CP/MAS spectroscopy in the determination of the tautomeric forms of gossypol, its Schiff bases and hydrazones in the solid state.
New Schiff bases and new hydrazones were synthesized and studied by (13)C and (15)N CP/MAS spectroscopy and by (1)H--(1)H COSY, (1)H--(13)C HMBC, (1)H--(13)C HSQC, (1)H--(15)N HMQC and (1)H--(15)N HSQC correlations. The CP/MAS investigation of gossypol has demonstrated that in the solid state it exists exclusively in the aldehyde-aldehyde tautomeric form. In contrast, CP/MAS studies of hydrazones and Schiff bases reveal that these compounds occur in the solid state in the N-imine-N-imine and enamine-enamine tautomeric forms, respectively. It is shown that the (13)C resonances of C-6, C-7 and C-11 carbon atoms are suitable for distinguishing between the tautomeric forms of aza-derivatives of gossypol in the solid state. Furthermore, we have proved that the (15)N CP/MAS spectra can be used to identify these tautomeric forms.
Przybylski
Piotr
P
Faculty of Chemistry, A. Mickiewicz University, Grunwaldzka 6, 60-780 Poznan, Poland. piotrp@amu.edu.pl
Schilf
Wojciech
W
Kamienski
Bohdan
B
Brzezinski
Bogumil
B
Bartl
Franz
F
D002247:Carbon Isotopes / Q000737:chemistry; D006072:Gossypol / Q000737:chemistry*; D006835:Hydrazones / Q000737:chemistry*; D007536:Isomerism; D008968:Molecular Conformation; D009587:Nitrogen Isotopes / Q000737:chemistry; D044367:Phase Transition; D011208:Powders; D012545:Schiff Bases / Q000737:chemistry*
D002247:Carbon Isotopes; D006835:Hydrazones; D009587:Nitrogen Isotopes; D011208:Powders; D012545:Schiff Bases; D006072:Gossypol