Triarylpyrylium salts: dynamics of the monomer–dimer equilibrium via a triplet absorption study

Dimers formed by triarylpyrylium tetrafluoroborates in toluene and polystyrene were studied at room temperature by nanosecond flash photolysis. The time evolution of the differential absorption spectra observed for toluene solutions was interpreted in terms of a monomer–dimer equilibrium in the ground state; the association (∼109 l mol−1 s−1) and dissociation (∼104 s−1) rate constants were derived from the concentration dependence of the transient signals.