What is "merocyanine"

n. (context organic compound English) Any of a class of fluorescent dyes, some of which are notable for their solvatochromatic properties.

Merocyanines are a class of fluorescent dyes typified by merocyanine I.

These dyes are usually intensely colored and have large extinction coefficients.

Merocyanine 540 was the first fluorescent dye used for measuring membrane potential, while Brooker's merocyanine and related compounds are notable for their solvatochromatic properties.