A New Mechanically-Interlocked [Pd₂ L₄ ] Cage Motif by Dimerization of two Peptide-based Lemniscates.

ABSTRACT: Most metallo-supramolecular assemblies of low nuclearity adopt simple topologies, with bridging ligands spanning neighboring metal centers in a direct fashion. Here we contribute a new structural motif to the family of host compounds with low metal count (two) that consists of a pair of doubly-interlocked, Figure-eight-shaped subunits, also termed "lemniscates". Each metal is chelated by two chiral bidentate ligands, composed of a peptidic macrocycle that resembles a natural product with two pyridyl-terminated arms. DFT calculation results suggest that dimerization of the mononuclear halves is driven by a combination of 1)?Coulomb interaction with a central anion, 2)??-stacking between intertwined ligand arms and 3)?dispersive interactions between the structure's compact inner core bedded into an outer shell composed of the cavitand-type macrocycles. The resulting cage-like architecture was characterized by NMR, MS and X-ray structure analyses. This new mechanically bonded system highlights the scope of structural variety accessible in metal-mediated self-assemblies composed of only a few constituents.

SUBMITTER: Schulte TR 

PROVIDER: S-EPMC7756597 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature