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Facile Preparation of 2Z,4E-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
Published on: June 21, 2017
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Electronic properties of 4-substituted naphthalimides
Pavel Kucheryavy1, Guifeng Li, Shubham Vyas
1Department of Chemistry, Bowling Green State University, Bowling Green, Ohio 43403, USA.
The Journal of Physical Chemistry. A
|May 19, 2009
Summary
This study investigates excited-state properties of naphthalimide derivatives. The findings reveal distinct electronic transitions and decay pathways, crucial for understanding their photophysical behavior.
Area of Science:
- Photochemistry
- Organic Chemistry
- Spectroscopy
Background:
- Naphthalimide derivatives are important fluorophores.
- Understanding their excited-state properties is key to designing new materials.
Purpose of the Study:
- To investigate the excited-state properties and dynamics of naphthalimide and its derivatives.
- To correlate structural modifications with photophysical behavior.
Main Methods:
- Steady-state absorption and fluorescence spectroscopy.
- Femtosecond transient absorption spectroscopy.
- Time-dependent density functional theory (TD-DFT) calculations.
Main Results:
- All derivatives populate the S(2) state (n,pi* character) upon excitation.
- Internal conversion from S(2) to S(1) occurs within 40 ps.
- The S(1) state exhibits charge-transfer character for electron-donating/withdrawing substituted derivatives, and pi,pi* character for unsubstituted and chloro-substituted naphthalimides.
- S(1) state lifetimes are ~4 ns, with intersystem crossing to the T(1) state observed within 400 ps for NI and Cl-NI.
Conclusions:
- The excited-state character and decay pathways of naphthalimide derivatives are strongly influenced by substituents.
- Substituent effects dictate the balance between internal conversion and intersystem crossing.
- These findings provide insights into the photophysics of naphthalimides for potential applications.
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