Synthesis and photophysical properties of a new type of merocyanine dye based on N-methyl derivatives of 4-aryl-2-(1-hydroxy-4-nitronaphthalen-2-yl)cyclopenta[b]pyridine

A simple and efficient method for the synthesis of a new type of merocyanine dye based on N -methyl derivatives of 2-(1-hydroxy-4-nitronaphtalen-2-yl)cyclopenta[ b ]pyridine by the Chichibabin method was discovered. Three ways of obtaining these systems are considered. The tautomerism and fluorescent properties of the synthesized compounds are considered depending on the structure, the polarity of medium under neutral conditions and in the presence trifluoroacetic acid. Under neutral conditions, the resulting cyclopenta[ b ]pyridines exist as several tautomeric forms, predominantly in the keto-amine. • 4-nitronaphthalen-1(2 Н )-one is a new acceptor fragment of merocyanine dyes. • A simple synthetic procedure is described. • The merocyanine form has Z-configuration of double bond between donor and acceptor. • Fluorescent properties and tautomerism depend on the structure of merocyanine. • The merocyanine form fluoresces only in toluene in the red region of the spectrum.