Synthesis of Coumarin based fluorescent chemosensors and investigation of their photophysical properties

Coumarin ring is heterocyclic compound with different properties such as superior photophysical and biological activity with high quantum yields and broad Stokes shifts. It is known that in systems in which electron attracting/donating groups are attached to different positions of the coumarin ring, the fluorescence properties are increased by increasing the intramolecular charge transfer and when the anions are activated, the anions in the medium are detected by fluorescence decrease/increase. In this study, amide, urea, sulfonamide compounds containing the coumarin ring as the fluorophore group were synthesized, the structure of these compunds characterized with using 1H-NMR, 13C-NMR, FT-IR, HR-MS. In order to determine the photophysical properties of the synthesized compounds, absorption and emission spectra were investigated in solvents with different polarities, quantum yields and Stokes shifts were calculated. The thermal stability of the compounds was determined by Thermal Gravimetric Analysis (TGA) measurements. In addition, the sensitivity/selectivity properties of the compounds to various anions were investigated by spectrophotometric, spectrofluorimetric and 1H NMR titration method.