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Excitation-Dependent Quadruple-Level Emission from an Isolated Molecule for Dynamic Information Encryption
Yibo Shi1, Lin Liu1, Wei-Hai Fang1
1Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, 100875, China.
Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
|July 11, 2025
Summary
Researchers developed a novel organic molecule exhibiting excitation-dependent (Ex-De) multi-emission, switching between fluorescence and phosphorescence. This breakthrough enables advanced multi-dimensional information encryption using single-molecule responsive luminophores.
Area of Science:
- Materials Science
- Organic Chemistry
- Photophysics
Background:
- Stimuli-responsive single-molecule materials are crucial for smart luminescence applications.
- Controlling electron transfer and energy levels is key to achieving tunable emission properties.
- Existing materials often lack excitation-dependent (Ex-De) multi-emission capabilities.
Purpose of the Study:
- To demonstrate a new strategy for manipulating electron transfer via donor-acceptor decoupling.
- To achieve excitation-dependent (Ex-De) single-molecule emission with switchable fluorescence and phosphorescence.
- To develop materials for time-resolved and excitation-responsive multi-dimensional information encryption.
Main Methods:
- Synthesis of a novel organic molecule: 10-phenyl-10H,13'H-spiro[acridine 9,6'-pentacen]-13'-one (ACRSP).
- Investigation of emission properties in different environments (solution and PMMA).
- Experimental and computational analysis of exciton spin ratios and emissive state compositions.
- Characterization of donor-acceptor decoupling and triplet level inversion effects.
Main Results:
- ACRSP exhibits anti-Kasha quadruple-level emission and opposite Ex-De afterglow in different environments.
- Dual Ex-De behavior observed, with fluorescence in solution and phosphorescence-fluorescence in PMMA.
- Room-temperature phosphorescence (RTP) coexistence achieved with a lifetime of 770.54 ms.
- Exciton spin ratios and emissive state compositions are modulated by excitation modes.
Conclusions:
- Donor-acceptor decoupling and triplet level inversion are effective strategies for Ex-De behavior and RTP.
- The developed ACRSP molecule offers tunable multi-emission for advanced optical applications.
- This work provides design principles for purely organic Ex-De systems and next-generation responsive luminophores.
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