling. 1. Atomic Radicals in Solution*

1992

Zeitschrift Für Physikalische Chemie

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A theoretical treatment of electron angular momentum relaxation in atoms induced by electric field fluctuations in a liquid solvent cage is presented. It is shown that in the case of weak interaction between solvent shell and a "target" atom the rate of transitions between the components of a Kramers doublet decreases sharply with the increase of adiabatic splitting between the terms of atomic fine-structure. An analytical expression for the rate of solvent induced angular momentum relaxation in the ground state of halogen atoms is obtained. This process is shown to be independent of the strength of spin-orbit coupling in the system. Oer Artikel gibt eine theoretische Behandlung der Relaxation des elektronischen Orehimpulses von Atomen in flussiger Lasung auf Grund von Fluktuationen des elektrischen Feldes im Lasungsmittelkiifig. Es wird gezeigt, daB im Falle schwacher Wechselwirkung zwischen Solvatsphiire und dem solvatisierten Atom die Ubergangsraten zwischen den Komponenten eines Kramers-Oubletts mit zunehmender adiabatischer Aufspaltung zwischen den atomaren Feinstrukturtennen sehr stark abnimmt. Fur die Ratenkonstante der Lasungsmittel-induzierten Relaxation des elektronischen Orehimpulses von Halo-. genatomen wird ein analytischer Ausdruck abgeleitet. Oas Ergebnis zeigt. daB hier die Relaxationsrate unabhiingig ist von der Stiirke der Spin-Bahn-Kopplung.

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Charge-transfer interactions of excited molecules with inorganic anions: the role of spin-orbit coupling in controlling net electron transfer

Cited by 31 publications

References 22 publications

Halogen radicals contribute to photooxidation in coastal and estuarine waters

Halogen radicals contribute to photooxidation in coastal and estuarine waters

Investigations of the heavy atom effect occurring in bianthryl and 10,10′-dibromobianthryl. Fluorescence, cyclovoltamperometric and actinometric studiesDedicated to Professor Dr Z. R. Grabowski and Professor Dr J. Wirz on the occasions of their 75th and 60th birthdays.

Relaxation of Electronic Angular Momentum in Kramers Systems with Strong Spin-Orbit Coupling. 1. Atomic Radicals in Solution*

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