Coordination polymers with embedded recognition sites: lessons from cyclotriveratrylene-type ligands

Coordination polymers with molecular recognition sites are assembled using cyclotriveratrylene ligands. Many show differential guest-spaces with host and lattice sites available, however common host–guest and self-inclusion motifs can block sites.

Supramolecular topology design of silver(i) and copper(ii) coordination polymers through a new semi-rigid sulfonyl ligand with different anion templates

A series of metal organic coordination polymers (MOCPs) of silver(i) and copper(ii) coordinated with a novel multifunctional semi-rigid sulfonyl ligand with different anion templates and oxidation states were designed for the first time. In addition, their atomically precise molecular structure was determined by single crystal X-ray diffraction analysis. In comparison, the topology of silver(i)-based MOCPs is affected significantly by different anion templates. The coordination modes are quite different with the anions varying: linear for ClO4-, trilateral for CO2CF3-, and tetrahedral for CO2C2F5-. Due to the difference of electron configurations between Ag(i) and Cu(ii), the coordinated configuration of the metal center is also different. While the coordinated configuration of Cu(ii) center tends to be placed in an octahedron. Furthermore, for the copper(ii) MOCPs, the oxidation state of the L ligand also plays an important role. When the N atoms in L were oxidized, the coordination mode of Cu(ii) became tetrahedral with Cu(ii) stuck on the bottom of the conventional octahedral mode. In general, it is an effective and controllable strategy to mediate the coordination mode and aggregation of supramolecular assembly-based MOCPs through the combination of a multifunctional organic ligand and its corresponding oxidation state design; elaborate metallic species and electron configuration selection; and suitable anion template introduction to generate multiform and hierarchical non-covalent bond interactions including π-π interactions and hydrogen bond formation that afford their coordination mode diversity.

2D networks of metallo-capsules and other coordination polymers from a hexapodal ligand

2D M₃L₂ coordination polymers (M = Re(i), Cu(ii), Co(ii), Ni(ii)) feature metal-linked M₆L₂-cages, and the Re(i) material absorbs iodine.

Copper coordination polymers from cavitand ligands: hierarchical spaces from cage and capsule motifs, and other topologies

Copper coordination polymers from cavitand ligands are reported including networked cage-motif structures, one of which takes up C₆₀ from solution.

The cyclotriveratrylene-type ligands (±)-tris(iso-nicotinoyl)cyclotriguaiacylene L1 (±)-tris(4-pyridylmethyl)cyclotriguaiacylene L2 and (±)-tris{4-(4-pyridyl)benzyl}cyclotriguaiacylene L3 all feature 4-pyridyl donor groups and all form coordination polymers with Cu^I and/or Cu^II cations that show a remarkable range of framework topologies and structures. Complex [Cu^I₄Cu^II_1.5(L1)₃(CN)₆]·CN·n(DMF) 1 features a novel 3,4-connected framework of cyano-linked hexagonal metallo-cages. In complexes [Cu₃(L2)₄(H₂O)₃]·6(OTf)·n(DMSO) 2 and [Cu₂(L3)₂Br₂(H₂O)(DMSO)]·2Br·n(DMSO) 3 capsule-like metallo-cryptophane motifs are formed which linked through their metal vertices into a hexagonal 2D network of (4³.12³)(4².12²) topology or a coordination chain. Complex [Cu₂(L1)₂(OTf)₂(NMP)₂(H₂O)₂]·2(OTf)·2NMP 4 has an interpenetrating 2D 3,4-connected framework of (4.6².8)(6².8)(4.6².8²) topology with tubular channels. Complex [Cu(L1)(NCMe)]·BF₄·2(CH₃CN)·H₂O 5 features a 2D network of 6³ topology while the Cu^II analogue [Cu₂(L1)₂(NMP)(H₂O)]·4BF₄·12NMP·1.5H₂O 6 has an interpenetrating (10,3)-b type structure and complex [Cu₂(L2)₂Br₃(DMSO)]·Br·n(DMSO) 7 has a 2D network of 4.8² topology. Strategies for formation of coordination polymers with hierarchical spaces emerge in this work and complex 2 is shown to absorb fullerene-C₆₀ through soaking the crystals in a toluene solution.

Controlling the assembly of cyclotriveratrylene-derived coordination cages

Ligand-functionalised cyclotriveratrylene derivatives self-assemble to afford coordination cages and topologically non-trivial constructs, including controlled assembly of M₃L₂ metallo-cryptophane and M₆L₈ cages.