The Quantum Chemistry Study On Structures And Properties Of 5-substituted Indole Derivatives

As a kind of important medium in drugs synthesis, 5-substituted indole derivatives are attached importance increasingly. Despite of many experimental studies on 5-substituted indole derivatives, theoretical investigations are much less, therefore, it is imperative to study the structure-property relationship to explain experimental facts and to predict unkown information.In this paper, we apply Density Functional Theory (DFT) methods and Second-order Perturbation theory (MP2) of quantum chemistry to calculate 5-substituted indole derivatives at B3LYP/6-31G* B3LYP/6-311 G B3LYP/6-311G and MP2/6-31G level using the energy gradient method, respectively. We mainly study stable molecular geometries and atomic charge distributing of 5-methoxy indole 5-methyl indole and 5-chlorin indole. It is shown that a planar geometry was found to be the most stable with all atoms, other than the methoxy hydrogens for 5-methoxy indole and methyl hydrogens for 5-methyl indole. All atoms of 5-chlorin indole are in the same plane. Then harmonic vibrational frequency has been performed on the basis of geometry optimization. IR intensities corresponding with the calculated frequencies have also been shown. On the basis of a mass of calculation, we study the effects of three 5-substituted groups on structure-property of indole derivatives. These results have indicative and theoretic meaning in the directions of the study on the property, molecular design and synthesis.