Morphological Control of Heteroleptic cis‐ and trans‐Pd2L2L′2 Cages

• Published in: Angewandte Chemie International Edition Vol. 56; no. 28; pp. 8285 - 8289
• Main Authors: Bloch, Witold M., Holstein, Julian J., Hiller, Wolf, Clever, Guido H.
• Format: Journal Article
• Language: English
• Published: Hoboken John Wiley and Sons Inc 03.07.2017
• Subjects: cage compounds; Communication; Communications; morphological control; self-sorting; supramolecular chemistry; topology
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201702573

Control over the integrative self‐sorting of metallo‐supramolecular assemblies opens up possibilities for introducing increased complexity and function into a single self‐assembled architecture. Herein, the relationship between the geometry of three ligand components and morphology of three self‐sorted heteroleptic [Pd2L2L′2]4+ cages is examined. Pd‐mediated assembly of two bis‐monodentate pyridyl ligands with native bite angles of 75° and 120° affords a cis‐[Pd2L2L′2]4+ cage while the same reaction with two ligands with bite angles of 75° and 60° gives an unprecedented, self‐penetrating structural motif; a trans‐[Pd2(anti‐L)2L′2]4+ heteroleptic cage with a “doubly bridged figure eight” topology. Each heteroleptic assembly can be formed by cage‐to‐cage conversion of the homoleptic precursors and morphological control of [Pd2L2L′2] cages is achieved by selective ligand displacement transformations in a system of three ligands and at least six possible cage products. A doubly bridged figure eight: Integrative self‐sorting of geometrically distinct ligands and cages is regulated to form new [Pd2L2L′2] structures. For one example, X‐ray analysis reveals a doubly bridged figure‐eight topology, which is an unprecedented motif for metallo‐supramolecular structures. Furthermore, morphological control of a system of cages is achieved by highly selective ligand displacement transformations.