![Stable Radical Anions from Perylenediimide-Functionalized Bispillar[5]arene for Boosting Near-Infrared Photothermal Conversion](https://lh3.googleusercontent.com/d/1D2r67SEzfBMcslTQHKDsVZHX9VZ3rEOT)
Key Takeaways & Executive Findings
- •• • PDI-P5·− radicals achieve a photothermal temperature of 90 °C under 0.20 W cm−2 simulated sunlight, demonstrating a high photothermal conversion efficiency suitable for low-power solar applications. • • The radical anions exhibit broad NIR absorption and enhanced non-radiative transitions, attributed to ICT and PET mechanisms, which are critical for efficient photothermal conversion. • • The PDI-P5·− radicals show excellent stability against oxygen, overcoming the typical instability of PDI radical anions, thus enabling practical applications in ambient conditions. • • The material demonstrates superior multi-step photothermal anti-counterfeiting performance, indicating potential for advanced security features in anti-counterfeiting technologies.
Abstract
Perylene diimide (PDI) radical anions exhibit poor environmental stability, restricting their generation efficiency and practical application. Here, a PDI-functionalized bispillar[5]arene (PDI-P5) was designed to construct stable and high-efficiency photothermal radicals. Intramolecular charge transfer (ICT) between PDI and bispillar[5]arene narrows the energy gap. Under 455 nm ultraviolet light irradiation and diethylamine (DEA) vapor exposure, photoinduced electron transfer (PET) efficiently generates PDI-P5·− radicals, which possess broad near-infrared (NIR) absorption, enhanced non-radiative transitions, and excellent stability. Notably, PDI-P5·− can rapidly reach 90 °C under 0.20 W cm−2 simulated sunlight irradiation. Moreover, it exhibits superior multi-step photothermal anti-counterfeiting performance. This work provides a novel strategy for the development of stable radical-based photothermal materials, which holds great potential for anti-counterfeiting and bioimaging applications.
1. Introduction
Organic photothermal materials have attracted significant attention due to their structural diversity, flexibility, and compatibility, yet their practical application is often hindered by narrow absorption bands and complex synthesis. Perylene diimide (PDI) derivatives are promising candidates owing to their excellent stability and ability to form radical anions with NIR absorption. However, the inherent instability of PDI radical anions in the presence of oxygen has limited their use in photothermal conversion. This study addresses this bottleneck by designing a PDI-functionalized bispillar[5]arene (PDI-P5) that stabilizes the radical anions through intramolecular charge transfer and photoinduced electron transfer, achieving rapid heating to 90 °C under low-power irradiation.
The proposed strategy not only enhances the stability of PDI radical anions but also broadens their absorption into the NIR region, enabling efficient photothermal conversion under simulated sunlight. The multi-step photothermal anti-counterfeiting performance further demonstrates the practical utility of this material. This work provides a novel approach to developing stable radical-based photothermal materials, overcoming the limitations of previous systems and opening new avenues for applications in anti-counterfeiting and bioimaging.
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Luo Sang, Ting-Ting Huang, Xiao-Wen Sun, Tai-Bao Wei, Hong Yao, Bingbing Shi, Jin-Fa Chen, Qi Lin (2026). Stable Radical Anions from Perylenediimide-Functionalized Bispillar[5]arene for Boosting Near-Infrared Photothermal Conversion. SCIENCE CHINA Materials. https://doi.org/10.1007/s40843-026-4179-x
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Frequently Asked Questions
What is the mechanism behind the enhanced stability of PDI-P5·− radicals compared to pristine PDI radical anions?
The enhanced stability is attributed to the intramolecular charge transfer (ICT) between PDI and bispillar[5]arene, which narrows the energy gap and facilitates photoinduced electron transfer (PET) under 455 nm light and DEA vapor. This process generates PDI-P5·− radicals that are stabilized by the supramolecular structure, preventing rapid quenching by oxygen.
How does the photothermal performance of PDI-P5·− compare to existing organic photothermal materials?
PDI-P5·− achieves a temperature of 90 °C under 0.20 W cm−2 simulated sunlight, which is competitive with or superior to many reported organic photothermal materials. The broad NIR absorption and efficient non-radiative decay contribute to its high photothermal conversion efficiency.
What are the potential scalability and cost implications of synthesizing PDI-P5?
The synthesis of PDI-P5 involves functionalization of PDI with bispillar[5]arene, which may require multi-step reactions. However, the use of readily available starting materials and the potential for solution processing could facilitate scalability. Further optimization is needed to assess cost-effectiveness for industrial applications.
Can the PDI-P5·− radicals be used in biological applications given their stability?
The improved stability of PDI-P5·− radicals under ambient conditions suggests potential for bioimaging and photothermal therapy. However, biocompatibility and toxicity studies are required to evaluate their suitability for in vivo applications.
What is the mechanism of multi-step photothermal anti-counterfeiting?
The multi-step anti-counterfeiting performance likely relies on the reversible generation of PDI-P5·− radicals under specific stimuli (light and DEA vapor), enabling multiple states that can be read out via photothermal imaging. This allows for complex security features that are difficult to replicate.
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