A Molecular Seesaw Balance: Evaluation of Solvent and Counteranion Effects on Pyridinium−π Interactions

A molecular seesaw balance 1·MeI has been developed
to measure pyridinium−π interactions. This balance adopts
two distinct conformers, A and B, which
are stabilized by a cation−π interaction and a π–π
interaction, respectively. The conformer ratio was determined on the
basis of the averaged 3J coupling constants
for H1–C–C–H2 and the corresponding boundary J values for conformers A and B. The effects of the solvent and the counteranion on the ΔG values were investigated using this molecular balance.
Thermodynamic parameters obtained from a van’t Hoff plot helped
us to better understand the solvent and counteranion effects.

一种分子天平平衡1·MeI已被开发，用以测量吡啶阳离子-π相互作用。该平衡采用两种独特的构象，A和B，分别通过阳离子-π相互作用和π-π相互作用得到稳定。构象比率的确定基于H1-C-C-H2的平均3J耦合常数以及构象A和B相应的边界J值。利用该分子平衡研究了溶剂和反离子对ΔG值的影响。从van’t Hoff图中获得的动力学参数有助于我们更好地理解溶剂和反离子的效应。