Nature of anion-templated π+–π+ interactions

Abstract

Interaction between positively charged aromatic groups (π⁺–π⁺) is characterized by anti-parallel, displaced-stacked structures in the presence of counteranions. Binding energies of pyridinium, N-methylpyridinium and N-methylimidazolium dimers are much larger than that of benzene–pyridine (π–π) and pyridinium–benzene (π⁺–π). Stabilization is attributed to attractive electrostatic interaction with significant dispersion contribution.