Crystal structure of (E)-N′-benzylidene-2-methoxybenzohydrazide

In the title benzoylhydrazide derivative, C15H14N2O2, the dihedral angle between the planes of the two phenyl rings is 12.56 (9)°. The azomethine double bond adopts an E configuration stabilized by an N—H...O hydrogen bond. In the crystal, the components are linked by C—H...O interactions to form chains along the b axis

Antioxidant properties of phenolic Schiff bases: structure-activity relationship and mechanism of action.

International audiencePhenolic Schiff bases are known for their diverse biological activities and ability to scavenge free radicals. To elucidate (1) the structure-antioxidant activity relationship of a series of thirty synthetic derivatives of 2-methoxybezohydrazide phenolic Schiff bases and (2) to determine the major mechanism involved in free radical scavenging, we used density functional theory calculations (B3P86/6-31+(d,p)) within polarizable continuum model. The results showed the importance of the bond dissociation enthalpies (BDEs) related to the first and second (BDEd) hydrogen atom transfer (intrinsic parameters) for rationalizing the antioxidant activity. In addition to the number of OH groups, the presence of a bromine substituent plays an interesting role in modulating the antioxidant activity. Theoretical thermodynamic and kinetic studies demonstrated that the free radical scavenging by these Schiff bases mainly proceeds through proton-coupled electron transfer rather than sequential proton loss electron transfer, the latter mechanism being only feasible at relatively high pH