Abstract

Cyanine dyes and the related merocyanines and oxonols are commercially important dyes for high technology uses, including spectral sensitization of photographic films, optical filtering/light modulation, dye lasers, and biological staining agents. The primary chromophores and heterocycles in these dyes are outlined with specific reference to chemical reactions that allow the synthesis of almost every type of cyanine and related dye. Known structure–property relationships for the cyanines are extensive, and examples are included for properties such as color, substituent effects, solubility, self-association (aggregation), electrochemical behavior, photochemical reactions, and biological uses.