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The self-assembly of molecular knots in water is challenging. Here, authors report the self-assembly of a trefoil knot in water via imine condensation, without relying on external templates; the handedness of the trefoil knot is determined by the chirality of the bisamino precursor.

We developed an improved, robust synthesis of a series of pillar[6]arenes with a varying number (0–3) of quinone moieties in the ring. This easy-to-control variation yielded a gradually less electron-rich cavity in going from zero to three quinone units, as shown from the strength of host–guest interactions with silver ions. Such macrocycle-Ag2 complexes themselves were shown to display an unprecedented, sharp distinction between terminal alkynes, which strongly bound to such complexes, and internal alkynes, internal alkenes and terminal alkenes, which do hardly bind.

Reported here is the synthesis of a macrocycle with equatorial coordination sites for the construction of self-assembled metallacages. The macrocycle is prepared via a post-modification on the equator of biphen[n]arene. Utilizing this macrocycle as a ligand, three prismatic cages and one octahedral cage were synthesized by regulating the geometric structures and coordination number of metal acceptors. The multi-cavity configuration of prismatic cage was revealed by single-crystal structure. We prove that a macrocycle with equatorial coordination sites can be an excellent building block for synthesizing structure-diverse metallacages. Our results provide a typical example and a general method for the design and synthesis of metallacages.

Homo radical spin-pairing interactions between two identical aromatic radicals are common in supramolecular chemistry, but hetero interactions between two different aromatic radicals are seldom observed. Here, the authors find that hetero radical pairing between a radical cation and a radical anion, together with Coulombic attraction, can drive host-guest recognition, representing a new supramolecular recognition motif.