A diaryl-linked [Pd₂L₄]⁴⁺ metallosupramolecular architecture: synthesis, structures and cisplatin binding studies

A diaryl-linked tripyridyl ligand (L), 2,6-bis[4-(3-pyridinyl)phenyl]-4-(hydroxymethyl)pyridine, was synthesised in good yield (57%) exploiting the Pd-catalysed Suzuki cross-coupling method and used to assemble a new [Pd₂L₄]⁴⁺ metallosupramolecular cage architecture. These systems have been characterised by NMR, IR and UV–vis spectroscopies, mass spectrometry, elemental analysis and by X-ray crystallography. It was shown using NMR spectroscopy and X-ray crystallography that the cage acts as a host for ${BF}_4^{-}$ anions. However, efforts to bind the anticancer drug cisplatin within the central cavity of the cage were unsuccessful. This appears to be connected to steric effects caused by the aryl spacer units of the ligands forming the cage.