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Suppressing Non-Radiative Decay via Cyanation: A Promising Design Strategy for Bright Organic NIR-II Fluorophores
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DOI：10.1002/anie.202522260.png)
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Abstract
En 中文
Achieving high fluorescence efficiency in organic fluorophores within the second near-infrared window (NIR-II, 1000∼1700 nm) remains challenging, as extended π-conjugation and active intramolecular motions typically funnel excitation energy into non-radiative decay. Here, we present peripheral cyanation as a molecular design strategy that directly modulates excited-state dynamics and suppresses non-radiative relaxation. Incorporation of cyano groups (A') into the D-A-D scaffold of BBTCz afforded BBTCzCN with an A’-D-A-D-A’ architecture, which significantly reduced vibronic coupling compared to the parent dye. Upon encapsulation with DSPE-mPEG5000, BBTCzCN nanoparticles (NPs) retained a high FLQY of 2.8% with a record-high brightness of 565 M−1 cm−1, representing a 10.4-fold enhancement over BBTCz NPs and placing it among the brightest organic NIR-II emitters reported to date. Mechanistic studies combining density functional theory and ultrafast spectroscopy revealed that cyanation synergistically suppressed vibrational relaxation and internal conversion, thereby prolonging radiative decay pathways. As a result, BBTCzCN NPs enabled high-resolution vascular imaging, real-time lymphatic tracking, and precise intraoperative delineation of tumors and peritoneal metastases. This work establishes peripheral cyanation as a broadly applicable molecular design strategy for tailoring excited-state decay pathways, advancing the development of next-generation NIR-II fluorophores for deep-tissue imaging and image-guided surgery.
Keywords:
Cyanation
Fluorescence imaging
NIR-II Fluorophore
Non-Radiative decay
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16.9
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5.6W
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53.0W