Used as a key intermediate in the synthesis of fluorescent dyes and xanthene-based dyes such as fluorescein and rhodamine derivatives. It plays an important role in the development of pH indicators and biological stains due to its ability to form highly conjugated structures upon further chemical modification. Also employed in the preparation of photochromic materials and sensors for metal ion detection. Its carboxylic acid group allows for easy functionalization, making it valuable in bioconjugation chemistry and the development of fluorescent probes for imaging in biological systems.