Conformational properties of chiral tobacco alkaloids by DFT calculations and vibrational circular dichroism: (−)-S-anabasine

摘要: Abstract A thorough DFT and MM study of the conformational landscape, molecular electronic structures (−)-S-anabasine is reported aimed to reveal mechanism controlling its preference. Although flexibility diversity this system quite extensive, only two are populated both in gas-phase solution (CCl4 DMSO). NBO-aided structure analyses performed for eight conformers representing minima potential energy surface indicate that steric electrostatic factors determinant distribution sample gas phase. Nonetheless, hyperconjugative effects key force tipping balance equilibrium between main rotamers. Increasing polarity medium (using IEF-PCM formalism) barely affect profile, although a slight increase theoretical population those more affected by interactions predicted. The validity models calculated populations endorsed accurate reproduction IR VCD spectra (recorded pure liquid CCl4 solution) (that have been firstly recorded assigned present work) which consistent with occurrence 2:1 ratio.