Singlet Oxygen as a Reagent in Organic Synthesis

Zamadar, Matibur; Greer, Alexander

doi:10.1002/9783527628193.ch11

Cited by 32 publications

(29 citation statements)

References 146 publications

(192 reference statements)

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“…5 Table 1 shows the photorelease results at temperatures ranging from −50 °C to 100 °C. The results carried out at lower temperatures are discussed next, followed by those at higher temperatures.…”

Section: Resultsmentioning

confidence: 99%

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Autocatalytic-Assisted Photorelease of a Sensitizer Drug Bound to a Silica Support

et al. 2013

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The photorelease of a sensitizer from a fluorinated silica surface occurs by a reaction of singlet oxygen with the vinyl ether bond linking with scission of a dioxetane intermediate. Irradiation of the released sensitizer generates singlet oxygen, which accelerates the release of more sensitizer via an autocatalytic reaction. Sigmoidal behavior of sensitizer release in n-butanol and n-octanol occurs at the optimal temperature of 20 °C. The photorelease efficiency was reduced at low temperatures, where the sensitizer was retained on the surface due to a long-lived dioxetane with inefficient scission; and also reduced at high temperatures, due to a slower reaction of 1O2 with the vinyl ether bond. Immediate acceleration is a result of released sensitizer being used as a dopant to eliminate the induction step further implicating an autocatalytic mechanism. However, the sigmoidal sensitizer release was not correlated to solvent viscosity, heat or light from the dioxetane decomposition, or to minor O2 solubility enhancements caused by the fluorinated silica. The mechanistic information collected here can be used to help control the pace of drug release; however, it remains to be seen whether an autocatalytic-based drug delivery system has an advantage to those with non-sigmoidal kinetics.

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Section: Resultsmentioning

confidence: 99%

“…The sample was then irradiated with 669-nm laser light, and the yield of photoreleased sensU was measured by UV-VIS (largest of the four Q-band peaks of sensU at λ = 663 nm). b 30 nmol of sensU (concentration = 30 μM) was spiked into solution at time = 0. c The native non-fluorinated silica sensitizer was used (Ref. 5).…”

Section: Figurementioning

confidence: 99%

Autocatalytic-Assisted Photorelease of a Sensitizer Drug Bound to a Silica Support

et al. 2013

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“…21 Diminished singlet oxygen rates would have been expected of entropy-controlled 1 O 2 reactions of the ethene at elevated temperatures. 22-25 …”

Section: Resultsmentioning

confidence: 99%

Fluorine End-Capped Optical Fibers for Photosensitizer Release and Singlet Oxygen Production

et al. 2012

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The usefulness of a fiber optic technique for generating singlet oxygen and releasing the pheophorbide photosensitizer has been increased by the fluorination of the porous Vycor glass tip. Singlet oxygen emerges through the fiber tip with 669-nm light and oxygen, releasing the sensitizer molecules upon a [2 + 2] addition of singlet oxygen with the ethene spacer and scission of a dioxetane intermediate. Switching from a non-fluorinated to a fluorinated glass tip led to a clear reduction of the adsorbtive affinity of the departing sensitizer with improved release into homogeneous toluene solution and bovine tissue. But no difference was found in water since the sensitizer was insoluble. High surface coverage of the nonafluorohexylsilane enhanced the cleavage efficiency by 15% at the ethene site. The fluorosilane groups also caused crowding and seemed to reduce access of 1O2 to the ethene site, which attenuated the total quenching rate constant kT, although there was less wasted 1O2 (from surface physical quenching) at the fluorosilane-coated than the native SiOH silica. The observations support a quenching mechanism that the replacement of the SiOH groups for the fluorosilane C-H and C-F groups enhanced the 1O2 lifetime at the fiber tip interface due to less efficient electronic-to-vibronic energy transfer.

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“…Ene and [4+2]‐cycloaddition reactions are often diagnostic and verify the presence of singlet oxygen (22–24) in solution. Here, we found the formation of 9,10‐anthracene‐9,10‐endoperoxide dipropionate dianion ( 5 ) took place via a [4+2] cycloaddition of singlet oxygen with 9,10‐anthracene dipropionate dianion (0.1–0.2 m , pH = 10, 4 ) (Scheme 4).…”

Section: Resultsmentioning

confidence: 99%

Fiber‐optic Singlet Oxygen [¹O₂ (¹Δ_g)] Generator Device Serving as a Point Selective Sterilizer

Aebisher

Zamadar

Mahendran

et al. 2010

Photochem & Photobiology

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Traditionally, Type II heterogeneous photo-oxidations produce singlet oxygen via external irradiation of a sensitizer and external supply of ground-state oxygen. A potential improvement is reported here. A hollow-core fiber-optic device was developed with an “internal” supply of light and flowing oxygen, and a porous photosensitizer-end capped configuration. Singlet oxygen was delivered through the fiber tip. The singlet oxygen steady-state concentration in the immediate vicinity of the probe tip was ca 20 fM by N-benzoyl-DL-methionine trapping. The device is portable and the singlet oxygen-generating tip is maneuverable, which opened the door to simple disinfectant studies. Complete Escherichia coli inactivation was observed in 2 h when the singlet oxygen sensitizing probe tip was immersed in 0.1 mL aqueous samples of 0.1–4.4 × 107 cells. Photobleaching of the probe tip occurred after ca 12 h of use, requiring baking and sensitizer reloading steps for reuse.

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Singlet Oxygen as a Reagent in Organic Synthesis

Cited by 32 publications

References 146 publications

Autocatalytic-Assisted Photorelease of a Sensitizer Drug Bound to a Silica Support

Autocatalytic-Assisted Photorelease of a Sensitizer Drug Bound to a Silica Support

Fluorine End-Capped Optical Fibers for Photosensitizer Release and Singlet Oxygen Production

Fiber‐optic Singlet Oxygen [¹O₂ (¹Δ_g)] Generator Device Serving as a Point Selective Sterilizer

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Singlet Oxygen as a Reagent in Organic Synthesis

Cited by 32 publications

References 146 publications

Autocatalytic-Assisted Photorelease of a Sensitizer Drug Bound to a Silica Support

Autocatalytic-Assisted Photorelease of a Sensitizer Drug Bound to a Silica Support

Fluorine End-Capped Optical Fibers for Photosensitizer Release and Singlet Oxygen Production

Fiber‐optic Singlet Oxygen [1O2 (1Δg)] Generator Device Serving as a Point Selective Sterilizer

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Product

Resources

About

Fiber‐optic Singlet Oxygen [¹O₂ (¹Δ_g)] Generator Device Serving as a Point Selective Sterilizer