Hydrazines: new charge-transfer physical quenchers of singlet oxygen

Clennan, Edward L.; Noe, L. J.; Szneler, Edward; Wen, T.C.

doi:10.1021/ja00169a013

Cited by 64 publications

(48 citation statements)

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“…From the comparison of the traces, it is clear that in general, there is a poor singlet oxygen production for all the systems in which CDs are present, in agreement with our previous results . This low singlet oxygen production can be attributable both to the 1 O 2 quenching process by OH moieties of ethanol and cyclodextrins , and to the PS triplet state quenching caused by the presence of Chl a aggregated forms, as evidenced by the Chl a triplet spectra shown in the inset of Fig. .…”

Section: Resultssupporting

confidence: 89%

Identification of Ros Produced by Photodynamic Activity of Chlorophyll/Cyclodextrin Inclusion Complexes

Cellamare

Fini

Agostiano

et al. 2012

Photochem & Photobiology

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Photodynamic therapy (PDT) is a way of treating malignant tumors and hyperproliferative diseases. It is based on the use of photosensitizer, herein the chlorophyll a (chl a), and a light of an appropriate wavelength. The interaction of the photosensitizer (PS) with the light produces reactive oxygen species (ROS), powerful oxidizing agents, which cause critical damage to the tissue. To solubilize chl a in aqueous solution and to obtain it as monomer, we have used cyclodextrins, carriers which are able to interact with the pigment and form the inclusion complex. The aim of this study is to examine which types of ROS are formed by Chl a/cyclodextrin complexes in phosphate buffered solution and cell culture medium, using specific molecules, called primary acceptors, which react selectively with the reactive species. In fact the changes of the absorption and the emission spectra of these molecules after the illumination of the PS provide information on the specific ROS formation. The (1) O2 formation has been tested using chemical methods based on the use of Uric Acid (UA), 9,10-diphenilanthracene (DPA) and Singlet oxygen sensor green (SOSG) and by direct detection of Singlet Oxygen ((1) O2 ) luminescence decay at 1270 nm. Moreover, 2,7-dichlorofluorescin and ferricytochrome c (Cyt Fe(3+) ) have been used to detect the formation of hydrogen peroxide and superoxide radical anion, which reduces Fe(3+) of the ferricytochrome to Fe(2+) , respectively.

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Section: Resultssupporting

confidence: 89%

Identification of Ros Produced by Photodynamic Activity of Chlorophyll/Cyclodextrin Inclusion Complexes

Cellamare

Fini

Agostiano

et al. 2012

Photochem & Photobiology

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“…Furthermore, a saddle point which connects 7 and 4 has been located, but it is too high (27.3 kcal mol −1 ) for ring closure at experimentally relevant conditions. Interaction of singlet oxygen with the nitrogen atoms of 1 is likely lead to a physical quenching process, as has been detected with hydrazines , but such a quenching channel that includes a charge‐transfer interaction was not modeled.…”

Section: Resultsmentioning

confidence: 99%

Theoretical Study of the Reaction Formalhydrazone with Singlet Oxygen. Fragmentation of the C=N Bond, Ene Reaction and Other Processes

Rudshteyn

Castillo

Ghogare

et al. 2013

Photochem & Photobiology

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Photobiologic and synthetic versatility of hydrazones has not yet been established with 1O2 as a route to commonly encountered nitrosamines. Thus, to determine whether the “parent” reaction of formalhydrazone and 1O2 leads to facile C=N bond cleavage and resulting nitrosamine formation, we have carried out CCSD(T)//DFT calculations and analyzed the energetics of the oxidation pathways. A [2 + 2] pathway occurs via diradicals and formation of 3-amino-1,2,3-dioxazetidine in a 16 kcal/mol process. Reversible addition or physical quenching of 1O2 occurs either on the formalhydrazone carbon for triplet diradicals at 2–3 kcal/mol, or on the nitrogen (N(3)) atom forming zwitterions at ~15 kcal/mol, although the quenching channel by charge-transfer interaction was not computed. The computations also predict a facile conversion of formalhydrazone and 1O2 to hydroperoxymethyl diazene in a low-barrier ‘ene’ process, but no 2-amino-oxaziridine-O-oxide (perepoxide-like) intermediate was found. A Benson-like analysis (group increment calculations) on the closed shell species are in accord with the quantum chemical results.

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“…Effect of solvent on singlet-oxygen quenching constants. Previous studies have shown that the singlet-oxygen quenching constants for various amines, hydrazines and iodide ion are smaller in solvents with high values on the ␣ scale (11,(20)(21)(22). This is because amines, hydrazines and iodide ion are easily protonated.…”

Section: Discussionmentioning

confidence: 97%

“…The effect of solvent on the quenching of singlet oxygen by other types of molecules, such as amines, has been analyzed using the solvatochromic parameters of Kamlet, Abboud, Abraham and Taft (18)(19)(20)(21)(22). Typically, three scales are used to gain insight into the mechanism of quenching.…”

Section: Rtmentioning

confidence: 99%

Structural and Environmental Requirements for Quenching of Singlet Oxygen by Cyanine Dyes †

Kanofsky

Sima

2007

Photochemistry and Photobiology

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Singlet‐oxygen quenching constants were measured for 19 cyanine dyes in acetonitrile. The most efficient quenchers were 1‐butyl‐2‐[2‐[3‐[(1‐butyl‐6‐chlorobenz[cd]indol‐2(1H)‐ylidene)ethylidene]‐2‐chloro‐1‐cyclohexen‐1‐yl]ethenyl]‐6‐chlorobenz[cd]indolium and 6‐chloro‐2‐[2‐[3‐(6‐chloro‐1‐ethylbenz[cd]indol‐2(1H)‐ylidene)ethylidene]‐2‐phenyl‐1‐cyclopenten‐1‐yl]ethenyl]‐1‐ethylbenz[cd]indolium, having quenching constants with diffusion‐controlled values of 2.0 ± 0.1 × 1010 and 1.5 ± 0.1 × 1010M−1 s−1, respectively. There was a trend toward increased quenching constants for cyanine dyes with the absorption band maxima at longer wavelengths. However, the quenching constants correlated better with the oxidation potentials of the cyanine dyes, suggesting that quenching proceeds by charge transfer rather than energy transfer. The quenching constants for 1,1′,3,3,3′,3′‐hexamethylindotricarbocyanine perchlorate and 1,1′‐diethyl‐4,4′‐carbocyanine iodide were measured in several solvents as well as in aqueous solutions of detergent micelles. In different solvents, the quenching constants varied by as much as a factor of 50. The quenching constants were largest in solvents with the highest values on the π* scale of Kamlet, Abboud, Abraham and Taft. This was consistent with quenching occurring by charge transfer. Within cells, cyanine dyes concentrate in membrane‐bound organelles. The quenching constants were substantial within detergent micelles. To the extent that micelles are models for biological membranes, cyanine dyes may be effective biological singlet‐oxygen quenchers.

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Hydrazines: new charge-transfer physical quenchers of singlet oxygen

Cited by 64 publications

References 0 publications

Identification of Ros Produced by Photodynamic Activity of Chlorophyll/Cyclodextrin Inclusion Complexes

Identification of Ros Produced by Photodynamic Activity of Chlorophyll/Cyclodextrin Inclusion Complexes

Theoretical Study of the Reaction Formalhydrazone with Singlet Oxygen. Fragmentation of the C=N Bond, Ene Reaction and Other Processes

Structural and Environmental Requirements for Quenching of Singlet Oxygen by Cyanine Dyes †

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