New solvatochromic merocyanine dyes based on Barbituric acid and Meldrum's acid

Two new types of solvatochromic merocyanine dyes derived from either Meldrum's acid or Barbituric acid have been synthesized by the condensation of 4-((2-hydro xyethyl)(methyl)amino) benzaldehyde with 5-(2,6-dimethyl-4H-pyran-4-ylidene) Meldrum's acid and 5-(2,6-dimethyl-4H-pyran-4-ylidene) Barbituric acid, respectively. The solvatochromic responses of the merocyanine dyes in 22 solvents of widely different polarities were measured; positive solvatochromism, with a large absorption bathochromic shift, was observed on moving from xylene to DMSO, corresponding to their maximum fluorescence emission with a large bathochromic shift. The dyes have the potential for the development of efficient probes for the detection of volatile organic compounds.