Singlet and triplet quenching of indole by heavy atom containing molecules in a low temperature glassy matrix. Evidence for complexation in the triplet state

Lessard, Ginette; Durocher, Gilles

doi:10.1021/j100515a013

Cited by 23 publications

(9 citation statements)

References 11 publications

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“…Sodium azide (NaN 3 ), a physical scavenger of 1 O 2 , 32 barely inhibited the NADH photooxidation. Furthermore, potassium iodide (KI), a triplet quencher, 33 did not show an inhibitory effect on this photooxidation (Supporting Information). These results suggest that neither the triplet excited (T 1 ) state of these phenothiazine dyes nor 1 O 2 are responsible for NADH oxidation.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Phenothiazine Dyes Induce NADH Photooxidation through Electron Transfer: Kinetics and the Effect of Copper Ions

Hirakawa

Mori

2021

ACS Omega

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Phenothiazine dyes, methylene blue, new methylene blue, azure A, and azure B, photosensitized the oxidation of nicotinamide adenine dinucleotide (NADH), an important coenzyme in the living cells, through electron transfer. The reduced forms of these phenothiazine dyes, which were produced through electron extraction from NADH, underwent reoxidation to the original cationic forms, leading to the construction of a photoredox cycle. This reoxidation process was the rate-determining step in the photoredox cycle. The electron extraction from NADH using phenothiazine dyes can trigger the chain reaction of the NADH oxidation. Copper ions enhanced the photoredox cycle through reoxidation of the reduced forms of phenothiazine dyes. New methylene blue demonstrated the highest photooxidative activity in this experiment due to the fast reoxidation process. Electron-transfer-mediated oxidation and the role of endogenous metal ions may be important elements in the photosterilization mechanism.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Phenothiazine Dyes Induce NADH Photooxidation through Electron Transfer: Kinetics and the Effect of Copper Ions

Hirakawa

Mori

2021

ACS Omega

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“…The heavy atoms increase the intersystem crossing process (ISC) to form a triplet exciplex or encounter complex that dissociates according to the scheme In this process the short-lived intermediate states are not detectable. This scheme is generally accepted − , and indicates that external heavy atom fluorescence quenching occurs when the heavy atom is in the environment of the fluorescing molecule causing spin−orbit coupling. This quenching is short-range, requiring close contact between the fluorophore and heavy atom quencher.…”

Section: Resultsmentioning

confidence: 99%

“…Collisional quenching of fluorescence has been widely used in physical chemistry and biochemistry. Fluorescence quenching of aromatic and heteroaromatic hydrocarbons by aromatic amines, − aromatic nitriles, haloalkanes, − and halide ions − as well as by nitroxides , and oxygen , has been studied to determine the bimolecular rate constants, to characterize the solvent effects on quenching, and to determine the mechanisms of interaction between the fluorophore and quencher molecules. Moreover, collisional quenching of tryptophan fluorescence by a variety of ionic and neutral quenchers has been used to study the structure and dynamics of proteins − and membranes. , Collisional or dynamic quenching requires contact between the fluorophore and quencher molecules during the lifetime of the excited state.…”

Section: Introductionmentioning

confidence: 99%

Distance-Dependent Fluorescence Quenching ofp-Bis[2-(5-phenyloxazolyl)]benzene by Various Quenchers

et al. 1996

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We report results of frequency-domain and steady-state measurements of the fluorescence quenching of p-bis-[2-(5-phenyloxazolyl)]benzene (POPOP) when quenched by bromoform (CHBr 3 ), methyl iodide (CH 3 I), potassium iodide (KI), 1,2,4-trimethoxybenzene (TMB), or N,N-diethylaniline (DEA). The quenching efficiency of these compounds decreased in the order DEA, TMB, KI, CH 3 I, CHBr 3 . In the case of DEA and TMB the measurements clearly confirm the applicability of the exponential distance-dependent quenching (DDQ) model, in which the bimolecular quenching rate k(r) depends exponentially on the fluorophore-quencher separation r, k(r) ) k a exp[-(r -a)/r e ], where a is the distance of closest approach. Simultaneous analysis of the frequency-domain and steady-state data significantly improved resolution of the recovered molecular parameters k a and r e . The data for DEA and TMB cannot be satisfactorily fit using either the Smoluchowski or CollinsKimball radiation boundary condition (RBC) model. The quenching behavior of the less efficient quenchers KI, CH 3 I, and CHBr 3 can be adequately described with both the DDQ and RBC models, but this may be a simple consequence of less efficient quenching. The efficiency of quenching is discussed on the basis of the mechanisms of interaction between the fluorophore and quencher molecules, which involves electron transfer and/or heavy atom effects. IntroductionCollisional quenching of fluorescence has been widely used in physical chemistry and biochemistry. Fluorescence quenching of aromatic and heteroaromatic hydrocarbons by aromatic amines, 1-13 aromatic nitriles, 14 haloalkanes, 15-24 and halide ions 25-27 as well as by nitroxides 28,29 and oxygen 30,31 has been studied to determine the bimolecular rate constants, to characterize the solvent effects on quenching, and to determine the mechanisms of interaction between the fluorophore and quencher molecules. Moreover, collisional quenching of tryptophan fluorescence by a variety of ionic and neutral quenchers has been used to study the structure and dynamics of proteins 32-40 and membranes. 41,42 Collisional or dynamic quenching requires contact between the fluorophore and quencher molecules during the lifetime of the excited state. The quenching data can reveal information about accessibility of fluorophores in macromolecules to externally added quenchers and the diffusion of quenchers within proteins and membranes.For many fluorophores in solution, including aromatic and heteroaromatic fluorophores, the intensity decays are often monoexponential. 43 However, in the presence of collisional quenching the monoexponential intensity decays become nonexponential due to transient effects in diffusion. 21,[44][45][46] This effect in collisional quenching of fluorescence is due to a rapid decay of closely spaced fluorophore-quencher pairs, followed by slower diffusion-limited quenching of remaining fluorophores. These effects can be readily detected by using frequency-domain fluorometry. [47][48][49] We have shown for several fl...

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“…Iodide, bromide and alkyl halides are well established as heavy-atom perturbers of luminescence of aromatic and heteroaromatic fluorophores [28,[49][50][51][52][53][54] including indole [49,50] and tryptophan [49]. The presence of heavy atoms or heavy atom containing molecules in the environment increases the rates of spin-forbidden processes of the fluorophores via a spin-orbital coupling mechanism.…”

Section: Mechanisms Of Tryptophan Fluorescence Quenchingmentioning

confidence: 99%

Time-resolved and steady-state fluorescence quenching of N-acetyl-l-tryptophanamide by acrylamide and iodide

Zelent

Kuśba

Gryczyński

et al. 1998

Biophysical Chemistry

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We examined the time-resolved and steady-state fluorescence quenching of N-acetyl-L-tryptophanamide (NATA) by acrylamide and iodide, over a range of viscosities in propylene glycol. The quenching of NATA by acrylamide and iodide results in heterogeneity of the intensity decay which increases with the quencher concentration. We attribute the complex decays of NATA to transient effects in diffusion and the nature of the fluorophore-quencher interaction. These data were compared using the phenomenological radiation boundary condition (RBC) and distance-dependent quenching (DDQ) models for collisional quenching. We used global analysis of the time-resolved frequency-domain and steady-state data to select between the models. Consideration of both the frequency-domain and steady state data demonstrate that the quenching rate depends exponentially on the fluorophore-quencher distance, indicating the validity of the DDQ model. The rate constants for acrylamide and iodide quenching, at the constant distance of 5 A, were found to be near 10(13) s-1 and 10(9) s-1, respectively. These rates reflect electron transfer and exchange interactions as the probable quenching mechanisms, respectively.

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Singlet and triplet quenching of indole by heavy atom containing molecules in a low temperature glassy matrix. Evidence for complexation in the triplet state

Cited by 23 publications

References 11 publications

Phenothiazine Dyes Induce NADH Photooxidation through Electron Transfer: Kinetics and the Effect of Copper Ions

Phenothiazine Dyes Induce NADH Photooxidation through Electron Transfer: Kinetics and the Effect of Copper Ions

Distance-Dependent Fluorescence Quenching ofp-Bis[2-(5-phenyloxazolyl)]benzene by Various Quenchers

Time-resolved and steady-state fluorescence quenching of N-acetyl-l-tryptophanamide by acrylamide and iodide

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