Tsai Yi-Chen, Chen Yan-Chang, Lu Hsiu-Feng, Chan Kai-Min, Lin Syue-Liang, Lin Pin-Xuan, Rotomskis Ricardas, Steponkiene Simona, Wu Tung-Kung, Chan Ming-Hsien, Ho Ja-An Annie, Huang Yu-Fen, Hsu Chao-Ping, Chan Yang-Hsiang
Department of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan, R.O.C.
Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan, R.O.C.
J Am Chem Soc. 2025 Jun 25;147(25):21940-21949. doi: 10.1021/jacs.5c05151. Epub 2025 Jun 11.
NIR-II fluorophores (1000-1700 nm) are pivotal for biomedical imaging, offering deep-tissue penetration and high signal-to-noise ratios but suffer from low quantum yields (QY < 0.01%) beyond 1200 nm. To date, most reported NIR-II small-molecule dyes are derived from polymethine and xanthene frameworks. However, achieving NIR-II chromophores with sufficient QYs remains challenging, as the energy gap law dictates that internal conversion-governed by the emission energy gap and reorganization energy-dominates nonradiative decay. To address this, we designed a novel pseudo-2D molecular framework: 34 π-electron annulated porphyrinoids (Scheme 1), engineered to minimize reorganization energy. These structures achieve emission wavelengths up to 1290 nm with QYs of 1.10-6.14%. Density functional theory (DFT) calculations were performed to unravel the photophysical mechanisms underlying these behaviors, showing that the reorganization energy is as small as 10.5 meV for these dyes, which validates our design. The optimized molecular structures and the stacking geometry of these porphyrinoids in the nanoparticle form were also elaborated by DFT. The intense NIR-II fluorescence (>1200 nm) enables high-resolution in vivo vascular imaging, further enhanced by AI-driven imaging algorithms to significantly improve image quality.
近红外二区荧光团（1000 - 1700纳米）对生物医学成像至关重要，具有深层组织穿透能力和高信噪比，但在1200纳米以上存在量子产率低（量子产率<0.01%）的问题。迄今为止，大多数报道的近红外二区小分子染料源自聚甲炔和呫吨骨架。然而，要获得具有足够量子产率的近红外二区发色团仍然具有挑战性，因为能隙定律表明，由发射能隙和重组能主导的内转换决定了非辐射衰变。为了解决这个问题，我们设计了一种新型的准二维分子框架：34个π电子稠合卟啉类化合物（方案1），旨在将重组能降至最低。这些结构实现了高达1290纳米的发射波长，量子产率为1.10 - 6.14%。进行了密度泛函理论（DFT）计算以揭示这些行为背后的光物理机制，结果表明这些染料的重组能低至10.5毫电子伏特，这验证了我们的设计。DFT还阐述了这些卟啉类化合物在纳米颗粒形式下的优化分子结构和堆积几何形状。强烈的近红外二区荧光（>1200纳米）实现了高分辨率的体内血管成像，并通过人工智能驱动的成像算法进一步增强，从而显著提高图像质量。
