2-oxo-2H-chromen-3-yl Propionate and 2-oxo-2H-chromen-3-yl Acetate: Short-step Synthesis, Characterization and Fluorescence Properties

Abstract

Natural or synthetic coumarins are of great interest, since many of them show prominent biological activity and photochemical characteristics. In particular, hydroxycoumarins and their derivatives have been extensively studied in various fields such as biology, medicine, physics and chemistry. Among the well-known compounds is 7-hydroxycoumarin, also known as umbelliferone and 4-hydroxycoumarin. Against 3-hydroxycoumarin and its derivatives are less known and studied. In this study, new acyl derivatives were synthesized from 3-hydroxycoumarin or chromen-2,3-dione its tautomeric form and chloride acid in the presence of an appropriated base. The structures of the newly obtained compounds were confirmed by elemental analysis, mass spectrometry (MS), IR and NMR spectrometry and X-ray diffractometry. In addition, the fluorescence properties of the titre compounds were also studied in both liquid and solid state. In liquid media, the study concerned their behaviour in fluorescence emission spectrometry in 6 solvents of different polarities. The new heterocyclic compounds have been successfully synthesized. Fluorescence spectrum analyses show that these compounds are all fluorescent in both solid and liquid state with varying fluorescence intensities (I_F). On solvatochromic analyses, it appears that the behaviour of the spectrum depends strongly on the solvent. The fluorescence intensity and wavelength (λem) vary depending on the nature of the substituent (R) and especially that of the solvent. It should also be noted that chloroform is the solvent that most enhances the fluorescence of the compounds.