Ternary π–π Stacking Complexes by Allosteric Regulation in Multilayer Nanographenes

Construction of π-π stacking supramolecular complexes with more than two different components is challenging due to the weak and directionless nature of dispersion interactions. Here, we report ternary complexes of a ditopic nanographene tetraimide (<b>1</b>), α-substituted phthalocyanine (<b>Pc</b>), and polyaromatic hydrocarbons (PAHs) in solution and the crystalline state via allosteric regulation. Binding of one <b>Pc</b> gives rise to significant distortion and conformational changes in <b>1</b> that in turn lead to the inhibition of the second binding of <b>Pc</b>. The conformational changes associated with first binding allowed an allosteric binding of a third component (PAHs) to form ternary complexes in solution. ¹H NMR titration revealed moderately high thermodynamic stability for the ternary complexes in CDCl₃. Competition between allosterically regulated ternary complexes ([<b>Pc</b>·<b>1</b>·PAH]) and 1:2 stoichiometric binary complexes of <b>1</b> with PAHs ([PAH·<b>1</b>·PAH]) was elucidated. Further, the selective formation of ternary complexes in solution led to the generation of ternary cocrystals from a 1:1:1 mixture of three components in solution. Our work shows that large π-conjugated nanographenes designed with allosteric recognition sites allow the construction of multilayer ternary complexes in solution and the solid state even with dispersive π-π interactions.