DFHBI-BI is an analog of the green fluorescent protein chromophore. It can bind to Broccoli (a fluorescent RNA aptamer) and is activated by this interaction, exhibiting higher binding affinity. In mammalian cells, DFHBI-BI prevents thermal denaturation of Broccoli at 37°C, thereby increasing the formation of Broccoli-BI complexes with fluorescent properties. Its fluorescence wavelength is 559/635 nm.