Synthesis of Carborane-Functionalized Macrocycles: Bond-Angle-Modulated Cavities and Cation-Mediated Assembly

Herein, a novel synthetic strategy for macrocycles based on a three-dimensional carborane skeleton via a cyclization reaction was developed. Further substrate scope experiments confirm that this strategy possesses excellent reaction compatibility. In addition, the cavity size of the macrocycle can be regulated by the bonding angle, in which the size of the macrocycle cavity formed by <i>para</i>-carborane (180°) is larger than that formed by <i>meta</i>-carborane (120°). More importantly, when a pyridine group is introduced into this type of macrocycle, nanotubes can be constructed through the coordination modes of [N···Ag⁺···N] and [N···I⁺···N]. The host-guest properties of the macrocycles are also explored to show the specific encapsulation of dichloromethane molecules through van der Waals forces. This work significantly enriches the structural diversity of supramolecular macrocycles and develops unique host-guest properties of the carborane-based macrocycles.