A New Mechanically‐Interlocked [Pd2L4] Cage Motif by Dimerization of two Peptide‐based Lemniscates. Issue 50 (13th October 2020)

• Record Type: Journal Article
• Authors: Schulte, Thorben R.; Holstein, Julian J.; Schneider, Laura; Adam, Abdulselam; Haberhauer, Gebhard; Clever, Guido H.
• Is Part Of: Angewandte Chemie international edition. Volume 59:Issue 50(2020)
• Page Start: 22489
• Page End: 22493
• Publication Date: 2020-10-13
• Subjects: catenane -- chirality -- coordination cage -- mechanical bond -- supramolecular chemistry; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.202010995
• Languages: English
• ISSNs: 1433-7851

Abstract

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) π‐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. Abstract : A chiral macrocycle, equipped with two pyridine donors, assembles with Pd II cations to an unprecedented metallo‐supramolecular architecture by pairwise catenation of two figure‐eight‐shaped subunits. Interlocking in solid state and solution is driven by close non‐covalent interaction between the basket‐shaped macrocycles and coordinating ligand arms.