Fluorescent Schiff Bases with Phenothiazine and Coumarin Moieties: Synthesis, Characterization, Photophysical,...

We present the design and synthesis of four new schiff bases viz., two each of phenothiazine and coumarin derivatives. The structures were proposed based on FT-IR, ¹H NMR, ¹³C NMR and mass spectral data. The photophysical, solvatochromic and electrochemical studies of all the compounds were carried out. Furthermore, theoretical studies such as density functional theory (DFT) were carried out to gain a better understanding of the compounds' intramolecular charge transfer properties and electronic structures. Good agreement was noticed between the HOMO-LUMO energy gap obtained from DFT studies and that calculated from absorption threshold wavelengths. All the compounds showed Stokes shifts in the range of 6345-11,405 cm^-1. These findings showed that the new schiff bases could be considered as attractive candidates for use in the development of OLEDs, organic electrical devices and optoelectronic devices. Newly synthesized compounds were tested for biological activities. When compared to conventional standards, gallic acid and indomethacin, the schiff bases showed better antioxidant and antiinflammatory activities, respectively.