McAuliffe Katherine J, Kaster Megan A, Szlag Regina G, Trivedi Evan R
Department of Chemistry, Oakland University, Rochester, MI 48309, USA.
Int J Mol Sci. 2017 Jun 1;18(6):1177. doi: 10.3390/ijms18061177.
Boron subphthalocyanines (SPcs) are aromatic macrocycles that possess a combination of physical and optical properties that make them excellent candidates for application as fluorescent imaging probes. These molecules have intense electronic absorption and emission, and structural versatility that allows for specific tuning of physical properties. Herein, we report the synthesis of a series of low-symmetry fluorinated SPcs and compare them to analogous compounds with varying numbers of peripheral fluorine atoms and varied aromaticity. Across the series, with increasing addition of fluorine atoms to the periphery of the ring, a downfield chemical shift in F NMR and a bathochromic shift of electronic absorption were observed. Expanding the size of the aromatic ring by replacing peripheral benzo- groups with naphtho- groups prompted a far more drastic bathochromic shift to absorption and emission. Fluorescence quantum yields (Φ) proved to be sufficiently high to observe intracellular fluorescence from MDA-MB-231 breast tumor cells in vitro by epifluorescence microscopy; fluorination proved vital for this purpose to improve solubility. This report lays the groundwork for the future development of these promising SPcs for their ultimate application as near-infrared (NIR) fluorescent imaging probes in biological systems.
亚酞菁硼（SPcs）是芳香族大环化合物，具有多种物理和光学性质，使其成为荧光成像探针应用的理想候选物。这些分子具有强烈的电子吸收和发射特性，以及结构多样性，能够对物理性质进行特定调节。在此，我们报告了一系列低对称性氟化SPcs的合成，并将它们与具有不同数量外围氟原子和不同芳香性的类似化合物进行比较。在整个系列中，随着环外围氟原子添加量的增加，在氟核磁共振中观察到化学位移向低场移动，电子吸收发生红移。通过用萘基取代外围的苯并基团来扩大芳香环的尺寸，促使吸收和发射发生更为显著的红移。荧光量子产率（Φ）被证明足够高，能够通过落射荧光显微镜在体外观察MDA-MB-231乳腺肿瘤细胞的细胞内荧光；氟化被证明对提高溶解度至关重要。本报告为这些有前景的SPcs未来作为生物系统中的近红外（NIR）荧光成像探针的最终应用奠定了基础。
