Fulgide

In organic chemistry, a fulgide is any of a class of photochromic compounds consisting of a bismethylene-succinic anhydride core that has an aromatic group as a substituent.

It can undergo reversible photoisomerization induced by ultraviolet light, converting between the E and Z isomers, both of which are typically colorless compounds.

It has nearly the same photochromic properties, but the imide is substantially more stable than the carboxylic acid anhydride towards hydrolysis.

[5] Fulgenolide is a lactone analog: one of the two succinic anhydride carbonyl groups is replaced by an alkyl link.

Fulgenolides have a larger quantum yield than other fulgide derivative and has a λmax of the C form in near IR-region.