Abstract
A new Schiff base of gossypol with 2-(aminomethyl)-18-crown-6 (GSCC) was shown to be capable of complexation of monovalent cations. This process of complex formation was studied by ESI mass spectrometry, 1H NMR and FT-IR spectroscopy as well as by PM5 semiempirical method. It was found that this Schiff base can form 1:2 complexes with all monovalent and 1:4 complexes only with Li + and Na + cations. The Schiff base in the complex with protons, localised on the N atoms, exists in the imine–imine tautomeric form. GSCC in all other complexes with the metal cations occurs only in the enamine–enamine tautomeric form. In the 1:2 complexes of GSCC with Li +, Na + and K + cations, they are coordinated only by the oxygen atoms of the crowns, whereas in the complexes with Rb + or Cs + cations they are coordinated by the oxygen atoms of the crowns as well as O 1–H and O 1′–H groups. In the complexes of the 1:4 stoichiometry, the Li + and Na + cations are coordinated by the oxygen atoms of the crowns as well as of the N atoms of the Schiff base. The structures of the complexes are calculated by PM5 semiempirical method and discussed.
Published Version
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