Distance Dependence for Intramolecular Electron Transfer from Excited Naphthalenediimide Dianion
Chao Lu1, Hiroki Nakayama1, Yasuko Osakada1
1SANKEN (The Institute of Scientific and Industrial Research), The University of Osaka, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan.
The Journal of Physical Chemistry. A
|December 22, 2025
Summary
This study reveals the excited-state properties and electron transfer dynamics of naphthalenediimide dianion (NDI2-*). Intramolecular electron transfer was observed, with backward electron transfer showing significant distance dependence.
Area of Science:
- Photochemistry and photophysics of organic molecules.
- Advanced materials science and organic electronics.
- Spectroscopic investigation of excited states.
Background:
- Naphthalenediimide dianions (NDI2-) are key components in organic electronics.
- Understanding excited-state properties and electron transfer (ET) is crucial for material design.
- Previous studies lacked detailed insights into NDI2- excited-state dynamics.
Purpose of the Study:
- To comprehensively explore the properties of excited naphthalenediimide dianion (NDI2-*).
- To investigate the intramolecular electron transfer (ET) dynamics in NDI2--acceptor dyads.
- To elucidate the distance dependence of ET and backward electron transfer (BET) in these systems.
Main Methods:
- Utilized subnanosecond and subpicosecond transient absorption spectroscopies.
- Studied NDI2- and NDI2--acceptor (A) dyads with varied spacer lengths.
- Analyzed fluorescence lifetime and quantum yield of NDI2-.
Main Results:
- NDI2-* exhibits singlet (S1) and triplet (T1) states with lifetimes of 13 ns and >200 ns.
- Fluorescence lifetime of 13.3 ns and quantum yield of 0.71 were measured for NDI2-.
- Efficient intramolecular ET occurred within picoseconds; BET showed distance dependence and extended lifetime due to increased energy barrier.
Conclusions:
- Provided the first clear description of excited-state and photoinduced ET features of NDI2-.
- Demonstrated distance-dependent ET and BET, crucial for designing NDI2- based materials.
- Laid the foundation for future photochemical studies of excited multi-ions in advanced semiconducting materials.
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