Molecular structure, covalent and non-covalent interactions of an oxaborole derivative (L-PRO2F3PBA): FTIR, X-ray diffraction and QTAIM approach

Boron containing compounds have gained attention in the past decades due to their potential applications as pharmaceuticals. These materials comprise molecules such as boronic acids, iminoboronates and oxaboroles. The main idea is to develop molecular units that can interact with organic compounds and biological molecules for pharmaceutical and biological applications. Herein, we report the synthesis and characterisation of (3aS,7S)-1-(2-fluoropyridin-3-yl)-1-hydroxy-3-oxohexahydro-1H-pyrrolo[1,2-c][1,3,2]oxazaborol-7-ium-1-uide, which has been obtained by the reaction of the biologically active molecule L-proline with 2-fluoro-3-pyridineboronic acid in ethanol. The compound, namely L-PRO2F3PBA hereafter, was characterised by FTIR spectroscopy, single-crystal X-ray diffraction, and quantum chemical methods based on QTAIM to study its molecular structure, covalent and non-covalent interactions. The results showed the importance of a coordinate N→B dative bond for stabilising the molecules in the solid-state. Also, the molecular self-assembly occurs mainly by N-H···O, O-H···O and C-H···O non-covalent interactions. The ESP maps analysis showed that the molecules interacted so that electropositive zones attracted the electronegative zones to form dimeric pairs. Overall, the results suggested that the compound comprises functional groups that make it a good candidate for further studies in medicine, pharmacology, and biology.