3,4-Ethylenedithio thiophene donor for NIR-II fluorophores with improved quantum yields

Liu, Chunchen; Wang, Xinyuan; Zhu, Xingfu; Ma, Rui; Lin, Qihui; Liang, Yongye

doi:10.1039/d2qm01278b

“…This is caused by the unique depolarization resulting from the introduction of sulfur atoms. Compared to carbon and oxygen atoms, the sulfur atom has a larger atomic radius, indicating its greater capability for delocalizing electrons [20] . Moreover, the sulfur atom has lower electronegativity than oxygen, resulting in the lower polarizability of 3EHTT compared to EDOT and 3EHT.…”

Section: Resultsmentioning

confidence: 99%

Unlocking the NIR‐II AIEgen for High Brightness through Intramolecular Electrostatic Locking

Wang,

Yang,

Jiang

et al. 2024

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Fluorescent imaging and biosensing in the near‐infrared‐II (NIR‐II) window holds great promise for non‐invasive, radiation‐free, and rapid‐response clinical diagnosis. However, it’s still challenging to develop bright NIR‐II fluorophores. In this study, we report a new strategy to enhance the brightness of NIR‐II aggregation‐induced emission (AIE) fluorophores through intramolecular electrostatic locking. By introducing sulfur atoms into the side chains of the thiophene bridge in TSEH molecule, the molecular motion of the conjugated backbone can be locked through intramolecular interactions between the sulfur and nitrogen atoms. This leads to enhanced NIR‐II fluorescent emission of TSEH in both solution and aggregation states. Notably, the encapsulated nanoparticles (NPs) of TSEH show enhanced brightness, which is 2.6‐fold higher than TEH NPs with alkyl side chains. The in vivo experiments reveal the feasibility of TSEH NPs in vascular and tumor imaging with a high signal‐to‐background ratio and precise resection for tiny tumors. In addition, polystyrene nanospheres encapsulated with TSEH are utilized for antigen detection in lateral flow assays, showing a signal‐to‐noise ratio 1.9‐fold higher than the TEH counterpart in detecting low‐concentration antigens. This work highlights the potential for developing bright NIR‐II fluorophores through intramolecular electrostatic locking and their potential applications in clinical diagnosis and biomedical research.

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“…The introduction of chalcogenide-heavy atoms could reduce the band gap, taking advantage of the heavy atom effect to achieve a redshift in the absorption and emission. 102 Although this strategy could be employed to redshift the emission of conjugated materials to the NIR-II window, the QY decreases due to increasing intersystem crossing (ISC) decay. 103 For example, our group successfully developed the selenium (Se) substitution material IDSe-IC and the sulfur (S) substitution product IDS-IC, which resulted in a QY of 4.3% for IDSe-IC and a QY of 1.7% for IDS-IC in aqueous solution, respectively (Figure 3).…”

Section: Atomicmentioning

confidence: 99%

“…Atomic programming is another common strategy for developing NIR-II emissive conjugated materials. The introduction of chalcogenide-heavy atoms could reduce the band gap, taking advantage of the heavy atom effect to achieve a redshift in the absorption and emission . Although this strategy could be employed to redshift the emission of conjugated materials to the NIR-II window, the QY decreases due to increasing intersystem crossing (ISC) decay .…”

Section: Brightness Strategies Of Conjugated Materialsmentioning

confidence: 99%

Brightness Strategies toward NIR-II Emissive Conjugated Materials: Molecular Design, Application, and Future Prospects

Li,

Chen,

Su

et al. 2024

ACS Appl. Bio Mater.

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Recent advances have been made in second nearinfrared (NIR-II) fluorescence bioimaging and many related applications because of its advantages of deep penetration, high resolution, minimal invasiveness, and good dynamic visualization. To achieve high-performance NIR-II fluorescence bioimaging, various materials and probes with bright NIR-II emission have been extensively explored in the past few years. Among these NIR-II emissive materials, conjugated polymers and conjugated small molecules have attracted wide interest due to their native biosafety and tunable optical performance. This review summarizes the brightness strategies available for NIR-II emissive conjugated materials and highlights the recent developments in NIR-II fluorescence bioimaging. A concise, detailed overview of the molecular design and regulatory approaches is provided in terms of their high brightness, long wavelengths, and superior imaging performance. Then, various typical cases in which bright conjugated materials are used as NIR-II probes are introduced by providing step-by-step examples. Finally, the current problems and challenges associated with accessing NIR-II emissive conjugated materials for bright NIR-II fluorescence bioimaging are briefly discussed, and the significance and future prospects of these materials are proposed to offer helpful guidance for the development of NIR-II emissive materials.

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“…Compared to carbon and oxygen atoms, the sulfur atom has a larger atomic radius, indicating its greater capability for delocalizing electrons. [20] Moreover, the sulfur atom has lower electronegativity than oxygen, resulting in the lower polarizability of 3EHTT compared to EDOT and 3EHT. In the TSEH molecule, the positive charge (+ 0.24 e) on the side chain of the thiophene bridge unit and the negative charge (À 0.66 e) on the BBTD unit exactly forms one more electrostatic lock, effectively preventing the rotation of the single bond between the thiophene bridge unit and the BBTD unit.…”

Section: Molecular Design and Synthesismentioning

confidence: 99%

Unlocking the NIR‐II AIEgen for High Brightness through Intramolecular Electrostatic Locking

Wang,

Yang,

Jiang

et al. 2024

Angewandte Chemie

Self Cite

0

View full text Add to dashboard Cite

Fluorescent imaging and biosensing in the near‐infrared‐II (NIR‐II) window holds great promise for non‐invasive, radiation‐free, and rapid‐response clinical diagnosis. However, it’s still challenging to develop bright NIR‐II fluorophores. In this study, we report a new strategy to enhance the brightness of NIR‐II aggregation‐induced emission (AIE) fluorophores through intramolecular electrostatic locking. By introducing sulfur atoms into the side chains of the thiophene bridge in TSEH molecule, the molecular motion of the conjugated backbone can be locked through intramolecular interactions between the sulfur and nitrogen atoms. This leads to enhanced NIR‐II fluorescent emission of TSEH in both solution and aggregation states. Notably, the encapsulated nanoparticles (NPs) of TSEH show enhanced brightness, which is 2.6‐fold higher than TEH NPs with alkyl side chains. The in vivo experiments reveal the feasibility of TSEH NPs in vascular and tumor imaging with a high signal‐to‐background ratio and precise resection for tiny tumors. In addition, polystyrene nanospheres encapsulated with TSEH are utilized for antigen detection in lateral flow assays, showing a signal‐to‐noise ratio 1.9‐fold higher than the TEH counterpart in detecting low‐concentration antigens. This work highlights the potential for developing bright NIR‐II fluorophores through intramolecular electrostatic locking and their potential applications in clinical diagnosis and biomedical research.

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3,4-Ethylenedithio thiophene donor for NIR-II fluorophores with improved quantum yields

Abstract: Bright fluorophores are vital for bioimaging in the second near-infrared (NIR-II, 1500-1700 nm) window. Donor engineering has been demonstrated effective to significantly improve the brightness of donor-acceptor-donor (D-A-D) NIR-II fluorophores....

Cited by 5 publications

References 37 publications

Unlocking the NIR‐II AIEgen for High Brightness through Intramolecular Electrostatic Locking

Unlocking the NIR‐II AIEgen for High Brightness through Intramolecular Electrostatic Locking

Brightness Strategies toward NIR-II Emissive Conjugated Materials: Molecular Design, Application, and Future Prospects

Unlocking the NIR‐II AIEgen for High Brightness through Intramolecular Electrostatic Locking

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