The range of solvents across which a particular MOC is soluble tends to be quite limited. Cationic MOCs, for instance, are generally only soluble in high polarity solvents, such as acetonitrile and DMSO. The identity of counter-anions, however, can be used to dramatically alter solubility profiles; the highly lipophilic BAr F- (tetrakis[3,5bis(trifluoromethyl)phenyl]borate) anion was demonstrated to render Pd2L4-type MOCs soluble in apolar dichloromethane and chloroform, whilst sulfate anions were shown to make Fe(II) MOCs water-soluble. For MOCs based on carboxylate paddlewheel motifs, exchanging axial ligands can be used to similar effect; 4-tert-butylpyridine, 4-trifluoromethylpyridine and Lproline were shown to make a Rh24L24 cuboctahedron soluble in DMF, CH2Cl2/THF and water, respectively (Fig. ). Solubilising groups appended to ligand scaffolds are also commonly used to modify solubility. As the solvent of life, water-solubility is a commonly targeted property of MOCs, with various approaches investigated to achieve this. 40 Due to the relatively strong nature of metal-ligand bonds, in comparison to other non-covalent interactions, MOCs are often stable under a range of conditions, and can be designed to undergo post-synthetic modifications. That being said, paddle-wheel nodes are known to be hydrolytically unstable, and metal-ligand bonds are susceptible to competing nucleophiles. If well understood, these can be used to prepare stimuli-responsive architectures. Attempts have been made to enhance the stability of MOCs 45 through increasing the donor strength of the ligand, using more inert metal ions (e.g. Pt rather than Pd) and steric protection around the coordination sphere. In some instances, it is possible for metallocycles and cages to form mechanically interlocked assemblies. Often, interlocking is driven by interactions between assembly components, occluding any potential cavity space and limiting guest-binding potential. There have been reports, however, of metallo-catenanes forming from coordination cages, generating novel (compared to the monomeric assemblies) confined spaces accessible to guest species. The characterisation and study of MOCs in solution is most often carried out by NMR techniques, including diffusionorientated spectroscopy (DOSY). This is generally simpler for systems assembled from diamagnetic metal ions, such as Pd(II) and low-spin Fe(II), although useful information can often be obtained for paramagnetic systems too. Mass spectrometry (MS) is also ubiquitous, although often challenging, particularly for larger systems, due to instability of MOCs under MS conditions, although various "softer" techniques have been successfully employed. Characterisation of MOCs in the solidstate by SCXRD is often considered the gold-standard for unambiguous structure determination; however, structures that successfully pack to form X-ray diffraction quality crystals are not necessarily representative of what is predominantly in solution. Thus, when used to make conclusions about the structure of metal-organic assemblies, SCXRD data should always be used to support solution-phase data, rather than in lieu of it.