带功能手柄的二苯并呫吨类染料（EC5）用于生物成像

Fluorophores in the shortwave infrared spectral region (greater than 800 nm) are currently widely used in the biomedical field. The ideal dye should be bright, highly photochemically stable, biocompatible and easy to derivatize to introduce functional groups. In this work, an NIR fluorescent dye EC5 with dual modifiable sites was developed through an efficient 5-step synthesis route using 7-bromo-2-naphthol as a raw material. The resulted compound was characterized by nuclear magnetic resonance (NMR) hydrogen spectroscopy, carbon spectroscopy, high-resolution mass spectrometry (HRMS) and X-ray diffraction (XRD). The maximum absorption and emission wavelengths of EC5 were 871 nm and 923 nm, respectively, with a high fluorescence brightness of 38715 and a fluorescence lifetime of 0.70 ns in dichloromethane. EC5 was also exhibited an excellent anti-aggregate ability with the concentration up to 100 μmol/L and a high photostability with a high-density power of 880 nm laser beam. Finally, EC5 was used for high temporal and spatial resolution fluorescence imaging of BALB/c mice as well as anti-counterfeiting writing, which demonstrated that EC5 has a wide range of application prospects in the field of near-infrared fluorescence in vivo imaging.