Formation of a Macrocycles-in-a-Macrocycle Superstructure with All-gauche Conformation by Reversible Radical Association

Abstract

The formation of an unprecedented macrocycles-in-a-macrocycle (MIM) superstructure by reversible radical-radical association of a triphenylamine based monomer terminated with three dicyanomethyl radicals is presented. The reaction yield is nearly quantitative and the obtained macrocycle contains three small dimeric macrocycles according to X-ray crystallographic analysis. The six monomer molecules are linked by nine long dynamic covalent C(sp³ )-C(sp³ ) bonds that all adopt a gauche conformation. Such a conformation favors the formation of a MIM structure rather than a 2D network with an all-anti conformation. Two enantiomers with left-/ right-handed chirality exist in the single crystals of the superstructure.

Keywords: covalent assembly; dynamic covalent bonds; gauche conformation; macrocycles; radical-radical association.