The balance between charge transfer and non-charge transfer pathways in the sensitization of singlet oxygen by ππ* triplet states

2005 ◽  
Vol 4 (6) ◽  
pp. 481 ◽  
Author(s):  
Reinhard Schmidt
Keyword(s):  
Charge Transfer ◽  
Singlet Oxygen ◽  
Triplet States

On the Mechanism of Quenching by Amines: A New Method for Investigation of Interactions with Triplet States

1974 ◽  
Vol 52 (16) ◽  
pp. 2889-2893 ◽  
Author(s):  
Robert H. Young ◽  
D. Brewer ◽  
R. Kayser ◽  
R. Martin ◽  
D. Feriozi ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Charge Transfer ◽  
Singlet Oxygen ◽  
Rose Bengal ◽  
Rate Constants ◽  
Direct Method ◽  
Diffusion Limit ◽  
Triplet States ◽  
Novel Approach ◽  
Series Of Experiments

Rate constants for the quenching of singlet oxygen by a series of substituted N,N-dimethylanilines were obtained by a direct method employing a dye-laser. The Hammett ρ value obtained from the data (−1.71) suggests that a (partial) charge-transfer complex may be responsible for the quenching action. This rate data was combined with that obtained for the total quenching action on the sensitized photooxidation of 1,3-diphenylfuran. The quenching action on the photooxidation reaction is due to both the quenching of singlet oxygen and the quenching of the triplet state of the sensitizer (rose bengal or methylene blue). The combination of the data from each series of experiments resulted in rate constants of quenching of the triplet states of the sensitizers. A number of the N,N-dimethylanilines quenched the triplet states at the diffusion limit. Hammett ρ values (−1.86 for rose bengal and −4.19 for methylene blue) indicate that charge-transfer intermediates are probably responsible for the quenching action. This was confirmed by the observation of a transient intermediate assigned to the charge-transfer radical of methylene blue. The technique used here represents a novel approach to the investigation of triplet states.

Lifetime of Singlet Oxygen and Quenching by NaN3 in Mixed Solvents

1982 ◽  
Vol 37 (5) ◽  
pp. 649-652 ◽  
Author(s):  
N. Miyoshi ◽  
M. Ueda ◽  
K. Fuke ◽  
Y. Tanimoto ◽  
M. Itoh ◽  
...  
Keyword(s):  
Activation Energy ◽  
Charge Transfer ◽  
Singlet Oxygen ◽  
Mixed Solvents ◽  
Solvent Polarity ◽  
Thermal Lensing ◽  
Partial Charge ◽  
Partial Charge Transfer ◽  
Quenching Rate ◽  
Quenching Rate Constant

Singlet oxygen was generated by the photosensitization of erythrosine. The lifetime of singlet oxygen and the quenching rate constant for singlet oxygen by NaN3 were measured by a thermal lensing method in MeOH-H2O mixed solvents. The reciprocal of the lifetime increased linearly with the increase of the H2O mole fraction. Semi-log plot of the quenching constant against the reciprocal of the solvent polarity exhibited a linear relation. The quenching of the singlet oxygen by NaN3 may proceed through a partial charge-transfer intermediate. The activation energy for the quenching reaction of N3- + 1O2 →[N3·1O2-] increased with the increase of the solvent polarity. The lifetime was also measured in MeOH-ethyleneglycol mixed solvents, and its relation with viscosity was obtained

scholarly journals Charge-transfer heptamethine dyes for NIR singlet oxygen generation

2019 ◽  
Vol 55 (38) ◽  
pp. 5511-5514 ◽  
Author(s):  
John B. Jarman ◽  
Dennis A. Dougherty
Keyword(s):  
Charge Transfer ◽  
Triplet State ◽  
Singlet Oxygen ◽  
State Formation ◽  
Charge Transfer State ◽  
Previous Evidence ◽  
Oxygen Generation ◽  
Singlet Oxygen Generation ◽  
A Charge ◽  
Transfer State

A heptamethine-based charge-transfer dye was designed based on previous evidence of triplet state formation in orthogonal charge-transfer partners and calculations suggesting the formation of a charge-transfer state in heptamethine dye derivatives.

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