Schiff base of gossypol with 3,6,9‐trioxa‐decylamine complexes with monovalent cations studied by mass spectrometry, ¹H‐NMR, FTIR, and PM5 semiempirical methods

Abstract

A new Schiff base of gossypol with 3,6,9-trioxo-decylamine (GSTB) forms stable complexes with monovalent cations. This process of complex formation was studied by electrospray ionization mass spectrometry, (1)H-NMR and FTIR spectroscopy, and the PM5 (parametric method 5) semiempirical method. It is found that GSTB forms 1 : 1 and 1 : 2 complexes with Li(+) and Na(+) and 1 : 1 complexes with K(+), Rb(+), or Cs(+) cations and exists in all these complexes in the enamine-enamine tautomeric form. Moreover, within these complexes only Li(+) cations can fluctuate between the oxygen atoms of trioxo-alkyl chains. All other cations are strongly localized. In the complex of GSTB with two protons localized on the N atoms of the Schiff base, the imine-imine tautomeric form is realized. The complexes of the Schiff base with K(+), Rb(+), or Cs(+) cations are the 1 : 1 type with the oxygen atoms of the trioxo-alkyl chains, as well as the O(1)H or O(1')H group coordinating the cation. The structures of the complexes are calculated by the PM5 semiempirical method and discussed.

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

“…Recently, we have synthesized a new Schiff base of gossypol with 3,6,9-trioxa-decylamine, capable of complexing some monovalent cations. 60 In all these complexes the enamine-enamine tautomeric forms were detected. Only for protonated Schiff base of gossypol with 3,6,9-trioxa-decylamine was the imine-imine tautomeric form realized.…”

Multinuclear magnetic resonance, electrospray ionization–mass spectroscopy, and parametric method 5 studies of a new derivative of gossypol with 2‐thiophenecarbohydrazide as well as its complexes with LI+, Na+, K+, RB+, and Cs+ cations

“…The coordinating distances and the number of coordinating oxygen atoms suggest that all the cations studied can undergo fast fluctuations within the structures of the complexes, as demonstrated for the complexes of crown ethers or derivatives of gossypol containing oxaalkyl chains with monovalent cations. 57,47,50 The calculated partial charges of the cation complexes indicate an involvement of the cations in the coordination process. Their values decrease in the sequence Li + > Na + & K + > Rb + & Cs + , which is in a full agreement with that obtained from the DHOF values as well as the ESI MS studies.…”

“…39,40 Recently studied derivatives of gossypol are able to complex monovalent and divalent metal cations. [41][42][43][44][45][46][47][48][49][50] The new derivative of gossypol comprises two additional carbonyl groups and two thiophene rings, which can improve the complexation ability of this compound. In the present article we report the electrospray ionization-mass spectroscopy (ESI-MS), spectroscopic, and Parametric Method 5 (PM5) studies of a new derivative of gossypol with 2-thiophenecarbohydrazide (GHHT) as well as its complexes with Li + , Na + , K + , Rb + , and Cs + cations.…”

Biological Properties of Schiff Bases and Azo Derivatives of Phenols

“…This group of gossypol derivatives can, similar to gossypol, occur in different tautomeric forms (Scheme 6). Gossypol Schiff bases and its complexes with monovalent as well as divalent metal cations exist in the enamine-enamine tautomeric form [60, 67, 69, 75, 76, 78-81, 89, 90, 104, 105, 107, 108, 120-122] [123][124][125][126][127][128][129][130][131][132], whereas the imine-imine tautomer was only obserevd for protonated Schiff bases of gossypol [123,125,128,129,131,132].…”