cyanine dye
cyanine dye
Cyanine dyes are synthetic dyes with the general formula R<small><sub>2</sub></small>N[CH=CH]<small><sub><em>n</em></sub></small>CH=N<small><sup>+</small></sup>R<small><sub>2</sub></small>    ↔ R<small><sub>2</sub></small>N<small><sup>+</small></sup>=CH[CH=CH]<small><sub><em>n</em></sub></small>NR<small><sub>2</sub></small> (<em>n</em> is a small number) in which the nitrogen and part of the conjugated chain usually form part of a heterocyclic system, such as imidazole, pyridine, pyrrole, quinoline and thiazole.