Barnes JC1, Frasconi M, Young RM, Khdary NH, Liu WG, Dyar SM, McGonigal PR, Gibbs-Hall IC, Diercks CS, Sarjeant AA, Stern CL, Goddard WA 3rd, Wasielewski MR, Stoddart JF.
J Am Chem Soc. 2014 Jul 30;136(30):10569-72. doi: 10.1021/ja505093d. Epub 2014 Jul 21.An octacationic homocatenane comprised of two mechanically interlocked cyclobis(paraquat-p-phenylene) rings has been obtained from the oxidation of the septacationic monoradical with nitrosonium hexafluoroantimonate. The nanoconfinement of normally repulsive bipyridinium units results in the enforced π-overlap of eight positively charged pyridinium rings in a volume of <1.25 nm(3). In the solid state, the torsional angles around the C-C bonds between the four pairs of pyridinium rings range between 16 and 30°, while the π-π stacking distances between the bipyridinium units are extended for the inside pair and contracted for the pairs on the outside--a consequence of Coulombic repulsion between the inner bipyridinium subunits. Read More