Time-Resolved Photoacoustics Determination of Intersystem Crossing and Singlet Oxygen Photosensitization Quantum Yields for 4,5',8-Trimethylpsoralen

1995 ◽  
Vol 99 (43) ◽  
pp. 16162-16167 ◽  
Author(s):  
Aba Losi ◽  
Roberta Bedotti ◽  
Cristiano Viappiani
Keyword(s):  
Singlet Oxygen ◽  
Quantum Yields ◽  
Intersystem Crossing ◽  
Time Resolved

scholarly journals Exploiting radical-pair intersystem crossing for maximizing singlet oxygen quantum yields in pure organic fluorescent photosensitizers

2020 ◽  
Vol 11 (40) ◽  
pp. 10921-10927
Author(s):  
Xuanhang Wang ◽  
Yucong Song ◽  
Guocui Pan ◽  
Wenkun Han ◽  
Boyu Wang ◽  
...  
Keyword(s):  
Singlet Oxygen ◽  
Radical Pair ◽  
Quantum Yields ◽  
Intersystem Crossing ◽  
Molecular Symmetry

Maximizing singlet oxygen quantum yields of a fluorescent photosensitizer for realizing approximately 100% utilization of excitons by precisely controlling the molecular symmetry.

Deep-cavity subporphyrazines with extended π-perimeters

2016 ◽  
Vol 20 (08n11) ◽  
pp. 1277-1283 ◽  
Author(s):  
Roman Münnich ◽  
Patricia Löser ◽  
Andreas Winzenburg ◽  
Rüdiger Faust
Keyword(s):  
Cyclic Voltammetry ◽  
Singlet Oxygen ◽  
The Other ◽  
Quantum Yields ◽  
Spectroscopic Techniques ◽  
Fluorine Substitution ◽  
Deep Cavity ◽  
Other Hand ◽  
Specific Induction

Unprecedentedly large subporphyrazines (SubPz) with dibenzoquinoxalino-fusion and peripheral phenyl substitution were prepared by the cyclization of perfluorated or non-fluorous polyphenyl-substituted quinoxaline dinitriles and characterized by spectroscopic techniques. The compounds suitability to act as photosensitizers was explored by wavelength-specific induction of singlet oxygen luminescence and was shown to be excellent. Determination of 1O2-quantum yields suggests that fluorine substitution enhances the photosensitization efficiencies of the SubPz. On the other hand, cyclic voltammetry reveals an increase of irreversible reductive processes in case of the fluorinated SubPz.

scholarly journals Fluorescent Liquid Tetrazines

Molecules ◽  
2021 ◽  
Vol 26 (19) ◽  
pp. 6047
Author(s):  
Maximilian Paradiz Paradiz Dominguez ◽  
Begüm Demirkurt ◽  
Marion Grzelka ◽  
Daniel Bonn ◽  
Laurent Galmiche ◽  
...  
Keyword(s):  
Photophysical Properties ◽  
Liquid Films ◽  
Quantum Yields ◽  
Intersystem Crossing ◽  
Time Resolved ◽  
Fluorescence Quantum Yields ◽  
Exciton Migration ◽  
Orange Fluorescence ◽  
The Difference ◽  
Chain Lengths

Tetrazines with branched alkoxy substituents are liquids at ambient temperature that despite the high chromophore density retain the bright orange fluorescence that is characteristic of this exceptional fluorophore. Here, we study the photophysical properties of a series of alkoxy-tetrazines in solution and as neat liquids. We also correlate the size of the alkoxy substituents with the viscosity of the liquids. We show using time-resolved spectroscopy that intersystem crossing is an important decay pathway competing with fluorescence, and that its rate is higher for 3,6-dialkoxy derivatives than for 3-chloro-6-alkoxytetrazines, explaining the higher fluorescence quantum yields for the latter. Quantum chemical calculations suggest that the difference in rate is due to the activation energy required to distort the tetrazine core such that the nπ*S1 and the higher-lying ππ*T2 states cross, at which point the spin-orbit coupling exceeding 10 cm−1 allows for efficient intersystem crossing to occur. Femtosecond time-resolved anisotropy studies in solution allow us to measure a positive relationship between the alkoxy chain lengths and their rotational correlation times, and studies in the neat liquids show a fast decay of the anisotropy consistent with fast exciton migration in the neat liquid films.

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