Hiperpolarizabilidade molecular de segunda ordem e HOMO-LUMO de derivados de cumarinas e neolignanas

Abstract

In this work the results for the dipole moment (𝜇), the mean linear polarization (𝛼) and the second average hyperpolarizability (𝛾), static and dynamic of crystals 2-(4- nitrophenoxy)-1-phenylethanone (𝑵𝑭 − 𝑭𝑬) and Acetyl-6-bromocoumarin (𝑨𝑩𝑪) under the effect of the crystalline environment. The polarization effects of the crystalline environment were inserted through the supermolecule (𝑆𝑀) approach, together with the iterative process of electrostatic polarization, which is based on the convergence of the dipole moment. The dipole moment was determined by the methods Møller-Plesset Perturbation Theory (𝑀𝑃2) and Density Functional Theory (𝐷𝐹𝑇), using the basic set of functions 6 − 311 + 𝐺(𝑑). The density functional 𝐵3𝐿𝑌𝑃, 𝐶𝐴𝑀 − 𝐵3𝐿𝑌𝑃, 𝐵𝐻𝑎𝑛𝑑𝐻𝐿𝑌𝑃, 𝑀062𝑋, 𝑀06𝐻𝐹 and 𝑊𝐵97 were tested, the latter two of which presented the values of the dipole moment with the smallest percentage difference when compared to the results obtained via 𝑀𝑃2. In addition, the 𝐻𝑂𝑀𝑂 − 𝐿𝑈𝑀𝑂 energies, an important parameter related to the excitation properties of the compounds, were calculated. By means of the HOMO-LUMO energies, it was possible to estimate values of the following properties: electronic chemical potential (𝜇𝑐𝑝), chemical hardness (𝜂), ionization energy (𝐸𝐼 ) and electron affinity (𝐴𝐸). Regarding the effects of the crystalline environment, the two compounds were very sensitive, especially with respect to the dipole moment and the second average hyperpolarizability.