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Heavy atom effects on synthetic pyranoanthocyanin analogues
Lucas M O S Martins1, Gustavo T M Silva1, Lucas F S Hess1
1Instituto de Química, Universidade de São Paulo, São Paulo, SP, Brazil.
Photochemistry and Photobiology
|December 26, 2024
Summary
Synthetic pyranoflavylium cations with heavy atoms show minimal impact on their excited singlet state. However, heavy atoms slightly enhance phosphorescence and singlet oxygen formation, offering insights into wine color stability.
Area of Science:
- Photochemistry
- Organic Chemistry
- Wine Chemistry
Background:
- Pyranoanthocyanins, stable wine color compounds, are formed from grape anthocyanins.
- Pyranoflavylium cations serve as synthetic analogs for studying pyranoanthocyanins.
- Heavy atom substitution is explored to modulate photophysical properties.
Purpose of the Study:
- To investigate the photophysical properties of pyranoflavylium cations with bromo and iodo heavy atom substituents.
- To compare the effects of heavy atoms on excited state properties, including fluorescence, phosphorescence, and singlet oxygen formation.
- To understand the influence of heavy atom substitution on the S1 state and triplet formation.
Main Methods:
- Synthesis of nine pyranoflavylium cations with heavy atom substituents.
- Measurement of room temperature and 77 K fluorescence and phosphorescence.
- Determination of triplet formation in solution and singlet oxygen quantum yields.
- Suppression of excited state acidity using trifluoroacetic acid.
Main Results:
- Heavy atom effects on the S1 state photophysics of pyranoflavylium cations are minimal.
- Orbital nodal properties limit spin-orbit coupling into the excited singlet state.
- Heavy atom substitution shows a moderate increase in phosphorescence at 77 K.
- Triplet-sensitized singlet oxygen formation quantum yields are enhanced by heavy atoms.
Conclusions:
- Heavy atom substitution has a limited impact on the excited singlet state of pyranoflavylium cations due to specific orbital characteristics.
- Increased phosphorescence and singlet oxygen formation are observed with heavy atom substitution.
- These findings contribute to understanding the photophysics of wine color compounds and their synthetic analogs.
Keywords:
fluorescenceheavy atom effectphosphorescencepyranoanthocyaninspyranoflavylium cationssinglet oxygenMore Related Videos
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