title: Pseudo-cyclic face-to-face rigid structure caused by the intramolecular ion pair effect.
abstract: Six 3-methylpyridine zwitterions and six quinoline zwitterions were synthesized through the reaction of 4-hydroxycoumarins, p-benzoquinone and the corresponding N-aromatics. The novel pseudo-cyclic face-to-face rigid structure of the zwitterion was elucidated by (1)H-NMR at different temperatures, and assumed to be caused by both the intramolecular ion pair attraction and the steric interaction.
authors.affiliation: Department of Chemistry, Shaoguan University, Shaoguan 512005, PR China. zhisland@yahoo.com.cn
authors.forename: Sheng-Ling
authors.initials: SL
authors.lastname: Zhang
authors.forename: Zhi-Shu
authors.initials: ZS
authors.lastname: Huang
authors.forename: Lian-Quan
authors.initials: LQ
authors.lastname: Gu
mesh_terms: D015110:4-Hydroxycoumarins / Q000138:chemical synthesis / Q000737:chemistry; D007477:Ions; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D011725:Pyridines / Q000737:chemistry; D011804:Quinolines / Q000737:chemistry
chemical_list: D015110:4-Hydroxycoumarins; D007477:Ions; D011725:Pyridines; D011804:Quinolines