In this work, the influence of supramolecular effects on the reactivity and the geometry of radical ions is illustrated by two examples. (1) The reactivity of the radical anions of aromatic carbaldehydes towards the formation of semidiones depends on two main factors: the spin population at the carbonyl carbon atom and the strength of the anion-cation interaction (ion-pairing conditions). In the presence of the starting aldehyde and of the ketyl, the diolate formed by a primary ketyl-ketyl coupling undergoes an electron transfer and two hydrogen transfer to yield the semidione. (2) The study of the radical anions and cations of crownophanes has revealed that the radical anions are not bound to the counterions (Li+, Na+, K+, Cs+) preferentially at the crown-ether moiety, but that an association with the delocalised, negatively charged pi system of the tetraphenylethene moiety is induced. On the contrary, there are indications that a positively charged tetraphenylethene moiety allows the interaction of a cation with the crown-ether
