Synthesis, Structural, and Theoretical Studies of Quinazoline-2,4-dione Derivatives

New quinazolin-2,4-dione derivatives have been synthesized and fully characterized. The new derivatives were synthesized using 3-(2-imino-4-oxo-3H,4H,5H-thiazolidin-3-yl)-1H-quinazolin-2,4-dione by nucleophilic addition mechanism. DFT calculations using B3LYP/6–311++G(d,p) level of the theory were used to investigate the molecular structures and the relative stabilities of the anticipated isomers (E and Z). Both experimental and theoretical calculations confirmed the higher stability of the Z-isomers compared to the E-isomers. The former is stabilized by two intramolecular hydrogen bonds compared to only one in the latter isomer. The frontier orbital calculations (HOMO and LUMO), and the energy gap confirmed the stability of the molecules.