Synthesis, FT-IR, 1H, 13C NMR, ESI MS and PM5 studies of a new Mannich base of polyether antibiotic – Lasalocid acid and its complexes with Li+, Na+ and K+ cations

The polyether antibiotic Lasalocid acid has been converted to its Mannich base derivative by a chemoselective one-pot reaction with formaldehyde and morpholine through the decarboxylation process. Spectroscopic studies of the structure of this new derivative have shown that in this ortho-phenol Mannich base the OH⋯N intarmolecular hydrogen bond is present. The compound forms complexes with Li+, Na+ and K+ cations of exclusively 1:1 stoichiometry. The structures of these complexes have been studied and visualized by semi-empirical calculation based on results of spectrometric and spectroscopic investigation. It is demonstrated that in contrast to Lasalocid acid the novel Mannich type derivative forms preferential complexes with Li+ cation.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A new ortho-phenol Mannich base of Lasalocid was synthesized by chemoselective one-pot reaction. ► The compound obtained is a useful ligand for complexation of monovalent cations. ► Spectroscopic characterization of the ligand and prepared complexes is given. ► Semiempirical calculations of structures of the complexes studied are presented.