6-JOE has similar absorption and emission spectra to those of rhodamine 6G, and its SE is predominantly used in automated DNA sequencing. It is also used to label nucleotides.
Figure 1. Chemical structure of 6-JOE, SE [6-Carboxy-4',5'-dichloro-2',7'-dimethoxyfluorescein, succinimidyl ester] *CAS#: 113394-23-3*