Fluorene-9-acetic acid is primarily used in organic synthesis and research applications. It serves as a building block for the development of more complex chemical compounds, particularly in the field of medicinal chemistry. This compound is often utilized in the synthesis of pharmaceutical intermediates, where its structure can be modified to produce potential drug candidates. Additionally, it finds application in material science, where it is used to create organic semiconductors and light-emitting materials for electronic devices. Its unique properties make it valuable in the study of fluorescence and photophysical behaviors in various chemical systems.