title: Conformational analysis of quinine and its pseudo enantiomer quinidine: a combined jet-cooled spectroscopy and vibrational circular dichroism study.
abstract: Laser-desorbed quinine and quinidine have been studied in the gas phase by combining supersonic expansion with laser spectroscopy, namely, laser-induced fluorescence (LIF), resonance-enhanced multiphoton ionization (REMPI), and IR-UV double resonance experiments. Density funtional theory (DFT) calculations have been done in conjunction with the experimental work. The first electronic transition of quinine and quinidine is of π-π* nature, and the studied molecules weakly fluoresce in the gas phase, in contrast to what was observed in solution (Qin, W. W.; et al. J. Phys. Chem. C2009, 113, 11790). The two pseudo enantiomers quinine and quinidine show limited differences in the gas phase; their main conformation is of open type as it is in solution. However, vibrational circular dichroism (VCD) experiments in solution show that additional conformers exist in condensed phase for quinidine, which are not observed for quinine. This difference in behavior between the two pseudo enantiomers is discussed.
authors: CNRS, Institut des Sciences Moléculaires d'Orsay (ISMO), UMR8214, Orsay, France.
authors: Ananya
authors: A
authors: Sen
authors: Aude
authors: A
authors: Bouchet
authors: Valeria
authors: V
authors: Lepère
authors: Katia
authors: K
authors: Le Barbu-Debus
authors: D
authors: D
authors: Scuderi
authors: F
authors: F
authors: Piuzzi
authors: A
authors: A
authors: Zehnacker-Rentien
mesh_terms: D002929:Cinchona / Q000737:chemistry*; D002942:Circular Dichroism; D004583:Electrons; D005740:Gases; D007834:Lasers; D008958:Models, Molecular; D008968:Molecular Conformation; D011789:Quantum Theory; D011802:Quinidine / Q000737:chemistry*; D011803:Quinine / Q000737:chemistry*; D013057:Spectrum Analysis; D013237:Stereoisomerism; D013816:Thermodynamics
chemical_list: D005740:Gases; D011803:Quinine; D011802:Quinidine