Halochromic Phenolate Perylene Bisimides with Unprecedented NIR Spectroscopic Properties

摘要

Organic π -conjugated dyes with strong absorptions in the near-infrared (NIR) region have received increasing attention in the past decades owing to their highly interesting but less studied electrical/optical properties and foreseeable applications in NIR light-emitting diodes, biosensing, photovoltaic cells, and telecommunication. The most prevalent organic dyes such as cyanines, squaraines, Bodipys, porphyrins, phthalocyanines, and rylenes are absorbing in the visible region of light, and common strategies to achieve a bathochromic shift of the absorption maximum of a dye are the incorporation of donor and acceptor groups into the parent chromophore and the extension of the π system of the chromophore. The introduction of both donor and acceptor substituents into the parent chromophore leads to charge transfer (CT) bands in the long-wavelength region of the absorption spectrum, which is a simple but promising strategy to achieve long-wavelength absorbing dyes. On the other hand, the extension of the π system of the chromophore is more elaborate and is often accompanied by decreased chemical stability, for example, for cyanine and squaraine dyes, or poor solubility, for example, for porphyrin, phthalo-cyanine, and rylene bisimide dyes, thus limiting their scope for applications.