Lifetime of singlet oxygen in solution directly determined by laser spectroscopy

Hurst, John R.; McDonald, James H.; Schuster, Gary B.

doi:10.1021/ja00371a065

Cited by 250 publications

(148 citation statements)

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“…It is usually produced by photocatalytic activation of dissolved oxygen on metal oxides such as TiO 2 and ZnO [23,24]. In addition, many other chemicals such as potassium perchromate [25], triphenyl phosphite [26] and ozonide [27] could also generate 1 O 2 . In the current work, an electrochemical system for the cyanide remove with RuO 2 /Ti mesh as the anode, the ACF as cathode and sodium chloride as electrolytes were established.…”

Section: Introductionmentioning

confidence: 99%

Cyanide oxidation by singlet oxygen generated via reaction between H 2 O 2 from cathodic reduction and OCl − from anodic oxidation

Tian¹,

Zeng

et al. 2016

Journal of Colloid and Interface Science

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Section: Introductionmentioning

confidence: 99%

Cyanide oxidation by singlet oxygen generated via reaction between H 2 O 2 from cathodic reduction and OCl − from anodic oxidation

Tian¹,

Zeng

et al. 2016

Journal of Colloid and Interface Science

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“…Several techniques have been used to detect 1 O 2 in condensed phase like 1 O 2 → 3 O 2 NIR phosphorescence [25][26][27][28][29][30][31][32][33], time resolved thermal lens spectroscopy [26,34,35], and the analysis of 1 O 2 specific reaction products [21,29,[36][37][38][39][40][41]. Quantum yields of 1 O 2 production have been investigated for a large number of sensitizers.…”

Section: Introductionmentioning

confidence: 99%

Singlet molecular oxygen photosensitized by Rhodamine dyes: correlation with photophysical properties of the sensitizers

Stracke

Heupel

Thiel

1999

Journal of Photochemistry and Photobiology A: Chemistry

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By measuring its IR phosphorescence the formation of singlet molecular oxygen 1 O 2 photosensitized by rhodamine dyes is directly proved. The 1 O 2 formation rate is compared with that expected from the low probability (≈1%) of intersystem crossing of the photosensitizers. The quantum yield for triplet population and the triplet lifetime of the investigated dyes is measured by using a laser-scanning-microscopy technique. The influence of quenching agents (nitrobenzene and COT) is discussed. It results that the formation of 1 O 2 can be prevented effectively by quenching of the S 1 or T state of the photosensitizer. The influence of the molecular ground-state oxygen 3 O 2 concentration [ 3 O 2 ] is investigated. The presence of the paramagnetic 3 O 2 leads to an increased S 1 →T intersystem crossing rate of the photosensitizers and therefore to a reinforced formation of singlet molecular oxygen. It is found for rhodamine 6G as well as for rose bengal that in air-saturated acetonitrile nearly the half of the excited dye triplets are quenched by molecular oxygen. The 1 O 2 concentration can be significantly reduced by decreasing the 3 O 2 concentration below its air saturated level.

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“…Lifetime measurements of singlet oxygen generated by DMB@OA 2 in H 2 O and D 2 O solutions (5 and 41 µs, respectively; Supporting Information) suggested that singlet oxygen spends most of its lifetime in the aqueous medium. 19 The oxidation studies were performed by irradiating (>500 nm) RB in 1 mM D 2 O solution of 1b@OA 2 under oxygen atmosphere for 10 min (conversion 60-70%). In the alternate method, a buffer solution containing equal amounts of DMB@OA 2 (5 mM) and 1b 2 @OA 2 (1 mM) was irradiated (>310 nm, 4 h).…”

mentioning

confidence: 99%

“…19 The oxidation studies were performed by irradiating (>500 nm) RB in 1 mM D 2 O solution of 1b@OA 2 under oxygen atmosphere for 10 min (conversion 60-70%). In the alternate method, a buffer solution containing equal amounts of DMB@OA 2 (5 mM) and 1b 2 @OA 2 (1 mM) was irradiated (>310 nm, 4 h).…”

mentioning

confidence: 99%

Controlling Photoreactions with Restricted Spaces and Weak Intermolecular Forces: Exquisite Selectivity during Oxidation of Olefins by Singlet Oxygen

et al. 2007

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Addition reactions of singlet oxygen to olefins have been the subject of inquiry since the discovery of singlet oxygen by Kautsky over a century ago. [1][2][3] This report concerns ene reactions yielding allylic hydroperoxides, a process involving addition of singlet oxygen to CdC bonds and simultaneous abstraction of an allylic hydrogen. [4][5][6] When there is more than one set of allylic hydrogens in a given olefin, multiple allylic hydroperoxides are produced. Due to the difficulties in controlling small and highly reactive singlet oxygen, it has not been possible to control the regioselectivity or reactions upon unhindered olefins such as methyl cycloalkenes. 7 A few years ago, we disclosed that preferential abstraction of hydrogen from the methyl group of methyl cycloalkenes could be achieved by preorganizing the olefin through cation-π interactions within zeolites, and this has been confirmed by several other groups. [8][9][10][11][12][13] In this report, we show that the abstraction of methyl hydrogen by singlet oxygen can be eliminated by encapsulating the methyl cycloalkenes within a water-soluble, deep-cavity cavitand, octa acid (OA, Figure 1). 14 This study was prompted by our realization that the methyl group of these guests can be used to anchor and hence orient the olefin within the cavity of OA, and hence supramolecular steric hindrance 15 could be used to prevent singlet oxygen from approaching the methyl group. 16 We have achieved this goal, and the results are presented in this report.Since the host-guest complexation behavior and the product selectivity for ene reaction in 1-methyl cyclopentene (1a), 1-methyl cyclohexene (1b), and 1-methyl cycloheptene (1c) (Scheme 1) are identical, we discuss the results using 1b as the model. Addition of 1 equiv of OA to a turbid aqueous borate buffer (pH ∼8.9) solution containing 1 mM of the olefin resulted in a clear solution, suggesting it had been solubilized by complexation within OA. A 1 H NMR titration study of this complex confirmed a 1:1 ratio of the host and guest (Figure 1), while pulse field gradient spin echo diffusion experiments revealed the complex to be a quaternary, 2:2 capsular complex (Supporting Information). Complexation within the capsule resulted in significant upfield shifting of the guest signals (relative to CDCl 3 ). The most significantly shifted guest signal was from the methyl groups (δ∆ ) -4.3 ppm), indicating that they are each anchored at the narrowest part of each cavity. Upfield shifting and 2D 1 H NMR experiments (Supporting Information) suggested that, of the three sets of allylic hydrogens in the guest, H 3 ( Figure 1) would be most accessible and H 7 (methyl) would be the least accessible to any reagent entering the capsule at the equator. This model suggested that, whereas in chloroform 1b yields three hydroperoxides (Scheme 1), a single hydroperoxide 4b should predominate with 1b included within the OA capsule.We believe that space-filling is primarily behind guest orientation, although weak C-H‚‚‚π interactions 17 ...

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Lifetime of singlet oxygen in solution directly determined by laser spectroscopy

Cited by 250 publications

References 0 publications

Cyanide oxidation by singlet oxygen generated via reaction between H 2 O 2 from cathodic reduction and OCl − from anodic oxidation

Cyanide oxidation by singlet oxygen generated via reaction between H 2 O 2 from cathodic reduction and OCl − from anodic oxidation

Singlet molecular oxygen photosensitized by Rhodamine dyes: correlation with photophysical properties of the sensitizers

Controlling Photoreactions with Restricted Spaces and Weak Intermolecular Forces: Exquisite Selectivity during Oxidation of Olefins by Singlet Oxygen

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