Electrochemically Induced Intermolecular Anion Transfer

Two macrocyclic anion receptors with the proper signaling units were designed to control intermolecular anion transfer using an electrochemical stimulus. The solubility of both receptors drastically improved when one equivalent of benzoate was added to the suspension in the NMR tube. Macrocycles 1 and 2 were prepared via multistep synthetic pathways. An important enhancement of the MLCT emission intensity was initially seen when benzoate was added to a solution of macrocycles 1. Spectroelectrochemical experiments were conducted for a mixture which contained receptors 1,2 and benzoate in equimolar concentration in acetone. The reversibility of the anion transfer could be shown and hence, electrochemical reduction of ferrocenium to ferrocene at -0.2 V was simultaneously accompanied by an enhancement of the emission intensity.