SPECTROSCOPIC STUDY OF GOSSYPOL-LANTHANIDE CATION COMPLEXES IN ACETONITRILE SOLUTION

The formation of 1:1 complexes of gossypol with lanthanide(III) cation s (M = Dy, Gd, Tb and Eu) was studied by FT-IR-and UV-visible spectros copy. The FT-IR spectra evidenced the aldehyde-aldehyde tautomer chang e to the lactol-lactol tautomer of gossypol upon the complexation. Thi s result was also confirmed by UV visible absorption spectra measureme nts. On the basis of the Hildebrant Benessi equation, the formation co nstants K for gossypol-lanthanide(III) cations complexes in acetonitri le were determined to be in the range of 3.5 x 10(4) mol dm(-3). (C) 1 997 Elsevier Science B.V.