January 25, 2023
Journal Article

Gas phase protonated nicotine is a mixture of pyridine- and pyrrolidine- protonated conformers: implications for its native structure in the acetylcholine receptor

Abstract

The infrared spectra of the gas phase protonated nicotine has been measured in the never probed N-H “fingerprint region” (3,200–3,500 cm-1). With the aid of high-level electronic structure calculations, it is unequivocally determined that gas phase nicotine is a 2:1 mixture of both pyridine and pyrrolidine protomers, in sharp contrast to the previous spectroscopic study suggesting a single population of the pyridine protomer. Our study further establishes the small energy difference between the pyridine and pyrrolidine protomers. One of the gas phase nicotine pyrrolidine protomers has the closest conformational resemblance among all low-lying energy isomers with the X-ray structure of nicotine in the nicotinic acetylcholine receptor (nAChR).

Published: January 25, 2023

Citation

Takeda N., K. Hirata, K. Tsuruta, G.D. Santis, S.S. Xantheas, S. Ishiuchi, and M. Fujii. 2022. Gas phase protonated nicotine is a mixture of pyridine- and pyrrolidine- protonated conformers: implications for its native structure in the acetylcholine receptor. Physical Chemistry Chemical Physics 10, no. 24:5786-5793. PNNL-SA-163173. doi:10.1039/D1CP05175J