Effect of donor and acceptor groups on radical scavenging activity of phenol by density functional theory

Ground state geometries of Phenol, p-nitrophenol, p-fluorophenol, p-methylphenol, p-methoxyphenol, p-aminophenol, p-hydroxybenzonitrile, 1-(4-hydroxy-phenyl)-ethanone, p-hydroxybenzoic acid and p-dimethylaminophenol have been optimized by using the density functional theory (DFT) at four different levels of theories; B3LYP/6-31G∗, B3LYP/6-31+G∗, B3LYP/6-311G∗ and B3LYP/6-311++G∗∗. The frequencies and charged species of all the investigated compounds have been calculated at the same level of theories. To explain the molecular properties energy gap, electronegativity (χ), hardness (η), electrophilicity (ω), softness (S) and electrophilicity index (ωi) have been computed. Hydrogen atom transfer and one-electron transfer mechanisms have been discussed to shed light on the radical scavenging activity.