Département de chimie moléculaire

We have established that bipyridinium radicals can be reversibly $π$-dimerized under the combined effects of chem. (proton transfer) and electrochem. (electron transfer) stimuli. Our investigations also led to the discovery that a bis-pyridinyl appended calixarene intermediate is involved in a fully reversible redox-triggered $\sigma$-dimerization process. The structure of the most stable intramol. $\sigma$-dimer was provided by computational chem. and its complete conversion into a noncovalent $π$-dimer could be triggered chem. by addn. of protons, leading to the formation of protonated cation radicals. Theor. data collected with the N-methylated and N-protonated $π$-dimers also support the existence of multivariant orientations in $π$-bonded dimers of viologen cation-radicals. [on SciFinder(R)]