Metallo‐Supramolecular Self‐Assembly with Reduced‐Symmetry Ligands

Abstract

supramolecular self-assembly tends to be performed with single metal ions and single, highly symmetrical, ligands. This simplifies the self-assembly process as without sufficient bias within the system a mixture of products may be formed. However, with various applications of metallo-supramolecular species having been demonstrated, the ability to generate more intricate architectures is keenly sought after. The use of reduced symmetry ligands is one route to this goal, and allows access to lower-symmetry assemblies. Multiple coordination pockets can also be introduced in this manner, giving rise to assemblies with metal ions in different coordination environments, which can be exploited for the controlled synthesis of mixed-metal species. Herein we discuss the different approaches that have been used to control self-assembly with low symmetry ligands, including the use of mixed-denticity ligands, the incorporation of geometric constraints, charge separation strategies and the use of repulsive or attractive non-covalent interactions between ligands.[a] Dr.

Multi‐functional, Low Symmetry Pd2L4 Nanocage Libraries**

“…Exploiting coordination preferences to generate stable metallo‐ligands [8] has allowed mixed‐metal architectures [9] to be realised. Work in this group, [10] and by others, [11] has focused on an alternative, underexplored option: the use of low symmetry ligands [12] . Designed such that steric or geometric parameters, or a combination of the two, direct the self‐assembly process, exclusive formation of specific cage isomers from a potential mixture can be ensured.…”

Topological prediction of palladium coordination cages

“…This shortcoming is apparent in modern efforts to design heteroleptic cages that feature multiple functional groups to control the assembly outcome in a trial-and-error manner, especially when asymmetric linkers steric bulk or shape-complementarity are employed. [12][13][14] The latter strategy, employed by Clever and colleagues, is especially promising for the design of small M 2 L 4 cages with divergent functionalities. 12 A more robust model would provide a better basis of rational design for these new structures, and the application of shape-complementarity to larger designs, motivating the aim of our research.…”

Toward Molecular Cybernetics – the Art of Communicating Chemical Systems

“…A prerequisite for this highly selective self‐sorting scenario is the inability of sterically crowded phenanthrolines (phenAr 2 ) as implemented into 6–8 to furnish homoleptic intermolecular bisphenanthroline copper complexes [23] . Since homoleptic complexes of the type [Cu(phenAr 2 ) 2 ] + are sterically disfavored, [24] only heteroleptic copper(I) complexes with sterically undemanding ligands are feasible [25] …”