Phenalenone fluorophores-synthesis, photophysical properties and DFT study.

Three new fluorescent phenalenone derivatives incorporating bexozazolyl, benzothiazolyl and benzimidazolyl rings have been synthesized from the intermediate 3-(1,3-benzazol-2-yl) naphthalen-2-ol by reacting with glycerol. The synthesized phenalenone derivatives were well characterized by using FT-IR, (1)HNMR, (13)CNMR and Mass spectroscopy. The photophysical properties of these phenalenone derivatives show that these dyes absorb in the range of 300-429 nm and emitted in the range of 348-578 nm. The relative fluorescence quantum yields of these derivatives were determined by using fluorescein, tinopal and anthracene as the reference standards. Photophysical properties of the synthesized phenalenone dyes were evaluated by UV-Visible spectroscopy and compared with the computed vertical excitations obtained from TD-DFT. Thermal stability of the compounds were studied by using thermo gravimetric analysis and results show that compounds are thermally stable up to 298-347 °C.