title: CP/MAS spectroscopy in the determination of the tautomeric forms of gossypol, its Schiff bases and hydrazones in the solid state.
abstract: 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.
authors.affiliation: Faculty of Chemistry, A. Mickiewicz University, Grunwaldzka 6, 60-780 Poznan, Poland. piotrp@amu.edu.pl
authors.forename: Piotr
authors.initials: P
authors.lastname: Przybylski
authors.forename: Wojciech
authors.initials: W
authors.lastname: Schilf
authors.forename: Bohdan
authors.initials: B
authors.lastname: Kamienski
authors.forename: Bogumil
authors.initials: B
authors.lastname: Brzezinski
authors.forename: Franz
authors.initials: F
authors.lastname: Bartl
mesh_terms: 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*
chemical_list: D002247:Carbon Isotopes; D006835:Hydrazones; D009587:Nitrogen Isotopes; D011208:Powders; D012545:Schiff Bases; D006072:Gossypol