Hexnut[12]arene and its derivatives: Synthesis, host-guest properties, and application as nonporous adaptive crystals

Hexnut[12]arene (HN[12]) and its derivatives, a new class of sixfold macrocyclic arenes, were designed and synthesized in reasonable yield by a one-pot reaction at room temperature using dimethoxymethane as a methylene source. HN[12], which bears a large, symmetric, and rigid cavity, was easily functionalized at both the methylene bridges and the hydroquinone units. A water-soluble fluorescent HN[12] was synthesized and used as a host to encapsulate benzyl viologen dichloride in water with a high binding affinity of (3.4 ± 0.2) × 10 6 M −1 . The nonporous adaptive crystal (NAC) of HN[12] was found to capture not only inorganic molecules (iodine) but also trace amounts of large organic molecules (basic fuchsine) from water, which greatly expands the scope of NACs for adsorption.