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Ultrafast Time-resolved Near-IR Stimulated Raman Measurements of Functional π-conjugate Systems
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Ultrafast Electron Dynamics of a Ferrocene-Based Butadiyne-Bridged Complex
Kasun C Mendis1, Jesús Valdiviezo2,3, Susannah D Cox4
1Department of Chemistry, Tulane University, New Orleans, Louisiana 70118, United States.
The Journal of Physical Chemistry. A
|March 16, 2026
Summary
Photoinduced electron transfer in ferrocene-naphthalimide compounds is controlled by molecular flexibility. This study reveals how torsional dynamics and electronic coupling influence excited-state relaxation pathways for potential applications in solar energy.
Area of Science:
- Photochemistry and Photophysics
- Molecular Electronics
- Materials Science
Background:
- Photoinduced electron transfer (ET) in donor-bridge-acceptor (DBA) systems is tunable via bridge flexibility.
- Ferrocene (Fc)-based DBA compounds offer unique electronic properties due to Fe d-orbitals.
- Understanding excited-state dynamics is crucial for designing efficient photoactive materials.
Purpose of the Study:
- Investigate the excited-state dynamics of a ferrocene-butadiyne-naphthalimide (Fc-C4-NAP) compound.
- Elucidate the role of torsional flexibility and electronic coupling in ET pathways.
- Correlate computational predictions with experimental observations of ultrafast dynamics.
Main Methods:
- Femtosecond transient absorption (TA) spectroscopy in visible and mid-IR regions.
- Time-Dependent Density Functional Theory (TD-DFT) calculations.
- Analysis of excited-state manifolds and diabatic state coupling.
Main Results:
- Observed three distinct relaxation times (0.3-0.5 ps, ~2.6 ps, 17-20 ps) after 402 nm excitation.
- TD-DFT revealed strong coupling between acceptor-localized and ferrocene-based states, dependent on torsional angle.
- Fast relaxation attributed to a bright naphthalimide-centered state, followed by relaxation to ferrocene states.
Conclusions:
- Torsional dynamics and bridge-mediated coupling significantly influence excited-state evolution in Fc-C4-NAP.
- Efficient competition between energy transfer and charge separation pathways observed.
- Results provide insights for designing advanced photoactive materials for solar energy and molecular electronics.
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