Synthesis and characterization of dyes exemplified by 2-arylidene-1-dicyanomethyleneindane

The synthesis of methine dyes formed by Knoevenagel condensation of aromatic aldehydes with 1-dicyanomethylene indane 2 afforded a novel series of dyes absorbing in the region 490 ¯593 nm. Substituents on the aromatic aldehyde moiety have a significant effect on the visible absorption maxima of the dyes; increasing the solvent polarity also had a pronounced effect on the absorption maxima.