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

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

Theoretical analysis of the Reactivity of phenol substituted in the para position by halides by the functional theory of density

Theoretical developments have made it possible to make quantum physics applied to chemistry an essential tool associated with experimental chemistry. Two avenues have emerged for this development: one addresses the problems by describing systems by a wave function; the other does so by its electron density. In this work, we studied the quantum method of the density functional theory (DFT) B3LYP / 6-311G (d, p) to determine the various quantum chemical descriptors and the optimization of the different molecules: p-bromophenol, p-fluorophenol and p-chlorophenol. The study of the global reactivity of molecules is based on the calculation of global indices deduced from electronic properties, such as ionization potential (I), Electronic affinity (A), chemical hardness (η)., Electronegativity x. and Overall softness (σ), Maximum charge transfer (ΔNmax), Overall electrophilicity (ω). Besides, we worked on nonlinear optical descriptors (NLO) such as the dipole moment (μ), the polarizability (α), the first hyperpolarizability (β), and the second hyperpolarizability (γ). To check the stability of the molecules we determined the 3D maps of the HOMO and LUMO orbitals, the Mulliken charges of each molecule, the electrostatic potential, the lengths, and the bond angles of the molecules of p-bromophenol, p-fluorophenol, and p-chlorophenol