The study introduces a novel class of small-molecule dyes with near-infrared (NIR) emission, which are promising for biophotonics applications. These dyes, based on aminofluorene (AF) structures, exhibit ground-state antiaromaticity, leading to a narrow HOMO-LUMO gap and enhanced photostability. The AF dyes have molecular weights ranging from 299 to 504 Da and cover a spectral range from 700 to 1600 nm. They are cell-permeable and rapidly cleared by the kidneys, making them suitable for renal injury diagnosis. The dyes show ultrafast excited-state dynamics and high photostability, with rapid internal conversion from the excited state to the ground state. In vivo studies demonstrate their potential for multispectral fluorescence and optoacoustic imaging, as well as for sensing intracellular reactive oxygen species (ROS) and detecting peroxynitrite (ONOO-). The AF dyes offer advantages in cell permeability, photostability, and pharmacokinetic tuning, making them valuable tools for advanced biophotonics applications.The study introduces a novel class of small-molecule dyes with near-infrared (NIR) emission, which are promising for biophotonics applications. These dyes, based on aminofluorene (AF) structures, exhibit ground-state antiaromaticity, leading to a narrow HOMO-LUMO gap and enhanced photostability. The AF dyes have molecular weights ranging from 299 to 504 Da and cover a spectral range from 700 to 1600 nm. They are cell-permeable and rapidly cleared by the kidneys, making them suitable for renal injury diagnosis. The dyes show ultrafast excited-state dynamics and high photostability, with rapid internal conversion from the excited state to the ground state. In vivo studies demonstrate their potential for multispectral fluorescence and optoacoustic imaging, as well as for sensing intracellular reactive oxygen species (ROS) and detecting peroxynitrite (ONOO-). The AF dyes offer advantages in cell permeability, photostability, and pharmacokinetic tuning, making them valuable tools for advanced biophotonics applications.