Volume 64, Issue 30 e202505353
Research Article

Stabilizing the Quinoidal Form of Polycyclic Aromatic Hydrocarbons by O─B←N Units to Give a > 1000 nm Redshift in the Absorption Wavelength

Canyun Mao

Canyun Mao

State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022 P.R. China

School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, 230026 P.R. China

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Dr. Xingxin Shao

Corresponding Author

Dr. Xingxin Shao

State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022 P.R. China

E-mail: [email protected]; [email protected]

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Prof. Jun Liu

Corresponding Author

Prof. Jun Liu

State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022 P.R. China

School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, 230026 P.R. China

E-mail: [email protected]; [email protected]

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Prof. Lixiang Wang

Prof. Lixiang Wang

State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022 P.R. China

School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, 230026 P.R. China

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First published: 19 May 2025

Graphical Abstract

By incorporating four O─B←N units into naphthalene diimide, the core is transformed from an aromatic form to a quinoidal form, significantly enhancing π-electron delocalization. This results in a reduced bandgap from 3.10 to 0.88 eV and a redshift in absorption from 400 to 1410 nm. The synthesized polycyclic aromatic hydrocarbon exhibits strong SWIR absorption and high transparency in the visible region, developing a colorless anti-counterfeiting application.

Abstract

Polycyclic aromatic hydrocarbons (PAHs) have distinct chemical structures and excellent optoelectronic properties. Although PAHs with ultra-large π-conjugated skeletons have been successfully synthesized, ultrasmall bandgap (Eg < 1.2 eV) or short-wavelength infrared (SWIR) light absorption (λ > 1000 nm) is seldom reported for PAHs. In this work, we design and synthesize a PAH by incorporating four O─B←N units into naphthalene diimide (NDI) as the core. The incorporation of four O─B←N units changes the NDI core from an aromatic form to a quinoidal form, leading to significantly enhanced π-electron delocalization. As a result, the optical bandgap of the molecule decreases from 3.10 to 0.88 eV, and the onset absorption wavelength is redshifted from 400 to 1410 nm. The resulting molecule exhibits strong light absorption in the infrared region and high transparency in the visible region. It can be used to develop colorless infrared anti-counterfeiting technology. This work provides a novel molecular design strategy to tune optoelectronic properties of PAHs.

Conflict of Interests

The authors declare no conflict of interest.

Data Availability Statement

The data that support the findings of this study are available in the supporting information of this article.

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