Structural Studies and Spectroscopic properties of Quinolizidine Alkaloids (+) and (-)-Lupinine in different media

JOSE RUIZ HIDALGO; MAXIMILIANO ALBERTO. IRAMAIN; SILVIA ANTONIA. BRANDÁN

Journal of Materials and Environmental Sciences

JMESCN

Año: 2019 vol. 10 p. 854 - 871

2028-2508

The quinolizidine alkaloids, as numerous species of lupine (Lupinus spp.), are toxic and have biological effect on the nervous system. Hence, four (+) and (-)- molecular structures of quinolizidine alkaloid lupinine, named C0, C1a, C1b and C1c have been theoretically determined in gas phase and in aqueous solution by using hybrid B3LYP/6-31G* calculations. The studied properties have evidenced that the most stable C1c form present the higher populations in both media while the predicted infrared, Raman, 1H-NMR and 13C-NMR and ultra-visible spectra suggest that probably other forms in lower proportion could be also present in water, chloroform and benzene solutions, as evidenced by the low RMSD values observed in the 1H- and 13C-NMR chemical shifts. The C1c form presents the lower corrected solvation energy in water while the NBO and AIM studies suggest for this form a high stability in both media. In addition, the predicted ECD spectra of all (+) and (-)-lupinine forms in methanol solution evidence clearly that the C1b forms is present in the solution because its spectrum presents a negative Cotton effect as observed in the experimental one.