First example of a pyrylium salt dimerisation in solution

Abstract

A pyrylium salt is capable of forming dimers in non-polar solvents at room temperature. The dimer, corresponding to a head-to-tail configuration in which the monomer dipole moments are parallel, has been characterized by its electronic absorption spectra, fluorescence spectra and its fluorescence lifetime. The dimer–monomer equilibrium constant is found to be 2.7 × 10⁵ dm³ mol^–1.