Chalcogen analogues of nicotine lactam studied by NMR, FTIR, DFT and X-ray methods

• Chalcogen analogues of nicotine lactam have been studied.
• Delocalized structure of oxo and thionicotine becomes weaker in the resonance structure of selenonicotine.
• Unlike the nicotine and its derivatives, the chalcogen lactams of nicotine are prone to π⋯π stacking.

The selenoanalogue of nicotine has been synthesized and characterized by spectroscopic and X-ray diffraction methods. The crystals of selenonicotine are isomorphic with the thionicotine homologue and consist of molecules engaged in columnar π⋯π stacking interactions between antiparallely arranged pyridine moieties. These interactions, absent in other crystals containing nicotine fragments, seem to be induced by the presence of a lactam group. The molecular structures in the vacuum of the oxo-, thio- and selenonicotine homologues have been calculated by the DFT method and compared with the available X-ray data. The delocalized structure of thionicotine is stabilized by intramolecular CH⋯S hydrogen bond, which becomes weaker in the partial zwitterionic resonance structure of selenonicotine in favor of multiple CH⋯Se intermolecular hydrogen-bonds. The calculated data allow a complete assignment of vibration modes in the solid state FTIR spectra. The 1H and 13C NMR chemical shifts were calculated by the GIAO method with B3LYP/6-311G(3df) level. A comparison between experimental and calculated theoretical results indicates that the density functional B3LYP method provided satisfactory results for predicting FTIR, 1H, 13C NMR spectra properties.

The article provides characteristics of the most widely used biomarker of nicotine intake – cotinine and its congeners.Figure optionsDownload as PowerPoint slide