Herein, we demonstrate that the dimerization behavior of amine-substituted dicyanomethyl radicals can be switched from σ- to π-dimerization simply by varying the electron-donating substituents. For dicyanomethyl radicals with a 4,4'-ditolylamine (DT ) or a phenothiazine (PT ) substituent, the monomeric radical form and the corresponding dimer connected by a reversible C-C bond (σ-dimer) are in equilibrium in solution. On the other hand, the radical with the julolidine skeleton (JD ) does not undergo σ-dimerization and was isolated as a stable radical in spite of the absence of bulky protecting groups. X-ray single-crystal analysis revealed that JD forms the π-dimer in the crystalline state, and variable-temperature spectroscopy showed that JD is in equilibrium with the π-dimer in toluene solution. DFT calculations point to the importance of electrostatic interactions as a driving force for the π-dimerization of JD because of its polarized structure.

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Good results can be expected from placement of Gianturco stents except when CT shows the obstruction to be totally enveloped by tumor.

Electron-rich cycloparaphenyleneacetylenes as well as their twin "glasses-like" conjugates form stable complexes with fullerenes.

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