Analysis of the molecular electrostatic potential of the chemical reactivity of p-nitrophenol, p-aminophenol and p-methylphenol by the quantum method

Abstract

There are many methods in quantum chemistry such as semi-empirical methods, ab initio methods, and density functional methods. All of these methods can determine the atomic molecular properties. In this work, we chose the density functional method (DFT) to determine electrostatic potential, frontier molecular orbitals (FMO), and optimization of molecules such as p-nitrophenol, p-methylphenol, and p-aminophenol. The determination of interatomic distances, nonlinear optical descriptors (NLO) such as dipole moment (μ), polarizability (α), first hyperpolarizability (β) and second hyperpolarizability (γ). The analysis of the potential energy surface was carried out by the density functional theory (DFT) method using the Becke, Lee, Yang, and Parr Gradient Corrected Functional (B3LYP) exchange and correlation with the standard base 6-311G (d, p). This method is implemented in the program Gaussian 09. The results of the energy gap, chemical hardness, dipole moment, and hyperpolarizability show that p-nitrophenol is the reactive molecule, and p-aminophenol is the stable molecule. The electrophilic attack occurs at the O7, O10, and O9 sites for p-nitrophenol, O7 for p-methylphenol, and O7, N13 for p-aminophenol.