Used as an intermediate in the synthesis of fluorescent dyes and optical brighteners due to its ability to form rigid, conjugated structures that enhance photoluminescence. Also employed in the development of sensors for metal ions, where the carboxylic acid group allows for coordination with cations, resulting in detectable changes in optical properties. Additionally, it serves as a building block in the preparation of specialty polymers and pharmaceuticals, where the imide and carboxylic acid functionalities enable further chemical modifications.