Discrete Quadruple Stacks Formed in a Nanosized Metallorectangle

An iridium-cornered nanosized metallorectangle was obtained by combining a quinoxalinophenanthrophenazine-connected Janus-di-imidazolylidene ligand and 4,4'-bipyridine. This metallorectangle was used as host for a series of planar molecules, including pyrene, triphenylene, perylene, coronene, and N,N'-dimethyl-naphthalenetetracarboxy-diimide (NTCDI). The binding of coronene and NTCDI followed a strongly positive cooperative 1:2 stoichiometric binding model, as the inclusion of the first guest generates the geometrical requirements for the optimum encapsulation of the second planar molecule. The simultaneous encapsulation of coronene and NTCDI produces a heteroguest inclusion system, whose exchange dynamics was studied by means of variable temperature ¹H NMR spectroscopy.