Synthesis, and Fluorescence Properties of Coumarin and Benzocoumarin Derivatives Conjugated Pyrimidine Scaffolds for Biological Imaging Applications

Series of coumarin and 5,6-benzomcomarin substituted pyrimidine derivatives 11–15 and 22–25 were synthesized, aiming to develop new imaging fluorescent agents. Analogously, treatment of 4-chloropyrimidine analog 16 with coumarin 3-carbohyrazide 5 under MWI condition followed by boiling with NH4OAc in HOAc furnished coumarin-1,2,4-triazolo-pyrimidine analog 18. The fluorescence property was investigated spectrophotometrically in MeOH with Rhodamine 6G as standard dye. All the compounds showed emission in the region between 331 and 495 nm. The quantum yield of all the compounds were found to be weak, except methyl benzocoumarin 3-carboxylate 22 which showed (ΦF = 0.98) in comparison to Rhodamine 6G as standard (ΦF = 0.95).