Synthesis and photophysical properties of novel bis-quinolin-3-yl-chalcones

A novel series of unsymmetrical bis-quinolin-3-yl chalcones has been synthesized under visible light using a Claisen-Schmidt condensation reaction between the 2-(morpholine-piperidine-pyrrolidine-thiomorpholine) substituted quinoline-3-carbaldehyde and 1-(2-methyl-4-phenylquinolin-3-yl) ethan-1-one derivatives, conducted at room temperature in the presence of NaOH/EtOH. The structures of the synthesized compounds have been confirmed by NMR spectroscopy and high-resolution mass spectroscopy. The synthesized compounds exhibit lambda max values ranging from 215 nm to 290 nm in non-polar to polar solvents, demonstrating positive solvatochromism. Compounds containing nitro group substituent exhibit a significant blue shift owing to their strong electron-withdrawing ability, which also contributes to fluorescence quenching. Geometrical optimization and the calculation of HOMO, LUMO, and energy gap are calculated by using the DFT/B3LYP/6-31G(d) method. A novel synthesis of unsymmetrical bis-quinolines via Claisen-Schmidt condensation reaction.