Backbone‐Bridging Promotes Diversity in Heteroleptic Cages. Issue 12 (16th December 2020)

• Record Type: Journal Article
• Authors: Wu, Kai; Zhang, Bo; Drechsler, Christoph; Holstein, Julian J.; Clever, Guido H.
• Is Part Of: Angewandte Chemie international edition. Volume 60:Issue 12(2021)
• Page Start: 6403
• Page End: 6407
• Publication Date: 2020-12-16
• Subjects: coordination cages -- host–guest chemistry -- self-assembly -- solvent effects -- supramolecular chemistry; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.202012425
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: The combination of shape‐complementary bis‐monodentate ligands L A and L B with Pd II cations yields heteroleptic cages cis‐[Pd2 L A 2 L B 2 ] by self‐sorting. Herein, we report how such assemblies can be diversified by introduction of covalent backbone bridges between two L A units. Together with solvent and guest effects, the flexibility of these linkers can modulate nuclearity, topology, and number of cavities in a family of four structurally diverse assemblies. Ligand L A1, with flexible linker, reacts in CH3 CN with its L B counterpart to a tetranuclear dimer D1 . In DMSO, however, a trinuclear pseudo‐tetrahedron T1 is formed. The product of L A2, with rigid linker, looks similar to D1, but with a rotated ligand arrangement. In presence of an anionic guest, this dimer D2 transforms and a hexanuclear prismatic barrel P2 crystallizes. We demonstrate how controlling a ligand's coordination mode can trigger structural differentiation and increase complexity in metallo‐supramolecular assembly. Abstract : Rich structural variety in shape‐complementary metallo‐supramolecular assemblies is achieved by bridging ligands via their backbones. A series of unprecedented heteroleptic assemblies ranging from dimeric cages over a prismatic structure to a pseudo‐tetrahedron were obtained. The influence of linker flexibility, solvent and presence of guest molecules was studied.