Persulfoxide and thiadioxirane intermediates in the reaction of sulfides and singlet oxygen

Watanabe, Yasumasa; Kuriki, Nobuo; Ishiguro, Katsuya; Sawaki, Yasuhiko

doi:10.1021/ja00007a048

Cited by 59 publications

(53 citation statements)

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“…The electron-rich and thus nucleophilic sulfur atom of SCN − , 1 , may attack 1 O 2 , 2 , yielding a persulfoxide intermediate, or 1 O 2 may undergo a cyclo-addition with sulfur yielding a thiadioxirane intermediate. Both of these mechanisms have been previously reported, and may yield the key cyanosulfonyl-like species, 3 [15,44]. Attack of 3 by water with concomitant or subsequent ejection of the CN − followed by deprotonation yields the bisulfite anion, 4 .…”

Section: Discussionmentioning

confidence: 78%

Thiocyanate potentiates antimicrobial photodynamic therapy: In situ generation of the sulfur trioxide radical anion by singlet oxygen

Denis

Vecchio

Żądło

et al. 2013

Free Radical Biology and Medicine

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Antimicrobial photodynamic therapy (PDT) is used for the eradication of pathogenic microbial cells and involves the light excitation of dyes in the presence of O2, yielding reactive oxygen species including the hydroxyl radical (•OH) and singlet oxygen (1O2). In order to chemically enhance PDT by the formation of longer-lived radical species, we asked whether thiocyanate (SCN−) could potentiate the methylene blue (MB) and light-mediated killing of the gram-positive Staphylococcus aureus and the gram-negative Escherichia coli. SCN− enhanced PDT (10 μM MB, 5J/cm2 660 nm hv) killing in a concentration-dependent manner of S. aureus by 2.5 log10 to a maximum of 4.2 log10 at 10 mM (P < 0.001) and increased killing of E. coli by 3.6 log10 to a maximum of 5.0 log10 at 10 mM (P < 0.01). We determined that SCN− rapidly depleted O2 from an irradiated MB system, reacting exclusively with 1O2, without quenching the MB excited triplet state. SCN− reacted with 1O2, producing a sulfur trioxide radical anion (a sulfur-centered radical demonstrated by EPR spin trapping). We found that MB-PDT of SCN− in solution produced both sulfite and cyanide anions, and that addition of each of these salts separately enhanced MB-PDT killing of bacteria. We were unable to detect EPR signals of •OH, which, together with kinetic data, strongly suggests that MB, known to produce •OH and 1O2, may, under the conditions used, preferentially form 1O2.

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Section: Discussionmentioning

confidence: 78%

Thiocyanate potentiates antimicrobial photodynamic therapy: In situ generation of the sulfur trioxide radical anion by singlet oxygen

Denis

Vecchio

Żądło

et al. 2013

Free Radical Biology and Medicine

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“…The same phenomenon was also observed in the case of PCN-222/MOF-545. 1a, 4i Based on previous studies 21 on the oxidation of sulfur-containing compounds by singlet oxygen, a reaction mechanism was proposed for the selective photooxidation of CEES, as shown in Fig. 2c.…”

Section: Resultsmentioning

confidence: 99%

“…At the initial stage of the reaction, CEES and 1 O 2 form a persulfoxide intermediate, which has a sufficient lifetime to undergo an intramolecular reaction with a second CEES molecule through nucleophilic addition. 21b This gives rise to an unstable anionic hypervalent intermediate and then breaks down into two sulfoxide products (CEESO). This mechanism would not only explain the selectivity of the photooxidation, but would also account for the induction period in the first cycle as it may correspond to the time it takes for the persulfoxide intermediate to accumulate before it reacts with another CEES molecule, which slows down the initial reaction rate.…”

Section: Resultsmentioning

confidence: 99%

Efficient and selective oxidation of sulfur mustard using singlet oxygen generated by a pyrene-based metal–organic framework

et al. 2016

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A pyrene-based metal-organic framework (MOF) NU-1000 was used as a heterogeneous photocatalyst for the degradation of a sulfur mustard simulant, 2-chloroethyl ethyl sulfide (CEES). Using irradiation from a commercially available and inexpensive ultraviolet (UV) light-emitting diode (LED), singlet oxygen (1O2) is generated by NU-1000 and selectively oxidizes CEES to the nontoxic product 2-chloroethyl ethyl sulfoxide (CEESO). More importantly, this method was tested on the warfare agent sulfur mustard (HD) for the first time using 1O2 and a MOF catalyst, and this method proved to be effective in oxidizing sulfur mustard to nontoxic products without forming the toxic sulfone by-product.

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“…Peroxides of this type, in which all the valence orbitals on X + are filled and no -bond exists, have a structure regarded as a chargetransfer complex of X and singlet oxygen. 82 The [88][89][90] Widely accepted in the intermediacy of persulfoxides, which act as nucleophilic oxidants, 91 but the participation of thiadioxiranes is still only speculative. On the other hand, the intermediates in the 1 O 2 oxidation of phosphines and phosphites have been characterized as cyclic phosphadioxiranes, which have an electrophilic O-transfer activity.…”

Section: Discussionmentioning

confidence: 99%

Novel aspects of carbonyl oxide chemistry

Ishiguro

Nojima

Sawaki

1997

J. Phys. Org. Chem.

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The structural and chemical properties of 1,3-dipolar peroxidic species (X-O-O) such as ozone (X = O) and carbonyl oxides (X = R 2 C) depend significantly on the nature of X. Although cyclic O 3 is thermodynamically unstable, dioxiranes, cyclic isomers of carbonyl oxides, are isolable and have been fully characterized. In contrast to the well known electrophilic nature of ozone, carbonyl oxides usually act as a nucleophilic oxygen transfer agent, but their reactivity could be altered by substituents. It is expected that the chemistry of R 2 C-O 2 species will provide a good starting point for a better understanding of dioxygen complexes (X-O 2 ) with various Xs. Interesting aspects of carbonyl oxide chemistry are discussed, including methods of generation, cyclization to dioxiranes and the nature of their oxygen transfer activities.

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Persulfoxide and thiadioxirane intermediates in the reaction of sulfides and singlet oxygen

Cited by 59 publications

References 1 publication

Thiocyanate potentiates antimicrobial photodynamic therapy: In situ generation of the sulfur trioxide radical anion by singlet oxygen

Thiocyanate potentiates antimicrobial photodynamic therapy: In situ generation of the sulfur trioxide radical anion by singlet oxygen

Efficient and selective oxidation of sulfur mustard using singlet oxygen generated by a pyrene-based metal–organic framework

Novel aspects of carbonyl oxide chemistry

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