Solvent-dependent singlet oxygen lifetimes: temperature effects implicate tunneling and charge-transfer interactions

2016 ◽  
Vol 18 (33) ◽  
pp. 22946-22961 ◽  
Author(s):  
Mikkel Bregnhøj ◽  
Michael Westberg ◽  
Frank Jensen ◽  
Peter R. Ogilby
Keyword(s):  
Charge Transfer ◽  
Singlet Oxygen ◽  
Temperature Effects ◽  
New Model

A new model for an old problem: a barrier to account for temperature effects on singlet oxygen lifetimes.

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

On the Thermal Effects in a Warp Beam (A Wound-Yarn-Package)

1978 ◽  
Vol 100 (1) ◽  
pp. 8-12
Author(s):  
S. K. Batra ◽  
D. S. Lee ◽  
S. Backer
Keyword(s):  
Stress Field ◽  
Thermal Effects ◽  
Temperature Effects ◽  
Continuum Model ◽  
Prolonged Storage ◽  
New Model ◽  
Cylindrically Anisotropic

The development of the stress field in a cylindrically-wound-yarn-package with side flanges (warp beams), during winding, can be predicted [6] using Beddoe’s [4] cylindrically anisotropic continuum model. This model is extended to account for the temperature effects observed during prolonged storage of the beams. The results predicted by the new model compare well with the experimental observations.

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.

Reversible exciplex formation between singlet oxygen, 1.DELTA.g, and vitamin E. Solvent and temperature effects

1984 ◽  
Vol 106 (23) ◽  
pp. 6956-6959 ◽  
Author(s):  
Anthony A. Gorman ◽  
I. R. Gould ◽  
I. Hamblett ◽  
M. C. Standen
Keyword(s):  
Vitamin E ◽  
Singlet Oxygen ◽  
Temperature Effects ◽  
Exciplex Formation

Singlet Oxygen Production in Water:  Aggregation and Charge-Transfer Effects

1996 ◽  
Vol 100 (16) ◽  
pp. 6555-6560 ◽  
Author(s):  
Charles Tanielian ◽  
Christian Wolff ◽  
Marc Esch
Keyword(s):  
Charge Transfer ◽  
Singlet Oxygen ◽  
Oxygen Production ◽  
Transfer Effects

Influence of protonation of peripheral substituents on photophysical and photochemical properties of tetrapyrazinoporphyrazines

2010 ◽  
Vol 14 (07) ◽  
pp. 582-591 ◽  
Author(s):  
Veronika Novakova ◽  
Eva H. Mørkved ◽  
Miroslav Miletin ◽  
Petr Zimcik
Keyword(s):  
Charge Transfer ◽  
Sulfuric Acid ◽  
Singlet Oxygen ◽  
Electron Pair ◽  
Intramolecular Charge Transfer ◽  
Quantum Yields ◽  
Considerable Decrease ◽  
Fluorescence Quantum Yields ◽  
Photochemical Properties ◽  
Free Electron Pair

Octasubstituted zinc tetrapyrazinoporphyrazines with four N,N-dimethylaminophenyls and four phenyl or pyridin-3-yl substituents were synthesized and fully characterized. Their fluorescence quantum yields in DMF or pyridine were very low, almost undetectable, as a consequence of ultrafast intramolecular charge transfer. Titration of their DMF solutions with sulfuric acid led to increase of the fluorescence quantum yields by two orders of magnitude when the full protonation of peripheral substituents was achieved. Intramolecular charge transfer is no longer a favorable way of excited-state relaxation at full protonation of N,N-dimethylaminophenyl substituents because of loss of donor centers (free electron pair on its nitrogen). Similarly, singlet oxygen quantum yields also increased by two orders of magnitude when sulfuric acid was added to tetrapyrazinoporphyrazine solutions in DMF. Protonation at azomethine nitrogens of tetrapyrazinoporphyrazine macrocycle was observed at higher acid concentrations and it led to considerable decrease of fluorescence quantum yields. Octaphenyl zinc tetrapyrazinoporphyrazine and octa(pyridin-3-yl) zinc tetrapyrazinoporphyrazine were used as controls without intramolecular charge transfer. Their fluorescence and singlet oxygen quantum yields were high in DMF and decreased at higher concentrations of sulfuric acid due to protonation of azomethine nitrogens. The results suggest that the photophysical and photochemical properties of studied compounds may be controlled by changes of pH of medium.

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