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Controllable and Exceptionally Efficient Spin-Orbit Charge-Transfer Intersystem Crossing in Twisted π-Conjugated
Hui Liang1, Shangru Li2, Zixiang Zhou1
1Hubei Key Laboratory of Low Dimensional Optoelectronic Materials and Devices, Hubei University of Arts and Science, Xiangyang, People's Republic of China.
Angewandte Chemie (International Ed. in English)
|July 11, 2026
Summary
Researchers developed a novel heavy-atom-free photosensitizer using spin-orbit charge-transfer intersystem crossing (SOCT-ISC) in a perylene bisimide (PBI) framework. This breakthrough offers efficient triplet formation and broad applications in photochemistry.
Area of Science:
- Organic Chemistry
- Photochemistry
- Materials Science
Background:
- Designing efficient photosensitizers is crucial for photochemical applications.
- Heavy-atom-free compounds are desirable for reduced toxicity and cost.
- Controlling intersystem crossing (ISC) efficiency in twisted π-conjugated systems remains a challenge.
Purpose of the Study:
- To rationally design a heavy-atom-free photosensitizer with enhanced spin-orbit charge-transfer intersystem crossing (SOCT-ISC) characteristics.
- To overcome limitations in ISC efficiency and energy dissipation in twisted π-conjugated systems.
- To explore the photophysical properties and applications of the designed photosensitizer.
Main Methods:
- Incorporation of SOCT-ISC characteristics into a twisted π-conjugated perylene bisimide (PBI) framework.
- Modulation of charge transfer (CT) state energy via solvent polarity.
- Characterization of photophysical properties including absorption, triplet excited state energy, and ISC efficiency.
- Application in energy-transfer-based upconversion, photocatalysis, and atom-transfer radical polymerization.
Main Results:
- A novel photosensitizer (FQAOPBI) was synthesized, exhibiting broad absorption (300-600 nm).
- Achieved unprecedented ISC efficiency (ΦΔ = 95%) and a long-lived triplet excited state (101 µs).
- Demonstrated high efficiency (13.1%) in energy-transfer-based upconversion and effective photocatalysis for photooxidation and polymerization.
Conclusions:
- The developed FQAOPBI photosensitizer overcomes design constraints for SOCT-ISC, enabling efficient triplet formation.
- This heavy-atom-free PBI derivative shows significant promise for diverse photochemical applications, including upconversion and photocatalysis.
- The findings are expected to guide future photosensitizer design and advance photochemical technologies.
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