Ternary π–π\nStacking Complexes\nby Allosteric Regulation in Multilayer Nanographenes

Construction of π–π stacking supramolecular\ncomplexes with more than two different components is challenging due\nto the weak and directionless nature of dispersion interactions. Here,\nwe report ternary complexes of a ditopic nanographene tetraimide (<b>1</b>), α-substituted phthalocyanine (<b>Pc</b>),\nand polyaromatic hydrocarbons (PAHs) in solution and the crystalline\nstate via allosteric regulation. Binding of one <b>Pc</b> gives\nrise to significant distortion and conformational changes in <b>1</b> that in turn lead to the inhibition of the second binding\nof <b>Pc</b>. The conformational changes associated with first\nbinding allowed an allosteric binding of a third component (PAHs)\nto form ternary complexes in solution. <sup>1</sup>H NMR titration\nrevealed moderately high thermodynamic stability for the ternary complexes\nin CDCl<sub>3</sub>. Competition between allosterically regulated\nternary complexes ([<b>Pc</b>·<b>1</b>·PAH])\nand 1:2 stoichiometric binary complexes of <b>1</b> with PAHs\n([PAH·<b>1</b>·PAH]) was elucidated. Further, the\nselective formation of ternary complexes in solution led to the generation\nof ternary cocrystals from a 1:1:1 mixture of three components in\nsolution. Our work shows that large π-conjugated nanographenes\ndesigned with allosteric recognition sites allow the construction\nof multilayer ternary complexes in solution and the solid state even\nwith dispersive π–π interactions.