Estudo computacional de nanoestruturas de ouro funcionalizadas com moléculas orgânicas quirais

Abstract

In this present work was carried out the computational study of the functionalization of gold nanoparticles in spherical shape with L-amino acids using molecular dynamics simulations and geometry optimizations at DFTB level (Density Functional Tight-Binding) using Hamiltonian GFN1-xTB and phase space scanning through classic calculations to determine initial configurations. A determination of the ini- tial configurations performed using phase space scanning, it turned out that the L-amino acids have a tendency to interact on the nanostructure in the face (111) and low tendency to interact with the face (110). Simulations of semi-empirical quantum molecular dynamics of structure corresponding to the global minimum showed that there is a preference of the L-amino acids in interacting with the AuNP through the sites carbonylic and chiral carbon amino as well as the nitrogenated sites existing in their side chain which occurs for arginine, lysine and histidine. The interactions between AuNP and L-amino acids are covalent but of low intensity. confirmed by resorting to the analysis of the surface of the molecular orbitals and Wiberg binding orders of the structures. The adsorption of amino acids on the surface of the AuNPs presented chiral responses, confirmed by the calculation of the spectrum of electronic circular dicroysm and dissimetric factor g (g-factor) and HCM (Medida de quiralidade de Hausdorff). Which demonstrates that the amino acids are capable of inducing chirality in the AuNP. The intensity varies depending on the amino acid used, however, phenylalanine, tryptophan, lysine, arginine, histidine and aspartate and glutamic acids are the ones that most induce chirality in the system.