X-ray, FT-IR, ESI MS and PM5 studies of Schiff base of gossypol with allylamine and its complexes with alkali metal cations and perchlorate anion

Abstract

Crystals of the Schiff base derivative of gossypol with allylamine (GSBAL) were grown and subsequently examined by X-ray diffraction and FT-IR methods. The crystal space group is C2/c with a = 16.057(1) Å , b = 14.112(1) Å , c = 27.185(2) Å , b = 99.371(5) and Z = 8. In the crystal, GSBAL exists in the enamineenamine tautomeric form. The FT-IR spectral features of the crystals are in agreement with the X-ray data indicating that both parts of the molecule are similarly intramolecular hydrogen-bonded but different intermolecular hydrogenbonded, although the molecule is symmetrically substituted. On the basis of the electrospray ionization mass spectrometry (ESI MS) experiments, it has been shown for the first time that Schiff base of gossypol forms complexes with the perchlorate anion and metal cations simultaneously. The ESI MS spectra of the 1:1:1 mixtures of GSBAL:GOS:M ? , in the positive and negative ion detection mode, have indicated the preferential formation of the 1:1 complexes of GSBAL with M ? (Li, Na or K) and ClO 4 -over the respective complexes forming between GOS and the metal cation or the anion. The PM5 semiempirical calculations have allowed visualization of the most energetically favourable structures of these two types of GSBAL complexes.

Synthesis, crystal structures and antibacterial activity studies of aza-derivatives of phytoalexin from cotton plant – gossypol

“…Schiff bases of gossypol 1-6, 8, 10, 11, 13, 14, 16-18 were synthesized following our procedures given in Refs. [31][32][33][34][35]38,43,67,68], whereas hydrazones of gossypol 19-24, 26, 27 -following our procedures given in Refs. [19,38,69,70].…”

“…Earlier studies have shown that the activity of gossypol is rather bacteriostatic than antibacterial [26][27][28] although gossypol structural analogues like hemigossypol, 2,7-dihydroxycadalene, lacinilene and their respective 7-methyl esters have shown very promising antibacterial activity [29,30]. The limited antibacterial activity of gossypol can be probably concerned with the relatively poor ability to form complexes with the monovalent cations such as Na þ or K þ [31]. In our earlier papers we have reported the synthesis and the physicochemical properties of some Schiff bases or hydrazones of gossypol [14,19,32,33].…”

“…The aza-derivatives of gossypol in the solution can be present in the various tautomeric forms (Scheme 1) which differ from each other by the number of phenolic groups [33,37,38]. Taking into account the enormous number of Schiff bases of gossypol synthesized, only several of them have been studied by the X-ray methods [31,[39][40][41][42][43]. No crystal structures of any gossypol hydrazones have been reported till now despite the fact that many crystal structures of other groups of hydrazones, e.g.…”

Interplay of thermochemistry and Structural Chemistry, the journal (volume 19, 2008) and the discipline

“…This has led to the synthesis of azaderivatives of gossypol in an attempt to decrease its toxicity [316]. Therefore, in the subsequent paper, Przybylski et al [317] discussed the growth of crystals of the Schiff base derivative of gossypol with allylamine (GSBAL) and the investigation of these crystals using X-ray diffraction and FTIR. The authors determined that as a crystal GSBAL is in its enamine-enamine tautomeric form.…”

Complexes of heterocyclic aza‐derivatives of phytoalexin from cotton plant‐gossypol with alkali metal cations and perchlorate anion studied by ESI mass spectrometric method in the positive and negative modes

“…[13] Relatively low antibacterial activity of gossypol is probably related to its limited ability to form complexes with monovalent cations such as Na + or K + . [14] Our earlier papers have reported the synthesis and the physicochemical properties of Schiff bases or hydrazones of gossypol [15,16] as well as their EI-MS and ESI-MS fragmentation pathway investigations. [17] Furthermore, it has been demonstrated that gossypol Schiff bases occur in the enamine-enamine tautomeric forms, whereas gossypol hydrazones in the N-imine-N-imine ones.…”