High-nuclearity Homoleptic and Heteroleptic Coordination Cages Based on Tetra-Capped Truncated Tetrahedral and Cuboctahedral Metal Frameworks

Abstract

Two new types of coordination cage have been prepared and structurally characterized: [M16(mu-L1)24]X32 are based on a tetra-capped truncated tetrahedral core and have a bridging ligand L1 along each of the 24 edges; [M12(mu-L1)12(mu3-L2)4]X24 are based on a cuboctahedral core which is supported by a combination of face-capping ligands L2 and edge-bridging ligands L1. The difference between the two illustrates how combinations of ligands with different coordination modes can generate coordination cages which are not available using one ligand type on its own.

Metallo-supramolecular capsules

“…Ward and co-workers have used approaches similar to some of those described for the formation of catenanes and molecular knots in the book chapter mentioned at the start of this section [11,[28][29][30][31][32][33][34][35][36]. The authors report on a series of ligands containing different numbers of N,N-bidentate chelating arms that are combined with various transition metals to form a library of metal-organic cage complexes that are based on different polyhedra.…”

“…In the broad topic of this section, transition metals are often used for templating, and significant advances in large superstructures or clusters have been made by Fujita and coworkers [12][13][14][15][16][17][18], Stang and co-workers [19,20], Raymond and co-workers [21][22][23][24][25][26][27] and Ward and co-workers [28][29][30][31][32][33][34][35][36]. Fujita has reacted pyridyl or pyrimidyl functionalised planar or near planar ligands (that are typically triangular) with cis-protected palladium in order to synthesise a substantial series of metalorganic cages [12][13][14][15][16][17][18].…”

“…Variation in the distance between the N,N-bidentate chelating arms by means of organic modification results in changes in cage complex formation, and the voids within these assemblies are filled with the appropriate anion depending on the metal salt employed [28][29][30][31][32][33][34][35][36]. Recently, the authors have reported the formation of two polyhedral cage complexes that are either homoleptic or heteroleptic with respect to ligand composition [36]. By employing a bis-bidentate ligand, with either zinc tetrafluoroborate or cadmium perchlorate, a capped truncated tetrahedral polyhedron is formed.…”

Tuning the coordination chemistry of cyclotriveratrylene ligand pairs through alkyl chain aggregation

“…[14][15][16] This phenomenon relies on a sliding scale of kinetic stability, whereby the dynamic nature of the coordination bond can be either exploited to enable ligand exchange, or relied upon for kinetic stability. 17 The tailoring of organic ligands and assembly conditions allows the chemist to exercise a degree of control over their self-assembly.…”

Lanthanide coordination polymers with pyridyl-N-oxide or carboxylate functionalised host ligands

“…[11][12][13] The study of sterically and interactionally similar ligand sets has garnered much interest due to their ability to selectively form homo-and heteroleptic complexes, allowing the formation of structures ordinarily inaccessible with a single ligand system. [14][15][16] This phenomenon relies on a sliding scale of kinetic stability, whereby the dynamic nature of the coordination bond can be either exploited to enable ligand exchange, or relied upon for kinetic stability. 17 The tailoring of organic ligands and assembly conditions allows the chemist to exercise a degree of control over their self-assembly.…”