2, 1, 3‐Benzothiadiazole Derivative Small Molecule Fluorophores for NIR‐II Bioimaging

Abstract Second near‐infrared (NIR‐II) bioimaging technology shows broad application prospects in the field of biomedical due to its significant superiority in deep tissue penetration and high signal‐to‐background ratio. Among them, organic small molecule fluorophores have received progressively more consideration due to their low biotoxicity, high biocompatibility, rapid clearance, and good modification properties. As the key acceptor core, 2, 1, 3‐benzothiadiazole (BTD) derivative plays an essential role in the construction of donor‐acceptor‐donor type NIR‐II fluorophores. This mini‐review summarizes the research development of NIR‐II small molecule fluorophores based on BTD derivatives in the field of bioimaging, focusing on molecular design and photophysical properties, and introduces a part of the applications in the biological field. Furthermore, the challenges of BTD‐based NIR‐II fluorophores in the future development and application are discussed .