Self-Assembled Bis-Acridinium Tweezer Equilibria Controlled by Multi-Responsive Properties

Protonated and methylated bis-acridinium tweezers built around a 2,6-diphenylpyridyl and an electron enriched 2,6-di(p-anisyl)pyridyl spacer have been synthesized. These tweezers can self-assemble in their corresponding homodimers and the associated thermodynamic parameters have been probed in organic solvents. The switching properties of the tweezers have been exploited in biphasic transfer experiments showing the shift of the equilibria towards the homodimers. Moreover, the thermodynamic parameters of the formation of the reduced methylated homodimers investigated by electrochemical experiments revealed the dissociation of the dimers. Thus, in addition to solvent and temperature, the pH and redox responsiveness of the acridinium units of the tweezers make it possible to modulate to a larger extent the monomer-dimer equilibria.