RESUMEN
Molecular mechanics and quantum mechanics were used to study the preferred conformations, electron densities and frontier orbitals of d-LSD and their analogs with the isopropyl amide group, compounds with reported activity over the serotonin receptor. Electron densities and frontier orbitals for isopropyl analogs were similar to d-LSD, so these properties can not be related with the changes in biological activity previously reported. It was found that isopropyl analogs have preferred conformations similar to d-LSD with small variation in the alkylamide group. The variation in the alkylamide group causes small variations in the orientation of the carbonyl amide group, our study suggests that this variation could affect the binding with the hydrophobic region of the receptor.