Designing Boron and Metal Complexes to Fluoride Recognition: Computational Perspective

The fluoride anion (F−) may have beneficial or harmful effects on the environment depending on its concentration. Here, we shed light into the F− recognition by compounds containing boron, tellurium and antimony, which experimentally demonstrated to be capable of interacting with the ion F− in a partially aqueous medium. The boron and metal complexes recognize the anion F− from an electrostatic principally energy, but with an importantly contribution of the orbital interactions energy. Since that the natural orbitals for chemical valence (NOCV) methodology indicates that the main orbital interactions behind the fluoride recognition are σ bonds between the receptors and the anion F–. The charged receptors, which provide: i) two B atoms; ii) one B atom and one Sb atom; and iii) one B atom and one Te atom, to directly interact with the ion F− appear as one of the best structures to anionic recognition of F−. It is supported by combination of favorable electrostatic and σ bond interactions. Overall, the presence of electron donor groups, such as, –CH3 and –OH, in the receptors structure destabilizes the fluoride recognition because decrease the attractive electrostatic energy and increase the Pauli repulsion energy in the receptor….F– bonds. Notably, electron acceptor groups as, for example, –CN and –NO2 in the receptors structure favor the interaction with the ion F–, due to improving of the electrostatic and σ bond interactions. This study opens the gates to find the main features of a receptor able to F– recognition.