Used in oligonucleotide synthesis to introduce a fluorescent label during the solid-phase synthesis of DNA or RNA. The phosphoramidite group enables efficient coupling to the growing nucleic acid chain, while the tetrachlorofluorescein moiety provides strong fluorescence for detection and imaging applications. Commonly applied in the production of fluorescent probes, molecular beacons, and labeled primers for real-time PCR, sequencing, and hybridization studies. Its high sensitivity allows for trace-level detection in diagnostic assays and cellular imaging.