New Schiff Base Derivatives: Preparation, Antioxidant Activity, and DFT Investigation of Structural Properties

A series of novel Schiff bases was synthesized with good yields from 2(3H)-benzoxazolone using the condensation reaction between 6-amino-2(3H)-benzoxazolones and different substituted aromatic aldehydes under refluxing ethanol in the presence of acetic acid as a catalyst. The antioxidant activity of the obtained compounds was evaluated, the control using butylated hydroxytoluene (BHT) indicates that the four synthesized compounds showed excellent free radical scavenging activity. Complementary DFT study of some spectroscopic and electronic properties of a selected product's structures was also performed within the B3LYP/6-311++G(d,p) level of theory. The molecular electrostatic potential analysis indicates that the studied compounds may be used as good reagents for electrophilic or nucleophilic attacks. Frontier molecular orbitals (FMO) analysis shows also that these structures are characterized by a low gap energy accounting for high reactivity. The reactivity indices indicate that these compounds are suitable starting materials for performing several nucleophilic or electrophilic reactions.