title: Monensin A methyl ester complexes with Li+, Na+, and K+ cations studied by ESI-MS, 1H- and 13C-NMR, FTIR, as well as PM5 semiempirical method.
abstract: Monensin A methyl ester (MON1) was synthesized by a new method and its ability to form complexes with Li+, Na+, and K+ cations was studied by electrospray ionization-mass spectroscopy (ESI-MS), 1H and 13C nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), and PM5 semiempirical methods. It is shown that MON1 with monovalent metal cations forms stable complexes of 1:1 stoichiometry. The structures of the complexes are stabilized by intramolecular hydrogen bonds in which the OH groups are always involved. In the structure of MON1, the oxygen atom of the C=O ester group is involved in very weak bifurcated intramolecular hydrogen bonds with two hydroxyl groups, whereas in the complexes of MON1 with monovalent metal cations the C=O ester group is not engaged in any intramolecular hydrogen bonds. Furthermore, it is demonstrated that the strongest intramolecular hydrogen bonds are formed within the MON1-Li+ complex structure. The structures of the MON1 and its complexes with Li+, Na+, and K+ cations are visualized and discussed in detail.
authors.affiliation: Faculty of Chemistry, A. Mickiewicz University, Grunwaldzka 6, 60-780 Poznan, Poland.
authors.forename: Adam
authors.initials: A
authors.lastname: Huczyński
authors.forename: Piotr
authors.initials: P
authors.lastname: Przybylski
authors.forename: Bogumil
authors.initials: B
authors.lastname: Brzezinski
authors.forename: Franz
authors.initials: F
authors.lastname: Bartl
mesh_terms: D000465:Algorithms; D002412:Cations / Q000737:chemistry*; D006860:Hydrogen Bonding; D008094:Lithium / Q000737:chemistry; D008672:Metals, Alkali / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D011188:Potassium / Q000737:chemistry; D012964:Sodium / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D017550:Spectroscopy, Fourier Transform Infrared; D013388:Succinimides / Q000138:chemical synthesis* / Q000737:chemistry*
chemical_list: D002412:Cations; D008672:Metals, Alkali; C510619:Pacific Blue succinimidyl ester; D013388:Succinimides; D008094:Lithium; D012964:Sodium; D011188:Potassium