Novel efficient fluorophores synthesized from citric acid

A series of novel fluorescent compounds was isolated from condensation mixtures of citric acid and specific beta-amines. Their chemical structure was determined using H-1, C-13 and HSQC experiments, elemental analysis data, high resolution and fragmentation spectra ESI-MS analyses. These compounds consisted of five-membered ring fused 2-pyridones. The fluorophores exhibited quantum yields as high as 79%.