Over the past decade, the hexaphyrin skeleton has emerged as a multifaceted frame exhibiting strong interplay between topology, aromaticity, and metal coordination, opening new research areas beyond porphyrins. However, molecular recognition with hexaphyrins has been underexplored, mainly because of the lack of general synthetic strategies leading to sophisticated molecular hosts. Here we have developed a straightforward approach for capping the heteroannulene frame with tripodal units (e.g., tris(2aminoethyl)amine [tren]) through postsynthetic modification of a readily accessible meso-(2-aminophenyl) tris-substituted platform. The resulting tren-capped hexaphyrins, obtained in three steps from a 5-(aryl)dipyrromethane precursor, display remarkable features: (i) Considering the 28π-conjugated system, instantaneous and site-selective Zn(II) metalation at the level of a dipyrrin versus tren unit triggers a planar-to-singly twisted conformational change and hence a Huckel antiaromatic-to-Mobius aromatic transformation. In spite of the tripodal linkage, a smooth twist and efficient π overlap are preserved. (ii) Selective and cooperative binding of both an acetato ligand and an amino ligand to zinc occurs in distinct confined environments, reminiscent of substrate discrimination at the buried metal centers of metalloenzymes. The ligand binding pockets are allosterically tuned by monoprotonation of the tren unit. (iii) Substantial chiral induction of the molecular twist is achieved using chiral amino ligands (diastereomeric excess up to 77%, the highest reported to date for a Mobius compound), to which is associated a strong chiroptical signature in circular dichroism. These results provide unprecedented insights into molecular recognition with hexaphyrins, paving the way to innovative Mobius-type molecular hosts for sensing and catalysis.

An unprecedented mode of assembly of helical motives and Ag(I)  ions in the crystalline state is described. The combination of a Zn(II) helicate based on a 2,2'-bisdpm bearing peripheral benzonitrile moieties with AgX salts, leads to the formation of a tetranuclear core containing Ag-π interactions. Depending on the coordinating ability of the X(-) anion and the solvents used, the tetranuclear complex self-assembles into coordination polymers of varying dimensionality. From the sequence of coordination events (Ag-π or Ag-peripheral site), one may envisage two possible construction scenarios. However, the Ag-π as primary event seems reasonable owing to the rather weak binding propensity of the nitrile group and the chelating nature of the π-clefts.