A family of five [MIII2MII3]n+ trigonal bipyramidal cages (MIII = Fe, Cr and Al; MII = Co, Zn and Pd; n = 0 for 1–3 and n = 6 for 4–5) of formulae [Fe2Co3L6Cl6] (1), [Fe2Zn3L6Br6] (2), [Cr2Zn3L6Br6] (3), [Cr2Pd3L6(dppp)3](OTf)6 (4) and [Al2Pd3L6(dppp)3](OTf)6 (5) (where HL is 1-(4-pyridyl)butane-1,3-dione and dppp is 1,3-bis(diphenylphosphino)propane) are reported. Neutral cages 1–3 were synthesised using the tritopic [MIIIL3] metalloligand in combination with the salts CoIICl2 and ZnIIBr2, which both act as tetrahedral linkers. The assembly of the cis-protected [PdII(dppp)(OTf)2] with [MIIIL3] afforded the anionic cages 4–5 of general formula [MIII2PdII3](OTf)6. The metallic skeleton of all cages describes a trigonal bipyramid with the MIII ions occupying the two axial sites and the MII ions sitting in the three equatorial positions. Direct current (DC) magnetic susceptibility, magnetisation and heat capacity measurements on 1 reveal weak antiferromagnetic exchange between the FeIII and CoII ions. EPR spectroscopy demonstrates that the distortion imposed on the {MO6} coordination sphere of [MIIIL3] by complexation in the {MIII2MII3} supramolecules results in a small, but measurable, increase of the zero field splitting at MIII. Complete active space self-consistent field (CASSCF) calculations on the three unique CoII sites of 1 suggest DCo ≈ −14 cm−1 and E/D ≈ 0.1, consistent with the magnetothermal and spectroscopic data.

Supramolecular construction strategies have overwhelmingly relied on the principles of thermodynamic control. While this approach has yielded an incredibly diverse and striking collection of ensembles, there are downsides, most obviously the necessity to trade-off reversibility against structural integrity. Herein we describe an alternative “assembly-followed-by-fixing” approach that possesses the high-yielding, atom-efficient advantages of reversible self-assembly reactions, yet gives structures that possess a covalent-like level of kinetic robustness. We have chosen to exemplify these principles in the preparation of a series of M2L3 helicates and M4L6 tetrahedra. While the rigidity of various bis(bidentate) ligands causes the larger species to be energetically preferred, we are able to freeze the self-assembly process under “non-ambient” conditions, to selectivity give the disfavored M2L3 helicates. We also demonstrate “kinetic-stimuli” (redox and light)-induced switching between architectures, notably reconstituting the lower energy tetrahedra into highly distorted helicates.

Four [CrIII8MII6]n+ (MII = Cu, Co) coordination cubes of formulae [Cr8Co6L24Cl12] (1), [Cr8Co6L24(SCN)12] (2), [Cr8Cu6L24(H2O)12](SO4)6 (3), and [Cr8Cu6L24Cl12] (4) (where HL is 1-(4-pyridyl)butane-1,3-dione), were synthesised using the [CrIIIL3] metalloligand in combination with a variety of MII salts. The metallic skeleton of each cage describes a cube in which the [CrIIIL3] moieties occupy the eight vertices and the MII ions lie at the centre of the six faces. The axial coordination sites of the MII cations are occupied by either H2O molecules or Cl−/SCN− anions originating from the MII salt used in the synthesis, resulting in neutral 1, 2 and 4 and the cage in 3 being a 12+ cation; the charge-balancing SO42− anions accommodated both inside and outside the cube. Magnetic susceptibility and magnetisation measurements reveal weak exchange between nearest neighbour metal ions, mediated via the L− ligands. The modular assembly of the cubes suggests that any combination of [MIIIL3] metalloligand and MII salt will work, potentially resulting in an enormous family of supramolecular assemblies. The charge of the cubes is controlled by the nature of the ligand occupying the axial sites on the MII ions, suggesting trivial ligand exchange may offer control over, amongst others, solubility, reactivity, post-synthetic modification and substrate specificity. The large internal cavities of the cubes also suggest host–guest chemistry may be a fruiful route to encapsulating magnetic and/or redox active guests which could be employed to control magnetic behaviour, and the construction of multifunctional materials.

Cobalt(III) tetrahedral capsules have been prepared using an assembly-followed-by-oxidation protocol from a cobalt(II) precursor and a readily derivatizable pyridyl-triazole ligand system. Experiments designed to probe the constitutional dynamics show that these architectures are in a non-equilibrium state. A preliminary investigation into the host–guest chemistry of a water-soluble derivative shows it can bind and differentiate a range of different neutral organic molecules. The stability of this ensemble also permits the study of guest-binding at high salt concentrations.

The use of the novel pro-ligand H4L combining the complimentary phenolic oxime and diethanolamine moieties in one organic framework, results in the formation of the first example of a [MnIII12] truncated tetrahedron and an extremely rare example of a Mn cage conforming to an Archimedean solid.

We report that the acid–base induced changes to a cyclometallated platinum complex can be used to drive the exchange of accompanying ligands with different denticities.

The first molecular capsule based on an [Ir(ppy)2]+ unit (ppy = 2-phenylatopyridine) has been prepared. Following the development of a method to resolve rac-[(Ir(ppy)2Cl)2] into its enantiopure forms, homochiral Ir6L4 octahedra where obtained with the tritopic 1,3,5-tricyanobenzene. Solution studies and X-ray diffraction show that these capsules encapsulate four of the six associated counteranions and that these can be exchanged for other anionic guests. Initial photophysical studies have shown that an ensemble of weakly coordinating ligands can lead to luminescence not present in comparable mononuclear systems.

Mass spectrometry and drift tube ion mobility mass spectrometry have been used to analyse several isobaric, multicomponent cages yielding information on three dimensional structure, interactions and dynamics of assembly in the gas phase.

The exchange between different equilibrium and out-of-equilibrium platinum coordination modes can be orthogonally controlled thermodynamically with a proton input and kinetically using light.

A second generation palladium(II)-complexed molecular shuttle, featuring structural changes to the size and shape of the macrocycle, shows significantly increased rates of shuttling and improved co-conformational bias compared to the original system.

The discovery of interconvertible platinum coordination modes, which reveals and masks cis coordinating groups upon addition of acid and base, respectively, has been exploited to facilitate stimuli-responsive assembly and disassembly of both two- and three-dimensional metallosupramolecular architectures. Treatment of a binclear platinum complex with acid along with ditopic and tritopic donor ligands generated a molecular square and a trigonal prism, respectively, in good to high yield. These complexes were unambiguously identified using electrospray mass spectrometry, 1H NMR spectroscopy, and X-ray crystallography. Both assemblies can be disassembled into their constituent parts simply by treatment with base, and the prism can be cycled between the assembled and disassembled states by the alternate addition of acid and base.

The use of the novel pro-ligand H4L combining the complimentary phenolic oxime and diethanolamine moieties in one organic framework, results in the formation of the first example of a [MnIII12] truncated tetrahedron and an extremely rare example of a Mn cage conforming to an Archimedean solid.

A second generation palladium(II)-complexed molecular shuttle, featuring structural changes to the size and shape of the macrocycle, shows significantly increased rates of shuttling and improved co-conformational bias compared to the original system.

Cobalt(III) tetrahedral capsules have been prepared using an assembly-followed-by-oxidation protocol from a cobalt(II) precursor and a readily derivatizable pyridyl-triazole ligand system. Experiments designed to probe the constitutional dynamics show that these architectures are in a non-equilibrium state. A preliminary investigation into the host–guest chemistry of a water-soluble derivative shows it can bind and differentiate a range of different neutral organic molecules. The stability of this ensemble also permits the study of guest-binding at high salt concentrations.

The exchange between different equilibrium and out-of-equilibrium platinum coordination modes can be orthogonally controlled thermodynamically with a proton input and kinetically using light.

We report that the acid–base induced changes to a cyclometallated platinum complex can be used to drive the exchange of accompanying ligands with different denticities.

Mass spectrometry and drift tube ion mobility mass spectrometry have been used to analyse several isobaric, multicomponent cages yielding information on three dimensional structure, interactions and dynamics of assembly in the gas phase.

A family of five [MIII2MII3]n+ trigonal bipyramidal cages (MIII = Fe, Cr and Al; MII = Co, Zn and Pd; n = 0 for 1–3 and n = 6 for 4–5) of formulae [Fe2Co3L6Cl6] (1), [Fe2Zn3L6Br6] (2), [Cr2Zn3L6Br6] (3), [Cr2Pd3L6(dppp)3](OTf)6 (4) and [Al2Pd3L6(dppp)3](OTf)6 (5) (where HL is 1-(4-pyridyl)butane-1,3-dione and dppp is 1,3-bis(diphenylphosphino)propane) are reported. Neutral cages 1–3 were synthesised using the tritopic [MIIIL3] metalloligand in combination with the salts CoIICl2 and ZnIIBr2, which both act as tetrahedral linkers. The assembly of the cis-protected [PdII(dppp)(OTf)2] with [MIIIL3] afforded the anionic cages 4–5 of general formula [MIII2PdII3](OTf)6. The metallic skeleton of all cages describes a trigonal bipyramid with the MIII ions occupying the two axial sites and the MII ions sitting in the three equatorial positions. Direct current (DC) magnetic susceptibility, magnetisation and heat capacity measurements on 1 reveal weak antiferromagnetic exchange between the FeIII and CoII ions. EPR spectroscopy demonstrates that the distortion imposed on the {MO6} coordination sphere of [MIIIL3] by complexation in the {MIII2MII3} supramolecules results in a small, but measurable, increase of the zero field splitting at MIII. Complete active space self-consistent field (CASSCF) calculations on the three unique CoII sites of 1 suggest DCo ≈ −14 cm−1 and E/D ≈ 0.1, consistent with the magnetothermal and spectroscopic data.