An experimental and theoretical study on the molecular interactions of N-aromatic L-proline in the condensed phase

Abstract

Intermolecular interactions, such as halogen bonding, π-π stacking, F…π interactions, and anion-π interactions, play pivotal roles in the fields of chemistry, materials science, and biological technology. In this study, N-aromatic L-proline and its fluorinated derivatives were chosen as exemplars. X-ray diffraction and NMR techniques were employed to investigate these interactions in both solid-state and solution phases respectively. Theoretical investigations encompassing geometry optimization along with QTAIM (Quantum Theory of Atoms in Molecule) and IGMH (Independent Gradient Model based on the Hirshfeld partition) analyses provided profound insights into the intermolecular interactions. Parameters obtained from X-ray diffraction analysis of single crystals provide compelling evidence for F…F interaction with intermolecular F…F distances measuring 2.879 Å and 3.125 Å in compounds 2 and 3 crystal structures respectively. QTAIM and IGMH analyses indicate that F…π contacts significantly contribute to the formation of these two fluorinated crystals while H-bonding and CH…π contacts predominantly shape the crystal structure of the non-fluorinated L-proline derivative.