Cyanine dyes

Summary

• 1. Starting from N-arylquinolinium salts, twelve new symmetrical carbocyanines having phenyl and naphthyl radicals on the hetero nitrogen have been prepared.

• 2. It has been shown that the introduction of phenyl and naphthyl radicals on the hetero nitrogen of quinocarbocyanines causes a bathochromic shift in the absorption maximum, as compared with the N-ethyl compounds, of 10–12 and 14–18 mμ respectively.

• 3. Introduction of a methyl group in the meso-position of the polymethine chromephore of N-arylcarbocyanines causes an insignificant hypsochromic shift of the absorption maximum, as compared with the unsubstituted compounds.