Fluoran is a

triarylmethane dye Triarylmethane dyes are synthetic organic compounds containing triphenylmethane backbones. As dyes, these compounds are intensely colored. They are produced industrially as dyes. Families Triarylmethane dyes can be grouped into families accordin ...

. It is the structural core of a variety of other dyes. These dyes have a variety of applications such as chemical stains (for example

eosin Eosin is the name of several fluorescent acidic compounds which bind to and form salts with basic, or eosinophilic, compounds like proteins containing amino acid residues such as arginine and lysine, and stains them dark red or pink as a resul ...

s) and in

thermal paper A thermal column (or thermal) is a rising mass of buoyant air, a convective current in the atmosphere, that transfers heat energy vertically. Thermals are created by the uneven heating of Earth's surface from solar radiation, and are an example ...

. Black 305 is a common leuco dye product for thermal paper. Eosin

References

Triarylmethane dyes Spiro compounds Lactones {{organic-compound-stub