Synthesis and characterisation of methine dyes derived from condensation of 4-nitrophenylacetonitrile with aromatic aldehydes

A range of methine dyes has been synthesised by condensation of electronegative active methylene compound, 4-nitrophenylacetonitrile with substituted benzaldehydes. The electronic absorption spectroscopic properties of the dyes were investigated. It was found that in general, substituents on the aromatic aldehyde moiety had a significant effect on the visible absorption maxima of the dyes.