The structures of monensin A derivatives and its complexes with some monovalent cations studied by the AM1d, PM3 as well as PM5 semiempirical methods

The structures and the crystallographic data for monensin and its complexes with Na+, K+ and Ag+ cations have been compared with the parameters calculated by the PM5, PM3 and AM1d semiempirical methods. It is demonstrated that the PM5 calculations are effective for the visualisation of the probable structures of supramolecular species and generate very reliable structural parameters. Only for the complexes of monensin with silver cations the AM1d semiempirical method seems to be more effective than the PM5 and PM3 methods. The most energetically probable structures of monensin hydrates as well as monensin complexes with Na+, K+ and Ag+ cations are visualised.