Synthesis of highly fluorescent coumarinyl chalcones derived from 8-acetyl-1,4-diethyl-1,2,3,4-tetrahydro-7H-pyrano[2,3-g]quinoxalin-7-one and their spectral characteristics

A series of novel coumarin based chalcones were synthesized by the classical crossed aldol condensation reaction of 8-acetyl-1,4-diethyl-1,2,3,4-tetrahydro-7H-pyrano[2,3-g]quinoxalin-7-one and various substituted benzaldehydes. These novel ketocoumarin derivatives having a 1,4-diethyl-1,2,3,4-tetrahydroquinoxaline framework exhibited brilliant fluorescence. The novel chalcones absorbed in the range of 458–523 nm in various solvents. The wavelength of maximum absorption of these chalcones was found to be significantly longer than their simple acyl derivative known in the literature. The dyes displayed longer wavelength of absorption in the high polarity solvents compared to non-polar solvents. Thermogravimetric analysis of the chalcones revealed that the chalcones possess good thermal stability.

Graphical abstractA series of novel coumarin based chalcones were synthesized by classical crossed aldol condensation reaction. These novel ketocoumarin derivatives having 1,4-diethyl-1,2,3,4-tetrahydroquinoxaline framework exhibited brilliant fluorescence. The chalcones displayed excellent bathochromicity. These novel dyes absorbed at significantly longer wavelength than their analogues known in the literature. Thermogravimetric analysis of the chalcones revealed that the chalcones possess good thermal stability. Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Novel coumarinyl chalcones based on tetrahydroquinoxalin are reported. ► These novel ketocoumarin derivatives exhibited brilliant fluorescence. ► The absorption maxima of chalcones was significantly longer than earlier analogs. ► Thermogravimetric analysis revealed good thermal stability.