Spectroscopic and semiempirical studies of gossypol complexes with Fe2+ and Fe3+ cations

The schiff base of gossypol with 3,6,9,12,15,18,21,24‐octaoxa‐pentacosylamine complexes and monovalent cations studied by electrospray ionization–mass spectrometry, 1H nuclear magnetic resonance, Fourier transform infrared, as well as PM5 semiempirical methods

“…This conclusion is in a good agreement with the results of our previous studies of gossypol complexes with some cations in which the ketol-ketol form of gossypol was observed and with our earlier studies of some other gossypol Schiff bases. 57,59 A comparison of the spectra of 1:6 complexes of GSOB with Li ϩ and Na ϩ (Figures 1b and c) with the respective spectrum of GSOB indicates also strong changes in the region of (OH) vibrations but different than those in the spectra of protonated species. In the FTIR spectra of both complexes the (OH) vibrations assigned to the O 1 H and O 1Ј H hydroxyl groups shift from 3482 cm Ϫ1 toward 3335 cm Ϫ1 and overlap the stretching vibrations of the O 6 H and O 6Ј H hydroxyl groups, which remain in the unchanged position.…”

Biological Properties of Schiff Bases and Azo Derivatives of Phenols

“…For the complexes with Be 2+ , Ni 2+ , Cu 2+ , Dy 3+ , Gd 3+ , Tb 3+ and Eu 3+ [32,[54][55][56] cations in acetonitrile the lactol-lactol tautomeric form is realized whereas for complexes with Zn 2+ , Fe 2+ and Fe 3+ cations, the ketol-ketol form of gossypol is observed [32,56,57]. The exemplary structures of complexes with metal cations coordinated by different tautomeric forms of gossypol are shown in Scheme 4 and Scheme 5 [32,57].…”

Structures of Complexes of Gossypol with Ferrous Sulfate Based on High‐Performance Liquid Chromatography Separation, Spectroscopic Analysis, and PM3 calculations

“…Muzaffaruddin and Saxena showed that a 1:1 molar ratio of ferric iron to gossypol formed an iron–gossypol complex, in which the two perihydroxyl groups in gossypol were the most plausible sites for the ferric irons to be chelated . The most stable structures of complexes formed by gossypol and iron salts in acetonitrile solution at various molar ratios were discussed based on UV‐Vis and FT‐IR spectroscopy analysis . These studies have successfully explicated the structure of iron–gossypol complex formed at a 1:1 molar ratio.…”