Estudio teórico de las propiedades estructurales y electrónicas de los compuestos macrocíclicos R-pirogalol4arenos.

摘要

In this work, we report a theoretical study on the structural and electronic properties of the rccc and rctt conformers of several pyrogallol[4]arenes, R-Pyg[4]arenes (i.e., R = fluroethyl, methyl, t-butyl, phenyl, tolyl, and p-fluorophenyl) carried out by employing the HF-DFT hybrid B3LYP functional. Comparison of the B3LYP energies of the two stereo-isomers showed that the rccc conformer is more stable than its rctt counterpart for all the derivatives considered. However, calculations performed with the double-hybrid Grimme’s B97D functional confirmed the experimental observation that the relative stability depends upon the type of the R substituents. These results clearly suggest that the B97D functional together with large enough basis sets (i.e., split-valence plus polarization and diffuse functions) is sufficiently accurate for the purpose of describing the conformational features of these compounds. Computed electrostatic potential maps of the rccc of the different R-Pyg[4]arenes showed that a negative potential is present within the cavity of these compounds. In addition, it is observed that the size of this negative electrostatic potential depends on the electron-donating or electron-withdrawing character of the R substituents.