A computational investigation on the structure, global parameters and antioxidant capacity of a polyphenol, Gallic acid.

A computational DFT-B3LYP structural analysis of a poly phenol, Gallic acid (GA) has been performed by using 6-311++ G (df, p) basis set. The GA is a relatively stable molecule with considerable radical scavenging capacity. It is a well known antioxidant. The NBO analysis shows that the aromatic system is delocalized. The results reveal that the most stable radical is formed at O3-atom upon scavenging the free radicals. Global descriptive parameters show that GA acts as an acceptor center in charge transfer complex formation which is supported by ESP and contour diagrams and also by Qmax value. The GA is a good antioxidant and it can be better understood by HAT and TMC mechanisms as it has low BDE, ΔHacidity and ΔGacidity values. The ΔBDE and ΔAIP values also confirm that the antioxidant capacity of GA can be explained through HAT rather than the SET-PT mechanism.