New pyrene and fluorene-based π-conjugated Schiff bases: Theoretical and experimental investigation of optical properties

Abstract

The new Schiff bases with D-?-A system were synthesized from the reaction of polycyclic aldehydes and substituted benzothiazoles. The structure of the synthesized Schiff bases (7a and 9a) was determined by FT-IR, 1H NMR, 13C NMR, ESI-Mass and elemental analyses. The optical properties of the new compounds were investigated and the optical band gaps (Eg) were calculated by the Tauc method using the UV-Vis absorption spectra. Density Functional Theory (DFT/B3LYP/6-31 G (d, p)) calculations were conducted to get more insight on the structural and electronic properties of novel Schiff bases. The optimized molecular geometry, UV-Vis spectroscopic parameters and HOMO-LUMO energies were examined and the calculated results were compared with experimental data.