The structure of the ortho-, meta- and para- hybrid diindolylmethane-phenylboronic acids and their interactions were optimized with by a quantum chemical method, using density functional theory at the (DFT) level. Thus, infrared bands were assigned based on the scaled theoretical wavenumbers by correlating the respective experimental data of the molecules. In addition, the corresponding ¹H-/13C-/11B-NMR experimental and theoretical chemical shifts were correlated. The target molecules showed a poor treatment of the OH shifts in the GIAO method due to the absence of explicit solvent effects in these calculations; therefore, they were explicitly considered with acetone molecules. Moreover, the electron density at the hydrogen bond critical point increased, generating stabilization energy, from weak to moderate or weak to strong, serving as an indicator of the strength of the hydrogen bond between the different intermolecular interactions. Finally, some properties related to the reactive behavior of the target molecules associated with their cytotoxic effects and metabolic pathways were also calculated.
Keywords: DFT calculations; boronic acids; diindolylmethane; hydrogen bonds; spectroscopy.