A rigid metallohexameric macrocycle composed of endo- and exo-cyclic bisterpyridine-metal complexes

Abstract

Synthesis of terpyridine-based building blocks has allowed the self-assembly of a nanosized metallomacrocycle with precisely positioned, peripheral metal complexes. Construction of the precursors included the assembly of a heteroleptic bisterpyridine-Ru(II) complex possessing a diiodoaryl moiety that was subsequently reacted with two equivalents of 4′-ethynyl-2,2′ : 6′,2′′-terpyridine via a Pd(0)-catalyzed Sonagashira coupling, to generate the requisite monomer with two, 120°-juxtaposed metal coordination sites. Addition of one equivalent of Fe(II) to one equivalent of the bisligand afforded the metallocycle with 12 metals [6 internal Fe(II) ions and 6 external Ru(II) ions] measuring ca. 7 nm in diameter.